Sciencemadness Discussion Board - Nitromethane, nitroethane, nitropropane synthesis via industrial route

Nitromethane, nitroethane, nitropropane synthesis via industrial route

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Melgar - 12-4-2010 at 10:40

Nitroparaffins like nitromethane, nitroethane, and the two isomers of nitropropane are produced industrially by reacting HNO3 and propane at about 150 psi and 400 degrees C. Now, these two reagents are far more easily obtained than the ones usually referred to for lab-scale syntheses, the only problem seems to be the specialized equipment needed. Still, this temperature and pressure combination is by no means beyond the capability of a homemade device built from stainless steel tubing. Has anyone looked into building something that could do this? If not, I'm thinking I could give it a try in the near future.

My plan for such a device consists of a propane torch tank, which would bubble propane through heated nitric acid. This pressurized mix of nitric acid and propane would then be fed into a heated coil of stainless steel tubing. At the end of the coil, there would be a manual valve, which would send the outflow through a condenser and into a collection flask.

Nitric acid/propane ratio would be controlled by changing the nitric acid temperature. Overall pressure would be controlled by warming or cooling the propane tank. Flow rate would be controlled by the manual valve. Everything after the nitric acid flask would be made out of 304L stainless steel, which is more or less impervious to concentrated nitric acid.

So, any chance of success here? What do I need to worry about? How exothermic is this exactly? I plan on using fairly narrow tubes, as they'd be able to withstand much higher pressures, plus in the event of some explosive-type reaction, there wouldn't be much in the tubes anyway.

Attached is a pdf detailing the industrial route.

Attachment: nitroalkanes.pdf (214kB)
This file has been downloaded 9864 times

[Edited on 4/12/10 by Melgar]

hissingnoise - 12-4-2010 at 11:43

To me, this reads like a recipe for disaster - you will not have the kind of neccessary control found in an industrial set-up and this could easily lead to a serious accident at some point.
Pick something safer, like sword-swallowing?

DJF90 - 12-4-2010 at 12:37

You do not cite a reference for the reaction, and as such this thread should have been opened in beginnings, as the moderators keep insisting. However, I would like to comment on what you have written.

Quote:

Nitroparaffins like nitromethane, nitroethane, and the two isomers of nitropropane are produced industrially by reacting HNO3 and propane at about 150 psi and 400 degrees C

I seem to recall the reaction being performed in the vapour phase at 450*C, with no mention of pressure (ref. IIRC is Functional groups - reactions and interconversions by Denis G Meakins, OUP).

Quote:

My plan for such a device consists of a propane torch tank, which would bubble propane through heated nitric acid....

Everything after the nitric acid flask would be made out of 304L stainless steel, which is more or less impervious to concentrated nitric acid.

For a start, I wouldn't use a propane tank to heat ANY acid. I'm fairly certain these are made of mild steel or the like; something concentrated nitric acid would probably make short work of at room temperature. Bear in mind that although 304L may be resistant to conc. nitric acid at room temp, nitric acid vapours at 400*C and 150psi are a completely different beast. Be sure before you do it, although I thoroughly advise you against it.

Melgar - 12-4-2010 at 14:59

Quote: Originally posted by DJF90

You do not cite a reference for the reaction, and as such this thread should have been opened in beginnings, as the moderators keep insisting. However, I would like to comment on what you have written.

Sorry, I have been reading about this reaction so much lately I forgot it isn't common knowledge. I edited my first post to include a reference.

Quote:

I seem to recall the reaction being performed in the vapour phase at 450*C, with no mention of pressure (ref. IIRC is Functional groups - reactions and interconversions by Denis G Meakins, OUP).

See the link I posted. And yeah, I'm well aware it's a vapor-phase reaction.

Quote:

I may not have been clear in my description. The propane tank would never be exposed to nitric acid, its job would merely be to pressurize the reactor with propane. I haven't had much luck finding high-temperature resistance charts for stainless steel and nitric acid. There does seem to be significant corrosion at high temperatures, although I'm not sure if that can be reduced by changing the concentration, or if that applies to liquid or vapor or both. Also, that corrosion is measured in mm/year, so I'm thinking a little corrosion might be acceptable. However, titanium would definitely work very well for this, it's just expensive.

I do have a degree in mechanical engineering, so I'm not totally clueless. As far as the reaction area, (ie, the heated part) I'm thinking molten zinc would keep it at the right temperature. If I did actually build this thing, I'd definitely build some sort of enclosure around it to contain any mechanical failures. Still, nitric acid vapor is preferable to liquid nitric acid as a reactant, since it's a lot less concentrated. The liquid HNO3 container would be in a protected spot off to the side, where any problems in the reactor area wouldn't affect it.

Z8320 - 12-4-2010 at 18:59

I'd like to suggest a safer route that doesn't seem to have been suggested before on this forum(or on any others I've seen.

1)Self Condensation of Nitromethane to methyl nitroacetate as depicted in the link below http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6...

2)Deprotonation with sodium methoxide of methyl nitroacetate and then nucleophilic attack of this on chloroacetate or bromoacetate which can be readily made from glycine by diazotization in the corresponding mineral acid. I suspect the rather exotic solvent used in this reaction can be replaced with any other solvent that won't be deprotonated by the sodium methoxide. I'm not even sure why it can't be done in methanol alone. The benzene also sounds unnecessary, seeing as it's only used in the extraction step. You could probably even figure out a way to improve on their relatively shitty yields.

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv6p0503

3)Decarboxylation of the resultant product is the only part I don't have references for, I just suspect it can be achieved relatively easily with the proper application of heat and base.

For the preparation of alpha halo carboxylic acids from amino acids:
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv8...

For the preparation of nitromethane from chloroacetate: http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1...

I suspect the above two links could also be used in conjunction to obtain a variety of nitroalkanes, though they too suffer in their yields a bit unless you use a bromocarboxylic acid; there's a patent for that, but I'm not going to dig it up unless anyone cares.

thereelstory1 - 12-4-2010 at 19:01

Melgar,

There is an easier synthesis using sodium nitrite, I believe. If you look in organic synthesis.org you will find it.

Z8320 - 12-4-2010 at 19:09

I realize this is a bit off topic from the relatively suicidal and difficult to achieve industrial reaction that probably won't have much better yields without some complicated gas recirculation, but there's little to suggest this will be easier than buying some simple reaction and distillation glassware and basic reagents.

I've tried any number of gas phase reactions using my tube furnace, and they're in general best avoided due to very low yields, explosion risk, consumption of time and money, and the inconvenience of controlling the pressure built up by the reaction. It's difficult to achieve stability even with PID controllers adjusting your temperature and pressure.

[Edited on 4/13/2010 by Z8320]

DJF90 - 13-4-2010 at 00:20

Z8320 - You won't decarboxylate 2-nitrosuccinate to nitroethane. Only the carboxylic group to which the nitro group is alpha can be removed readily.

thereelstory1: You obviously didn't read the first post.

Quote:

Nitroparaffins like nitromethane, nitroethane, and the two isomers of nitropropane are produced industrially by reacting HNO3 and propane at about 150 psi and 400 degrees C. Now, these two reagents are far more easily obtained than the ones usually referred to for lab-scale syntheses, the only problem seems to be the specialized equipment needed.

That would incorporate the use of nitrite don't you think?

gsd - 13-4-2010 at 08:08

Quote: Originally posted by Melgar

Nitroparaffins like nitromethane, nitroethane, and the two isomers of nitropropane are produced industrially by reacting HNO3 and propane at about 150 psi and 400 degrees C. ...............................

@Melghar

Check this paper. It talks about the reaction being conducted at atmospheric pressure.

gsd

P.S. If I am not mistaken, this topic is also covered in groggins.

gsd

Attachment: The Gas-phase Nitration of Alkanes.pdf (1.8MB)
This file has been downloaded 2223 times

Melgar - 13-4-2010 at 08:48

I'll post a quick sketch of the proposed reactor, since the design isn't exactly obvious. The whole thing would be behind thick plexiglass, in case there's some sort of nasty reaction, although the narrow tubing should prevent too much from reacting at a time. The pressure is controlled by changing the propane tank temperature. Initially, it would be best to have diluted HNO3, as that would slow down the reaction.

Also, I got offered a deal on .25 inch titanium tubing, and I went for it. So looks like l'm getting set to actually build this thing. And FYI, I am a mechanical engineer, so I really am qualified to design stuff like this. I would discourage anyone else from building a contraption like this too, however I have a piece of paper that says I know what I'm doing. :p

reactor.png - 66kB

Z8320 - 14-4-2010 at 15:17

Quote: Originally posted by DJF90

Z8320 - You won't decarboxylate 2-nitrosuccinate to nitroethane. Only the carboxylic group to which the nitro group is alpha can be removed readily.

I thought that might be the case, but I figured it wasn't too ridiculous considering that an amino acid can be decarboxylated. The easy solution here would be to use an alkyl halide instead of an alpha-halo acid. So pass dry HCl or HBr into boiling methanol, and you'll be set. Condense with dry ice if you're using HCl. This way you can alkylate and you don't have to worry about decarboxylating anything.

If you were both a chemical and a mechanical engineer, you might have a case about being qualified to build industrial chemical equipment. In lieu of that, this is an article with some words on titanium's resistance to nitric acid corrosion. http://www.azom.com/details.asp?ArticleID=1240.

I've attached a paper on the vapor phase nitration of saturated hydrocarbons. I suspect if you read this, you'll change your mind about certain aspects of your reaction, for instance, your temperature will not result in rearrangements to lower nitroalkanes; The only nitrated products you'll get will contain three carbons.

Attachment: Vapor Phase Nitration.pdf (591kB)
This file has been downloaded 1751 times

S.C. Wack - 14-4-2010 at 16:02

Sometimes hints are found in the original literature, and personally I'd consult that for Such A Project, but I'm a wet blanket with no sense of adventure.

Mr. H. must not have written any articles or patents worth reading, since this thread, and Ullmann's "detailing the industrial route" doesn't mention them.

Z8320 - 14-4-2010 at 16:55

Another thought I had was that you could take ethyl methyl ketone and form the corresponding alpha,alpha' dinitroketone with an alkyl nitrite or whatever other agent gives the same result; I'd be willing to bet a less dangerous and illicit alternative could be found. Then you could alpha halogenate and cleave the carbonyl with base in a manner analogous to the haloform reaction. You then decarboxylate the resulting alpha nitro propionic acid to nitroethane. If that works you could adapt it to any methyl ketone.

The main concern I have is whether or not alpha halogenation works in this situation; you might get halogenation on the higher alkyl side just like you do in the haloform reaction. Someone with MEK, access to alkyl nitrates, free time, and bleach should try this and see what can be isolated.

[Edited on 4/15/2010 by Z8320]

[Edited on 4/15/2010 by Z8320]

JohnWW - 14-4-2010 at 18:35

I'm a chemical engineer, among other things. With that sort of proposed pilot-plant scale process, I would be most concerned about the proper pressure-vessel design of the piping and reaction vessels, to safely withstand the vapor pressures of the reactants at the desired temperatures, and also to ensure that there are no leaks of hydrocarbon vapors that could result in an explosive mixture with air. The design would have to be in HNO3-resistant materials, e.g. Ti and vessels lined with glass, with extra thickness to be allowed for any likely loss of material from the inside surfaces due to corrosion. That reaction vessel, if at 420ºC, would have to be at a temperature which is safe for containing nitroalkanes without exploding due to autoxidation.

not_important - 14-4-2010 at 19:27

Quote: Originally posted by Z8320

... I suspect if you read this, you'll change your mind about certain aspects of your reaction, for instance, your temperature will not result in rearrangements to lower nitroalkanes; The only nitrated products you'll get will contain three carbons.

Actually, right near the start of the paper is the statement

Quote:

As a result the Commercial Solvents Corporation established an efficient industrial process for the production of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane by the reaction of nitric acid and propane at temperatures above 400' C.

and I've read elsewhere that nitration of propane in the range 420-450 C gives considerable amounts (10-25% each) of MeNO2 and EtNO2.

And Melgar, I'd not heat the tank of propane, as it's already under pressure. Instead place an inline heater between the propane tank and the HNO3 tank to heat the propane gas to the desired temperature. Use a valve on the propane tank to control flow, it'll be much more responsive than heating the tank.

Melgar - 15-4-2010 at 16:12

Quote: Originally posted by Z8320

If you were both a chemical and a mechanical engineer, you might have a case about being qualified to build industrial chemical equipment. In lieu of that, this is an article with some words on titanium's resistance to nitric acid corrosion. http://www.azom.com/details.asp?ArticleID=1240.

Yep, and the verdict is that titanium is a superb material for containing nitric acid at virtually all temperatures and pressures. In case you were warning me about the runaway reaction, I was aware of it. My plan was to dilute the nitric acid to like 90% or so, since that runaway reaction seems to only happen at concentrations of 98%+. Since titanium is expensive, I will probably use 304L stainless steel for the parts of the reactor at low temperatures.

Quote:

I've attached a paper on the vapor phase nitration of saturated hydrocarbons. I suspect if you read this, you'll change your mind about certain aspects of your reaction, for instance, your temperature will not result in rearrangements to lower nitroalkanes; The only nitrated products you'll get will contain three carbons.

Thank you, this was very helpful, as it gave a very good description of how changing different parameters effects output. Although the reaction does seem like it'd work at my initial values, after reading this, my plan is to lower the pressure to 50 psi or so, raise the temperature to the point where I'd use molten aluminum to regulate it, (melting point 660 C, and no, it doesn't dissolve titanium), and then use heavy-duty glass for the HNO3 and collection vessels. At 50 psi or less, I'd feel perfectly fine about using vessels rated at 80-100 psi. Plus, I already have a pressure gauge so I can closely monitor the pressure, and if I really wanted to make it safe I could install a burst-type valve rated at 75 psi or so, leading into a bucket of water. Also, I'm thinking I shouldn't have it loop around three times, since that'd complicate my design too much.

[Edited on 4/16/10 by Melgar]

Melgar - 15-4-2010 at 16:19

Quote: Originally posted by not_important

And Melgar, I'd not heat the tank of propane, as it's already under pressure. Instead place an inline heater between the propane tank and the HNO3 tank to heat the propane gas to the desired temperature. Use a valve on the propane tank to control flow, it'll be much more responsive than heating the tank.

If I had to get the pressure up to 150 psi, then I'd have to heat the propane tank in order to increase the vapor pressure to that level. See http://www.engineeringtoolbox.com/propane-vapor-pressure-d_1... . If I ran it at 50 psi instead, I suppose I could put the propane tank in ice water to ensure that it won't go above that pressure. Controlling it via the valve would be easier, but probably subject to more fluctuation unless I used a regulator. Still, this has actually all been good news since now I know I can run it at lower pressures and thus less inherent danger.

not_important - 16-4-2010 at 02:38

You really don't need pressure for small scale setups; I've seen vapour phase nitration of butanes run at 2 bar.

Rule 12 of the reference given earlier:

Quote:

Elevated pressures increase the reaction rate and the difficulty of temperature control without greatly increasing the yields; however, the effect of increased pressure is more important as the hydrocarbon series is ascended. In extreme pressures, nitration, presumably a second-order reaction, is so rapid that proper temperature control is very difficult

Rule 13 discusses the undesirable effect of catalysts and the possible need to pretreat the reactor lining.

Also not that contact times are critical and need good control, they generally run a fraction of a second and typically are followed by quick cooling. Maintaining a large excess of the hydrocarbon is useful for both good yields and reducing the possibility of runaway reaction; dilution with N2 helps there as well.

Melgar - 16-4-2010 at 07:08

Blah, accidentally reloaded this page and lost my nice long response.

I'm finding gas grill propane regulators online for cheap, some of which can regulate from 0 to 30 psi. I'm thinking I'll use one of these.

Also, you can dilute with several different neutral chemicals. I plan to dilute the HNO3 with water, in order to not have to make another inlet and make the HNO3 safer.

I'm a little concerned about the possible catalytic effect of titanium on the reaction. I've found a lot of papers describing titanium dioxide's photocatalytic oxidation ability, but none describing it as an oxidation catalyst in the absence of light. I may have to gold-plate the inside of the tube if it comes to that.

So now I'm thinking, single-pass reaction at low pressure in a titanium tube, with temperature regulated by molten aluminum. The titanium tube is, I believe, 70 cm long and 7mm in diameter. Fittings will probably all be stainless steel compression fittings.

Melgar - 19-4-2010 at 08:24

Damn, just had an idea. Would have been nice if I'd thought of it before I ordered all that crap. Anyway, alanine and beta-alanine are both available at health food stores, as free amino acids. How hard would it be to oxidize the NH2 to NO2, then decarboxylate the thing? Theoretically, alanine would give nitromethane and beta-alanine would give nitroethane. Could it work?

Eclectic - 19-4-2010 at 13:10

I've seen a method that bubbles the gaseous hydrocarbon through hot nitric acid, then into the bottom of a nitrate molten salt bath for reaction....Where is that damn patent....

http://pubs.acs.org/doi/abs/10.1021/i260018a011
http://v3.espacenet.com/publicationDetails/originalDocument?...

[Edited on 4-19-2010 by Eclectic]

sparkgap - 19-4-2010 at 15:55

Quote: Originally posted by Melgar

How hard would it be to oxidize the NH2 to NO2, then decarboxylate the thing? Theoretically, alanine would give nitromethane and beta-alanine would give nitroethane. Could it work?

Acetonitrile won't be too hard, but you'd probably have a hard time getting the hypofluorous acid at the health food store...

sparky (~_~)

not_important - 19-4-2010 at 21:07

You don't need HOF, you can easily make it by bubbling fluorine gas through aqueous acetonitrile.

Unfortunately, while there are several standard methods for oxidising amines to the corresponding nitro compounds, the referencee sparkgap gave seems to be the only one that gives decent yields if any non-zero yield at all..

Sedit - 19-4-2010 at 21:21

Quote: Originally posted by Melgar

Damn, just had an idea. Would have been nice if I'd thought of it before I ordered all that crap. Anyway, alanine and beta-alanine are both available at health food stores, as free amino acids. How hard would it be to oxidize the NH2 to NO2, then decarboxylate the thing? Theoretically, alanine would give nitromethane and beta-alanine would give nitroethane. Could it work?

You would more then likely be better off to perform the decarboxylation first using a high boiling point ketone as a catalyst and heat to yeild EtNH2 or MeNH2 followed by the oxidation of the amine with a mixture of oxone and acetone. There are references provided at The Vespiary for the process using the oxone.

Melgar - 19-4-2010 at 21:42

Quote: Originally posted by sparkgap

Quote: Originally posted by Melgar

How hard would it be to oxidize the NH2 to NO2, then decarboxylate the thing? Theoretically, alanine would give nitromethane and beta-alanine would give nitroethane. Could it work?

Acetonitrile won't be too hard, but you'd probably have a hard time getting the hypofluorous acid at the health food store...

sparky (~_~)

Yeah, I found that one too, then immediately ruled it out when I saw it involved gaseous fluoride. Still, I know I read once that you can just combine amino acids with sodium hydroxide to get the sodium salt, then just heat until they pyrolyze. Supposedly it doesn't give such good yields for more complicated amino acids like tyrosine, but for simpler ones like alanine or beta-alanine, yields are better. Anyway, I got some beta-alanine from the health food store, then mixed some in an aqueous solution of NaOH. Then I boiled all the liquid

Melgar - 20-4-2010 at 17:15

Yeah, it turns out oxidizing EtNH2 does not in fact give you nitroethane. It gets you acetaldehyde or acetic acid depending on how much oxidizer you add. Decarboxylating beta alanine or alanine is a decent way to get ethylamine though. And glycine should be able to be decarboxylated just as easily to form methylamine. Gee, an OTC way to easily make methylamine? I wonder who might possibly be interested in that?

I guess the plan for the propane/nitric acid reactor is still on then.

Sedit - 20-4-2010 at 17:40

Appearently my suggestion to you has fallen on deaf ears so once again repeat myself in hopes that you read it this time. Yes you can oxidise amines using a combination of acetone and oxone which forms the active species DMDO.

Do a search around for Tetrahedron Letters,Vol.27,No.21,pp 2335-2336,1986

A new synthesis of nitro compounds using dimethyldioxirane(DMDO)

Abstract:

Quote:

Dimethyldioxirane oxidizes primary amines to nitro compounds in a facile, mild, high yield process.

Here we report that aliphatic and aromatic primary amines are rapidly and efficiently oxidized to nitro compounds by dimethyldioxirane, DMDO. Indeed a survey of some general methods for the preparation of nitro compounds (2) suggests to us that the use of DMDO may be the method of choice. The conditions used are exceedingly mild and give the nitro compound as a solution in acetone. Table 1 summarizes our results with some representative amines.

Table 1. Oxidation of amines with Dimethyldioxirane(DMDO) (modified to fit)
Amine ==> Product = Yield (%)
n-Butylamine ==>1-Nitrobutane = 84%
sec-Butylamine ==> 2-Nitrobutane = 81%
tert-Butylamine ==> 2-Methyl-2-nitrobutane = 90%

I have the paper somewere but I ca not be bothered to look for a reference for someone that can not be bothered to read my post. You can see the yeilds are pretty good and the reagents are avalible.

The other suggestion that wizzed right on by was the use of a ketone to perform the decarboxylation. There are reports that use Carvone which can be isolated from some essential which it is by far the primary componate of. Look around and you will find some references for it.

[Edited on 21-4-2010 by Sedit]

Melgar - 20-4-2010 at 20:28

Quote: Originally posted by Sedit

Appearently my suggestion to you has fallen on deaf ears so once again repeat myself in hopes that you read it this time. Yes you can oxidise amines using a combination of acetone and oxone which forms the active species DMDO.

Do a search around for Tetrahedron Letters,Vol.27,No.21,pp 2335-2336,1986

A new synthesis of nitro compounds using dimethyldioxirane(DMDO)

Abstract:

Quote:

Gee, a reaction with a chemical that can be produced at yields of about 3% if I'm lucky... yeah, sorry if I seem to be ignoring all the pain-in-the-ass syntheses, but I want enough nitroalkanes to be able to use them for solvents and small engine fuels and such, and if I have to order $100 worth of chemicals for every 100 mL I can make, it's not worth it to me.

I do appreciate the help, but considering the title of the thread is about a SPECIFIC reaction, your response was off-topic.

Sedit - 20-4-2010 at 20:36

If one wants to get pissy about things the thread was started about someones death wish to aquire Nitroethane and you then brought up the topic of Ethylamine oxidation stating that it was impossible to do and I showed you otherwise.

Sorry if something is off topic from the direction you took it in but hey.... have fun with your rocket-engine...er... I mean nitroethane factory.

BTW: The persulfate + acetone production of DMDO yeilds about 3%... Maybe if one stops envisioning death traps they will see if there are other ways out there to make it. Considering that DMDO is only made that way because every lab has the materials on hand im SURE you can find higher yeilding DMDO synthesis.

[Edited on 21-4-2010 by Sedit]

not_important - 21-4-2010 at 03:09

Indeed, there are other related oxidation routes based on persulfate, peroxide, or ozoned O2/air.

or low cost I suspect that the hot tube reaction of ethanol and ammonia over a catalyst is cheaper than decarboxylating amino acids. You get a mixture of the mono, di, and tri amines, but using a largish excess of NH3 enhances the mono amine ration while the di and tri amines can be recycled back into the feed stream. There's at least on thread on this method around here.

That brings up one disadvantage of the alkane nitration route. You want short contact times, a few tenths of a second, which generally means fairly high gas flow rates. And you want high propane to nitric acid ratios to minimise by products and exothermic feedback. This means you'll have a lot of propane coming out of the back end of the condenser, propane that should be recycled back into the feed stream to boost yields based on alkane consumption; and this means pumping it back into the input.

Melgar - 21-4-2010 at 20:49

Quote: Originally posted by not_important

That brings up one disadvantage of the alkane nitration route. You want short contact times, a few tenths of a second, which generally means fairly high gas flow rates. And you want high propane to nitric acid ratios to minimise by products and exothermic feedback. This means you'll have a lot of propane coming out of the back end of the condenser, propane that should be recycled back into the feed stream to boost yields based on alkane consumption; and this means pumping it back into the input.

You don't have to dilute with propane. They do it in industry because it's really easy to just feed any unreacted propane back in through the front, but diluting with water or N2 works well too. Also, operating the reaction at lower pressures lowers the reaction speed, which requires a lower flow rate.

The oxygen in the air would increase the reaction rate, and also produce stuff like ethanol, propanol, acetaldehyde, acetic acid, formaldehyde, etc. At some point, I'd probably try adding oxygen to the system then see how feasible it is to separate out the different products. It may not be very feasible, in which case I'd stick to propane and nitric acid.

[Edited on 4/22/10 by Melgar]

Ephoton - 22-4-2010 at 20:36

you wouldnt catch me making a propane bomb thats for sure.

if I wanted nitro I would buy it or at a pinch I would use silver nitrite.

ketene was more than enough fun for this poor little bee.

I think you will find that you can make nitroethane from henry of nitromethane and formaldehyde.

dehydrate too nitroethylene then use a cat to reduce the double bond.

Melgar - 23-4-2010 at 06:04

Quote: Originally posted by Ephoton

you wouldnt catch me making a propane bomb thats for sure.

if I wanted nitro I would buy it or at a pinch I would use silver nitrite.

ketene was more than enough fun for this poor little bee.

I think you will find that you can make nitroethane from henry of nitromethane and formaldehyde.

dehydrate too nitroethylene then use a cat to reduce the double bond.

Interesting reaction. Distilling nitroethanol seems a bit dangerous, and I don't have any nitromethane (though I could probably get it if I tried). My latest proposal is actually pretty safe though. It only operates at 10-20 psi and uses only 1/4 inch tubing for the reactants, so there's not too much danger of explosive reactions. This wouldn't be a bomb, (ie, a closed, pressurized vessel) since it wouldn't be closed, so not as much danger. Anyway, I'll see if I can use it for other reactions too. The molten aluminum should do a good job of conducting heat around and preventing hot spots, plus, it'd absorb or release energy at its melting temperature, which is also a good temperature for this reaction.

Well, I just got the titanium tubing, so we'll see how hard this is to build.

Ephoton - 23-4-2010 at 06:14

good luck brother.
yes you need a special solvent to distill nitroethanol
to stop detanation from hotspots but the right solvent
and a vac and it can be distilled.

also I belive one can condense nitroethanol with an aldehyde

to recive the nitroalkene with an alcohol group on the terminal carbon of the propane chain.

this I belive though I am not sure can be dehydrated moving
the double bond in the secondary position to the terminal
position much like drones post on rhodium about dehydration

of cinnamic alcohol.

http://www.erowid.org/archive/rhodium/chemistry/cinnamyl.txt

REAGENT = Phosphoric acid
Ref = JACS 57; 1935; 151, 155

[Edited on 23-4-2010 by Ephoton]

Melgar - 24-4-2010 at 19:46

Thanks for the link! If this falls through, I'll definitely give it a shot. I haven't had time to build this thing yet, plus I want to contain the molten aluminum in an iron pipe, which means I have to run the titanium tube through the end caps, which means I have to drill holes in the end caps that are exactly straight, which means I need a drill press, which means I have to wait until the machine shop opens on monday. Also, I need to connect this titanium tube, which appears to be old USSR military stock, to 1/4 inch stainless steel tubing... not quite sure what that'll involve, but I'm sure I can figure something out...

Rosco Bodine - 25-4-2010 at 20:59

Quote: Originally posted by Melgar

I'll post a quick sketch of the proposed reactor, since the design isn't exactly obvious. The whole thing would be behind thick plexiglass, in case there's some sort of nasty reaction, although the narrow tubing should prevent too much from reacting at a time. The pressure is controlled by changing the propane tank temperature. Initially, it would be best to have diluted HNO3, as that would slow down the reaction.

Also, I got offered a deal on .25 inch titanium tubing, and I went for it. So looks like l'm getting set to actually build this thing. And FYI, I am a mechanical engineer, so I really am qualified to design stuff like this. I would discourage anyone else from building a contraption like this too, however I have a piece of paper that says I know what I'm doing. :p

You know this sort of apparatus could probably be made portable as part of an integrated system for synthesis ......
maybe even you could install everything in an RV. All of this seems strangely familiar somehow, like deja vu .....maybe it reminds me of a TV show or something , I just can't be sure. Possibly if I listen to some music it will come to me

http://www.youtube.com/watch?v=S9XEGBrA99E&fmt=18

Melgar - 25-4-2010 at 22:15

Quote: Originally posted by Rosco Bodine

Quote: Originally posted by Melgar

http://www.youtube.com/watch?v=S9XEGBrA99E&fmt=18

Cops? Breaking Bad? Not sure what show you're talking about exactly. Though, partial oxidation/nitration in a titanium tube is a pretty cool, versatile reaction. I mean, even just partial oxidation of propane should give me isopropyl alcohol, ethanol, methanol, propanol, and the corresponding aldehydes, ketones, and carboxylic acids. Separating them seems like it'd be a bitch though.

zed - 26-4-2010 at 03:52

Nitromethane is easy to make.

Nitroethane is somewhat more difficult.

Naturally, if you were using Nitropropenyl benzenes as starting materials, instead of hoping to produce them as end products, your quest would be easier.

C6H6-CH=C(NO2)CH3+C6H6-CH2-NH2+heat-->C6H6-CH=N-CH2-C6H6+CH3CH2NO2(Gas)

Shulgin suggests this approach for the isolation of Myristicin Aldehyde....A material hard to find in nature. As a byproduct, it seems to produce Nitroethane in very high yield. It distills off as it is formed, in the hot reaction mixture.

I suppose other Nitro-Alkenes might also be utilized. The important factor being the ability to form a high boiling shiff's base, that allows the Nitro-ethane to be distilled off in pure form.

http://www.erowid.org/library/books_online/pihkal/pihkal132....

[Edited on 26-4-2010 by zed]

Melgar - 26-4-2010 at 18:03

Aw, come on. I'm not just interested in making nitroethane for making illegal drugs you know. They're really useful chemicals, all of them. So anyway, what's a good way to coat an iron pipe so you can wrap a nichrome element around it without it shorting? I was going to use this fiberglass woven cloth stuff, since its melting point is well above that of aluminum.

zed - 26-4-2010 at 19:21

Legality is a regional issue. And, indeed Nitroethane is a useful reagent.

I'm just suggesting there may be more practical ways to produce it.

As Shulgin demonstrated, nitration of an alkene, produces a nitroalkene, which can be easily used to generate nitroethane.

Very handy for producing some benzaldehydes which may not occur in nature, and producing pure nitroethane, which is hard to acquire in some vicinities.

The am unaware of the full range of nitroalkenes that could be used to generate nitroethane. And, I am not aware of every method of producing such nitroalkenes. I'm simply offering that nitroalkenes might under some circumstances, become a reasonable sources of nitroethane.

As do others, I look forward to reading about the results of your experiments in vapor phase nitration.

Jimmymajesty - 29-4-2010 at 11:26

I have just run through the thread, unfortunately I have nothing vlauable to contribute, but, since I am working in the chemical industry too. I decided to post my thoughts, based on industrial and home experiments.

1 Pressure type reactions at home is suicide and does not worth the risk for a few percent of impure product.

2 Any type of metal with ccHNO3 expect tantalum is attacked by HNO3, this is the major reason the home made HNO3 distilling setups to fall apart during operation

And I never forget when I was told that "We could save costs If we made the whole nitrating unit of gold"

Apart with the joke, the whole setup should be made of glass.

I also do not understand why are you planning to control the temp with molten metals, It is absolutely impractical, I have a feeling that you have not even tried yet, after your first attempt you will also be of this opinion I guarantee!

Take a Pt100 element and calibrate it in the required region, and measure its resistance during operation, the voltage of your ohm meter does not cause temp increase during the measurement at all if you perform it within seconds.

I am eager to see your results anyway, so report back as soon as you finished, (hopefully not yourself

Melgar - 29-4-2010 at 20:19

Quote: Originally posted by Jimmymajesty

I have just run through the thread, unfortunately I have nothing vlauable to contribute, but, since I am working in the chemical industry too. I decided to post my thoughts, based on industrial and home experiments.

1 Pressure type reactions at home is suicide and does not worth the risk for a few percent of impure product.

2 Any type of metal with ccHNO3 expect tantalum is attacked by HNO3, this is the major reason the home made HNO3 distilling setups to fall apart during operation

And I never forget when I was told that "We could save costs If we made the whole nitrating unit of gold"

I've got the heating tube half-built, although I was running into problems electrically isolating the iron outer tube from the heating element. This time I'm going to try furnace cement. If that doesn't work, I may have to try some sort of enamel glaze. I'm also having trouble joining metric and SAE tubing. Anyway, to answer your questions:

1. 150 psi is not THAT high pressure, and wouldn't be that problematic as long as I purchased all components that were rated for this sort of use. Expensive, but possible. Anyway, the literature I was provided with states that there's no need to pressurize this reaction anyway, so I won't.

2. Glass is unreliable at the temperatures I want to use, at least for the reactor area. Also, just because nitric acid can attack virtually any metal, that doesn't mean it will under any conditions. Titanium, for instance, will not corrode even in the presence of aqua regia. It can corrode in the presence of nitric acid, but the nitric acid has to be really pure, and even then it's a rare occurrence. My nitric acid will be diluted to prevent this from happening, and also to moderate the reaction.

As far as controlling temperatures with molten metal, we'll see how well it works. The molten aluminum will be inside an iron pipe, so it shouldn't be that hard to deal with. One reason I wanted to use molten aluminum is because the reaction is exothermic and I wanted it to be able to deal with varying amounts of heat as I adjusted the reaction parameters. The other reason is because it conducts heat really well, and so would be nearly ideal for keeping the entire reaction tube at a constant temperature.

Anyhow, I can think of a bunch of ways to repurpose this equipment if the reaction doesn't work, so I don't feel as bad about the possibility of it not working so well.

Also, industry (at least in the developed world) is FAR more cautious than a home experimenter needs to be. For one, there's the whole liability thing. But the main reason is that in industry, they're dealing with tons of chemicals and if a reaction got out of control, well, it's easy to see how a disaster with a huge death toll could ensue. With my setup, even a catastrophic failure wouldn't be that dangerous provided I took the necessary precautions and did it outside.

Anyway, glad to have the feedback, since it makes me think critically about my own design.

not_important - 29-4-2010 at 21:03

I think that molten Al, at 660+ C, is too hot for this purpose; I believe that temperatures above 500 C cause more side reactions.

This process can be done in ferrous alloy by first coating the tube interior with fused alkali nitrates, so exotic alloys are not needed. The industrial guys aren't using tantalum.

The product yields are reasonable, especially considering the low cost of the reactants and that most of the products can be useful to the amateur.

Sedit - 29-4-2010 at 21:06

Quote:

With my setup, even a catastrophic failure wouldn't be that dangerous provided I took the necessary precautions and did it outside.

Watch the most recent episode of Mythbusters. They tryed to make a rocket out of a propane tank to get an idea of that a catastrophic failure of your system would look like.

There would be a huge need for wide open spaces because the resulting "explosion" is pretty large. You can expect a pretty large crater from any failer the system may have even if it wasn't a huge fireball like one would expect.

There is some very useful information to take away from there experiment though because if you watch when the tank ruptured the resulting shockwave extinqished the flame before it had a chance to ignite the propane cloud that formed. This would be the best case but I could not imagine how large the explosion would be if the propane was able to ignite. My guess it would be simular to a Fuel air exploasion judging from the footage that Mythbusters aired.

Jimmymajesty - 30-4-2010 at 00:10

You can insulate your kanthal wire with calcined Al2O3 elements, or go to the junkyard and dismantle an owen for that purpose.

I do not really worry about the glass being not able to handle high temps, as I went as high as 500°C in my acetaldehyde setup (see acetaldehyde thread) and there were no problems at all at this temp even after hours, when the controller switched on, the glass pipe was take up a dull red colour, and it was made of simple lab quality glass.. borosilicate maybe I dunno.

@ not important, the nitrating unit was designed to nitrate toluene to DNT, the nitrating pots were made of tantalum, IIRC not tantalum plated onto steel, but pure tantalum.

I think you could make usefull quantities of nitro parafins with a well designed setup. But with something that can be recycled e.g.: n-hexane. The advantage with propane that it can be bubbled into nitric acid and the HNO3 content of the gas+nitrating acid mix could be controlled by the temp of the acid.

I would use a glass tube as a reactor packed with Al2O3 granules.

Melgar - 30-4-2010 at 09:56

Quote: Originally posted by Sedit

Watch the most recent episode of Mythbusters. They tryed to make a rocket out of a propane tank to get an idea of that a catastrophic failure of your system would look like.

Do you see an oxygen tank anywhere in my design? No? Ok then. You're comparing apples and oranges. Without a source of oxygen, combustion is limited to the rate the fuel can mix with the air. Also, my propane tank has a regulator on it that limits the pressure to under 20 psi.

Quote: Originally posted by not_important

I think that molten Al, at 660+ C, is too hot for this purpose; I believe that temperatures above 500 C cause more side reactions.

This process can be done in ferrous alloy by first coating the tube interior with fused alkali nitrates, so exotic alloys are not needed. The industrial guys aren't using tantalum.

The product yields are reasonable, especially considering the low cost of the reactants and that most of the products can be useful to the amateur.

If I go too low though, I'm left with a lot of unreacted "reactants". I can alloy the aluminum with zinc to lower the melting point if needed though. And how are the tubes coated in fused alkali nitrates? Sodium and potassium nitrate both decompose below 400 C.

Jimmy - Two other advantages of propane: 1) You're a lot more limited in the products you end up with, making separation easier. 2) Propane is cheap. A barbecue-sized tank is about 4.5 gallons and costs around $20. Any other relatively pure hydrocarbon besides methane is going to cost the average person a lot more.

Anyway, the titanium tube is in place, so I plan to try that first. If it had been glass, I probably would have broken it by now. :-P

Sedit - 30-4-2010 at 13:04

Quote: Originally posted by Melgar

Quote: Originally posted by Sedit

Watch the most recent episode of Mythbusters. They tryed to make a rocket out of a propane tank to get an idea of that a catastrophic failure of your system would look like.

WTF are you talking about now? Im compairing apples to fucking apples so chill with the tude my freind...

I am making mention to what it would look like in the case that your PROPANE tank ruptured. It you even bothered to look up what I was talking about you would not be getting so damn mouthy. No source of oxygen? Hmmm let me breath for a second.... oh yeh there it is.

Now with your little kiddie attitude out of the way lets get down to the basic point I was making :mad:

In the event that your rig catches fire rupturing of the Propane tank, regulator or not, is a real possibility. Albeit most of the times these are provided with a fail safe mechanism to relieve the pressure in the event this tank catches on fire the most you will get its one hell of a flame thrower. BUT since im talking about worst case senerio and why this should be done far away from any dwellings what so ever, if it did go off full force the explosion is going to be VERY large.

I would love to see you pull this off and produce a very nice writeup of it because it would open the doors to many other vapor phase reactions as well. However I do see a large case of ones Ego getting in the way of there common sense so I guess we will just have to wait and see where this thread ends up at. Finished product or just alot of hot air.

[Edited on 30-4-2010 by Sedit]

Melgar - 30-4-2010 at 13:51

Ah... you mentioned a rocket so I assumed an oxygen tank was part of the equation... it would have to be in order to make a rocket. Which I guess could explain why their rocket didn't work. I'm trying to think how my system could fail like that though. After all, the tank would need to be heated really hot in order to rupture and a steel tank would dissipate heat pretty quickly if it was only being heated in one spot for instance. Even if somehow the nitric acid spilled all over it and ate through it, all that would happen is propane shooting out at 80 psi or so. Again, a flamethrower but no explosion. I suppose high explosives could also do that to a propane tank, but there won't be any in the vicinity. Unless you count nitromethane, but that's harder to detonate than NH4NO3. I suppose the risks would be similar to having a barbecue on a propane grill then...

497 - 30-4-2010 at 14:01

I'd just avoid the whole issue and place the tank a ways away from the apparatus..

I'll be interested to hear how it works, good luck.

Sedit - 30-4-2010 at 14:28

I agree with 497 theres no real reason to have the main tank anywhere near the system and it could be feed in remotely with no issues at all allowing for a much safer working for something like this. Even having it seperated by a wall would be of no concern and increase safety alot. My main concern was not so much the propane being the fuel for a fire that caused a rupture but the produced nitroalkanes could very well reach extremely high temperatures very quickly in the event that things went very wrong.

On the show they where trying to bust a myth that a propane tank in a garage that caught fire acted like a rocket and shot into the air. They where unable to replicate this myth for reasons just like you stated there is no oxygen. They even thinned the bottom of the tank and placed it directly on top of the burner and once again all they got was a tank rupture and a huge cloud of LP which DID NOT ignite. The force of the explosion blew out the ignition source so the LP just hung there in a cloud. I couldnt imagine the result if this was able to find ignition. Non the lest I could imagine that the shockwave from the tank rupture along could very well break some windows from a good distance.

Melgar - 30-4-2010 at 16:59

Oh, well right, obviously. I had that in my first diagram. The whole thing would be about six feet long, and the collection flask would be completely on the other side of the apparatus. And it'd only be a liter or so in capacity. I was going to get one of those little portable tanks of propane, but now I'm planning for the barbecue grill 20-pound variety because they make regulators for them. Plus the reactor would have such a small volume that even an explosion wouldn't be enough to rupture the tubing. After all, a gas exploding doesn't have anywhere near the increase in volume as a solid or liquid exploding. I suppose there's always a chance methyl nitrate or something similar could form, but it seems like it'd immediately decompose on its own.

Sedit - 30-4-2010 at 17:30

Six feet does not really sound like it would be enough honestly. From a legistics point of view why not have every part seperated from the other by as much space as possible. When you think in terms of fire 6 feet is not really that far considering adding a longer hose for the propane feed would be a simple addition and keep the fire risk way down.

What diameter of tubing ID and OD are we talking here for the main part of the reaction to take place? Have you calculated the pressures it can take and what it will be, and possibly could be subjected to under backfire conditions?

Given that folks have managed to make Ketene without killing or poisoning themselfs this seems more then feesible but I would keep the propane take on a long, atlest 10 feet or more feed(I'd go more). I would just love to see something like this in the workings instead of reading about its pieces in the paper.

PS: You may still want to look into the Ethylamine oxidation using oxone or simular methods just for the hell of it. There are methods out there that produce 80% solutions of DMDO which would be more then enough to produce a decent amount per run making the synthesis of EtNH2 the main money pit. Just something to consider.

S.C. Wack - 9-5-2010 at 03:22

Please continue to refuse to read Mr. H's worthless articles, and the many accessible garbage patents by him (and other retards later) which would be found by entering the original patent numbers at google patents.

I understand, since all of my art study was done with coloring books.

And shame on me for not having or getting an FTP program to upload this to scipics directory, but clearly this crap is of limited interest.

http://ifile.it/u2w59py

leu - 9-5-2010 at 08:20

Those articles by Hass et al provide a lot of useful information on how this procedure has been done, the practice for many decades has been to mix the nitric acid into the alkane using an aerosol spray mechanism

Molten salt baths have been used to heat the reactor in laboratory practice :cool:

Melgar - 11-5-2010 at 13:52

I set up a small benchtop-size reactor today, since I was tired of waiting for packages. It bubbled propane through nitric acid in a test tube, then sent it through a glass tube with a nichrome coil wound tightly around it. Then it was bubbled into a flask. Initially, the flask had water in it, but then I used methanol, since I'm sure nitroalkanes would be a lot more soluble in that. Also, methanol has a lower boiling point so it cools the reactants more and is also easier to separate via distillation. I don't have any sort of spectrometer so I had to go almost entirely on smell. Initially, I smelled mostly acetaldehyde and formaldehyde, but after tweaking the propane pressure and the current through the coil (via a light bulb dimmer switch) the smell eventually became one I was not familiar with. Once the nitric acid is used up, I'll distill it and see what I've got.

Temperature was measured at around 350 C, but that's the outside of the tube, and just with an infrared thermometer. The coil was glowing in spots so that couldn't be all that accurate though. Occasionally, when I changed the gas pressure or the current, a drop of nitric acid would get sucked into the tube and there would be a pop and a little burst of flame. Not something that looked dangerous though.

Anyway, this will be a nice way to understand the reaction before building a bigger setup.

Vogelzang - 11-5-2010 at 14:33

I found these patents in 568/927 & 568/943

US 2780657 Process for preparing aromatic nitro compounds
nitrobenzene from benzoic acid

US 3014972 Process for the preparation of organic nitro compounds
RX + MNO2 -> RNO2 in DMSO or DMF

US 3054827
cinnamate -> nitrostyrene 25% yield col 4 table II

US 3328466 Photochromic cis-1-aryl-2-nitroalkenes
IR band 10.34 microns (trans) ex 1

US 4469904 Preparation of nitro compounds by vapor phase nitration of carboxylic acids
acetic acid -> nitromethane

US 4808747 Process for producing alkylidene compounds and arylidene compounds

US 4820881
col 1 line 37+
U.S. Pat. No. 4,210,609 and Japanese No. 45-14048 teach a method of removing
colorants from nitro paraffins by passing the nitro compound through a bed of
activated alumina ('609) or distilling the nitro compound over a bed of
activated alumina, aluminum fluoride or sodium silicofluoride. These processes
have been known to exhibit spontaneous decomposition of the substrate causing
catastrophic results.

US 7265251 Process for the preparation of nitroalkenes
Styrene + I2 + nitrite, also HI from alkyl nitrite and I2

US 3192271 Method for conversion of 1, 2-dinitro-paraffins to 1-nitroolefins
pseudronitrosite -> nitroalkene?

US 3379710 Process of preparing a nitro-nitroso dimer from an olefinic hydrocarbon and a mixture of NO and NO2

US 4066699 Process for the hydrogenation of nitrated paraffins using a palladium on carbon catalyst characterized by a low ash and a low halide content

[Edited on 11-5-2010 by Vogelzang]

zed - 14-5-2010 at 14:56

Vogelzang,

Thank you for the references! Vapor phase nitration of carboxylic acids looks interesting!

peach - 16-5-2010 at 06:25

I don't know if this idea has already been ditched for another or this suggestion made, but how about lining the insides with a layer of silver?

They used to do that at the plants where they were making nerve agents after the second world war and during the cold war, given the stuffs propensity to dissolve through the pipe work and then blast the staff in the face. Mmm, steaming hot sarin... that's going in the accident book alright!

The minute you start dealing with temperature or pressure you're in trouble, combine the two together and add strong reacts and damn... I'll pass; unless I'm getting mondo cash for the privilege.

That looks like a Bunsen burning doing the cooling. A hose?

Google for "hcl generators report" and click the second link, the pdf 'Hydrogen Chloride Gas Generators Associated with Clandestine Drug Labs'

That's some interesting reading on combining heat, pressure and corrosive materials together.

It's also pleasing to see that even when they tried to ruin one they couldn't drive the pressure up very high at all. The corrosion on the inside of the cylinders probably retards the rate of failure to some extent.

But this is still not as bad as 400C, 150psi and nitric acid.

If you're going to try this, DO NOT try it anywhere near a house or anyone else; that's just ridiculously irresponsible. I'd also cover is with something to reflect any kind of burst escapee.

[Edited on 16-5-2010 by peach]

Melgar - 18-5-2010 at 05:57

Actually, I'd toned the design down to not be pressurized. As it turns out, the only reason for the pressure was so it was easier to separate unreacted propane.

I don't suppose it'd be possible to do some sort of kolbe electrolysis with a propionate salt and sodium nitrite? Presumably with an excess of propionate, since it's cheap and would boil away as butane.

I set up another setup, and am getting a strong nitroalkane smell, but only like 1 mL per hour. It uses reactants at a really low rate though. Of course, this is with 5mm OD glass tubing, so maybe I need to up the tubing size?

not_important - 18-5-2010 at 07:14

Probably better to come up with a design using multiple tubes in parallel. If you scale it up you need a good heat exchange to get fast temperature ramping. Relatively short contact times are desirable, and large diameter tubes will make it difficult to get quick uniform heating without strong mixing and high space velocities. This even more so with glass as it is not a real good conductor of heat.

I note that some versions of this process keep the alkane and HNO3 separate until they are at or near the reaction temperature, the HNO3 being carried in a stream of N2 instead of alkane. Both gas streams go through a preheater, then into the reaction chamber where they are mixed, and afterward exiting the heated reaction chamber a spray of cold water is used to quench the gases.

Melgar - 18-5-2010 at 13:02

peach - oh, silver has a really strong reaction with nitric acid, btw. That's why I was hoping titanium would work. Though, now I'm not sure if it would catalyze oxidation reactions or not. The one paper says that heavy metal oxides catalyze oxidation, but I'm pretty sure titanium isn't in that category.

not_important - I guess multiple parallel tubes could be another way to go. I found that the reaction takes place mostly in the first five inches of the tube (that's what she said!) and so making it longer would seem to be counterproductive.

not_important - 18-5-2010 at 20:53

Longer tubes would require higher gas flow rates then. You also may need better condensing, you may be losing product in the exit gases.

You're seeing a disadvantage of gas phase methods, the volumes needed - 22.4 liters/mole at STP as a rough number. Your ml of product would have occupied 300 cc as a gas. That's the other reason for higher pressures, run at 10 bar and you have 10 times the concentration of reactants and products.

Ephoton - 18-5-2010 at 21:42

id try one of these if I was to try something like this.

http://cgi.ebay.com.au/Quartz-Tube-25mm-OD-x-1000mm-1-D-x-40...

not_important - 18-5-2010 at 22:35

Even 25 mm diameter might be too large, unless you inserted something to insure the gases swirled so as to be uniformly heated by the wall. You also need a fairly fast gas flow, as it looks as optimal contact times is no more than 1 second. That suggests a gas flow rate on the order of 100 ml/sec for such a tube.

Melgar - 18-5-2010 at 22:39

Quote: Originally posted by Ephoton

id try one of these if I was to try something like this.

http://cgi.ebay.com.au/Quartz-Tube-25mm-OD-x-1000mm-1-D-x-40...

I have a couple of burnt-out HPS bulbs, I wonder how hard it'd be to scavenge the alumina arc tubes out of those things? Heck, I could probably go down to my local hydroponics shop and get some bigger ones easily enough. The biggest one I have now is probably 1/4 inch ID and 6 inches long.

As far as flow rates, my propane source is still one of the little hand torch tanks. I haven't moved up to a barbecue grill tank yet, although I plan to once I have a better idea of what my design needs to be capable of.

Panache - 25-5-2010 at 03:33

if i may make a suggestion, it would appear that the challenges involved are not with the chemistry rather with the engineering and as such it seems reasonable that once you have your system setup you run it with water in place of nitric acid and compressed air in place of propane. you can safely run it for several hours giving you ample time to assess flow rates, contact times, condensing efficiency etc, detect leaks, and get accurate internal temperatures, ir thermometers are hopeless with glass/quartz, you need to get a thermocouple in there during the non corrosive run as a minimum to garner a ballpark. Vapour phase is very sensitive to all the things NI has referred to and temperature is not something you want to run blind on.
Additionally do not rely on the out-coming gases throughput into a liquid to condense, you will setup all sorts of ununderstandable (thats a word i just made up) and varying pressure gradients through your system. An alternative decent condenser system if you are just trying to ascertain basics without setting up properly would be to place a large cooling chamber made of anything you have handy that can survive the conditions that your exit flow runs into just to take the brunt off the exhaust then grab a block of the coldest ice you can find and lengthwise drill holes in it, this will go at the outlet of your cooling chamber, sit the outlet pipe from the cooling chamber several inches into the block. If possible the cooling chamber should have the entry gases coming in at the top and exiting at the bottom, if you can get a round one set it up to generate a swirling path to maximize the pathlength. Thawing ice is an excellent surface for condensing. perhaps i should have made some paragraphs, apologies.

franklyn - 25-5-2010 at 05:58

Angus Chemicals , a subsidiary of Dow Chemical Co. since June of 2000 is the only
domestic manufacturer of Nitromethane. Angus makes just one grade of 98.4% pure
Nitromethane in a plant in Sterlington Louisiana for industrial use , car racing , and a
small amount devoted to RC model use. Prospective resellers and manufacturers are
subject to review and are eligible to receive bulk shipments only if approved by Angus.
The Angus plant produces Nitroalkanes on an industrial scale by vapor phase nitration
of Propane under pressure at up to 475 ºC. The resulting mixture of nitroparaffins ,
unreacted feed stock , and waste by products ( water, hydrogen , nitric oxide and
carbon monoxide and dioxide ) are then separated by filtration , distillation , and
other chemical processes into individual product lines and by products. Accordingly
composition of the production yields 25 % Nitromethane , 10 % Nitroethane ,
40 % 2-Nitropropane , and 15 % Nitropropane. Commercial Nitromethane thereby
contains residual amounts of Nitroethane and Nitropropane isomers as impurities.
The product also has trace amounts of Formaldehyde , Acetaldehyde , Methanol and
Ethanol. Nitromethane itself is affected by photodecomposition , and breaks down
slowly on exposure to light. Nitromethane is chemically stable when kept in the dark
at room temperature sealed in brown bottles or cans. Some Nitromethane fuel is tinged
yellow because it has an indicator dye in it. VP Racing Fuel brand Nitromethane has
this yellow dye. The purpose of it is to alert you if it has been accidentally sensitized.
Sensitized nitro does not burn , it explodes. If it turns blue or green it is sensitized.
Chinese bulk manufacture of Nitromethane relies on the method of synthesis used for
obtaining reagent grade product directly from precursors Dimethylsulfate and NaNO2
in a water slurry. It is obtained in 57 % yield when 1 mol of Dimethylsulfate is added
to 1 mol NaNO2 in a saturated water solution and mixed cold until the first stage is
completed when a second mol of of Nitrite is added. The reaction is carried at or below
20 ºC to limit formation of coproducts , primarily methyl nitrite and an aqueous solution
of Na2SO4. The mixture is then distilled at reduced pressure. Nitromethane is initially
obtained over 96 % pure , the primary contaminant being water. This and other residual
by products are removed in a two stage batch distillation. The resulting product is then
greater than 99 % having less than 0.1 % water.
These processes are outlined in Vogels Practical Organic Chemistry 3rd Editon on
pages 302 & 303. The lower yield preparative method using Chloracetic acid and NaNO2
is given on page 307. The purest Nitromethane is obtained as the sole product of
the reaction of Methyl Iodide on Silver Nitrite.

.

Melgar - 26-5-2010 at 02:25

Panache - thanks for the tip. It makes sense that there would be pressure fluctuations as the bubbles moved out the tube, and in fact I noticed some effects of pressure fluctuations due to the propane bubbling through nitric acid.

I had to move out of where I lived last week before I could do any more of this experiment, but I'll start again once I get a new place. In the meantime, more theory! Nitroethane seems to be the most popular product among the nitroalkanes, probably because it can't be purchased, so it'd be nice if it could be produced as the major product instead of a minor product. However, I've read a lot indicating that if ethane is used instead of propane, nitroethane is something like 85% of the yield. I'm wondering if it's worth it to set up an electrolysis cell with glacial acetic acid. Supposedly, the gas bubbles coming from the cathode are one part ethane for every two parts CO2. Electrolysis can be kind of slow, so I was thinking really big electrodes to increase surface area. I don't think CO2 interferes with this reaction, so this could work, not to mention the fact that the vast majority of the GAA ends up turning into a gas. Of course, GAA could interfere in the reaction a little, so the electrolytic cell should be kept cold too.

Panache - 26-5-2010 at 12:13

Ethane can be easily and safely purchased from any decent refrigeration supplier, it is expensive though, around $150/kg because of its high purity, it is used in ultra low freezers in the second stage compressor.
Or you could move to where i live in Australia, our town gas is 5% ethane, 95% methane, easily separable, however the methane would need to be burnt/vented, not very good for our warming planet. Perhaps you could plant some trees to offset it.

Ephoton - 31-5-2010 at 03:04

maby if some one can get a hold of this paper it may help

http://pubs.acs.org/doi/abs/10.1021/ie50407a004

Recent Developments in Nitroparaffins
H. B. Hass
Ind. Eng. Chem., 1943, 35 (11), pp 1146–1152
DOI: 10.1021/ie50407a004
Publication Date: November 1943

Ephoton - 31-5-2010 at 07:46

sorry S. C wack im a dumb ass

nice find there still you were hinting at it when the thread first started

.

ill make sure I read more of your posts you must think me a total prat.

Jimmymajesty - 3-6-2010 at 10:59

I've been thinking about the idea ever since I busted the myth of so called "one pot TNT snyth" but never had the balls to try it out, as the MSDS of the hexane says, that Nitrogen oxides are form explosive mixtures with it.

When you pour together hexane and nitric acid which contains water, and boil it, the condensate will be consisting of HNO3+H2O+Hexane of given proportions. This gas mixture would be fail proof, that is the hexane will be in large excess no matter what you do. So the reaction would not end up in a Kaboom.

Any ideas to make this method failproof? I am still do not feel this reaction safe enough to try it out

497 - 17-6-2010 at 22:52

This patent might be interesting to some here. It is a patent that gives the conditions to produce a mixture of 83% nitroethane and 17% nitromethane by vapor phase nitration of propyl nitrite with 50% HNO3 vapor at 400*C (or NO2 at 300*C), at atmospheric pressure. Interestingly, they use an aluminum tube immersed in a molten salt as the reactor. It is advantageous because it results in a simpler mixture of products that should be much easier to purify... Assuming you can get n-propyl alcohol, propyl nitrite is ultra easy to synthesize.. The extra carbon is lost as formaldehyde. If you wanted nice pure nitromethane, you could use isopropyl nitrite instead, which results in only nitromethane (and acetaldehyde byproduct).

[Edited on 18-6-2010 by 497]

Jimmymajesty - 26-6-2010 at 15:00

I also read a patent in which an olefin, preferably propylene was used to produce nitromethane, the olefin carbon backbone is oxidized and the methyl group is cleaved to afford nitromethane.

I tried to reproduce the patent but the whole setup exploded to the stratosphere. IIRC they failed to mention that the propylene is react even with COLD! nitric acid (or rather it is evident for everyone just I am the fucktard..), so when I jerry rigged the setup and started it, a lot of nitric acid droplets made into the hot tube because of the exoterm and frothing, which are initially caused loud cracking noise then made small explosions then detonated the whole tube.

I also tried out the nitration of higher paraffins, I used lighter filler gas (30%propane 70% butane). The setup was made of a bubbler and a quartz tube with kanthal wire connected in serial. by adjusting the heat of the tube and the flow rate of the combustible, three different stage could be attained (the bubbler was @ room temp).

1, it was like, when you drop ethanol to cc HNO3 + H2SO4 mixture.
2, a LOT of formaldehyde.. not acetaldehyde.. I am very familiar with its smell.
3, Something that I cannot smelled before, so I cannot really describe it properly.. carrot comes to mind.

I have all the necessary glassware to make it on large scale.. and I definitely will sometime.. maybe I should wait till new years eve

[Edited on 26-6-2010 by Jimmymajesty]

Jimmymajesty - 2-7-2010 at 11:45

I repeated the experiment again on small scale today, to find it out how can you make the reaction to explode.

Here is what CANNOT be followed: I slowly bubbled butane into the nitric acid, and started to heat it, when the nitric acid was about to reach its boiling point, and NOx fumes are started to appear above the acid, I turned up the butane flow, in almost each case, a peculiar sound could be heard before the explosion, it was like when you blow a whistle.
I do not know if it could be noticed even on large scale, in this experiment the glass tube inner diameter was only 1mm.

I am going to try it out in the fortcoming 2-3 weeks and post the results, I hope not only formaldehyde that can be obtained this way, since I almost choked at every trial, in spie of that it was done outside.

Jimmymajesty - 3-7-2010 at 04:28

One of the pdf that S.C. Whack uploaded mentioned that during their experiements, an explosion occured when fuming nitric acid was used!

I thought that the dissolved NOx will be readily swept out by means of the hydrocarbon feed, so my plan was to use ~98w% red nitric, and bubble lighter filler gas through it, without heating the bubbler, until the nitric becomes colourless.

I poured ~250ml >98% HNO3 into a 1l bubbler, and started to feed hydrocarbon into it, after about 30min the nitric became hot to the touch (damn) and a lot of brown fumes come out of it, after one hour the bubbler was stilll hot. Unfortunately the dissolved NOx cannot be swept out so easily as I thought, so it cannot be used as it is.

The dissolved NOx oxidize the butane and heat the nitric as a result of that, more NOx forms which oxidizes more butane, so one will definitely ends up in hospital if use fuming nitric to GP nitration, hope I saved some life with this post, mine included

Based on my small scale experiments, I found that the vapour pressure of the cc nitric is high enough to make a HNO3 hydrocarbon mix by simply bubble the gas through the acid, and also the bursting bubbles that come up to the surface will volatilize more nitric which ensures more HNO3 in the vapour phase by which I managed to react the CH.
Now cc HNO3 cannot be used, and diluted HNO3 is sucks too because of the aforementioned. I will try to decolorize the nitric with a lil urea and pass hydrocarbon through it to see if it warms.

Jimmymajesty - 3-7-2010 at 09:35

The nitric acid warmed after urea treatement as I'd expected, so I poured about 150ml cc H2SO4 to 100ml ccHNO3 and bubbled the CH into the mixture. Fortunately there was not any NOx produced as can be seen on the photos.. the brown was taken from pure nitric + CH, the colourless was taken from the H2SO4+HNO3 mixture, the acid mixture only slightly warmed when CH was being passed through it, so I will definitely continue the experiments with that.

Attachment: CH HNO3 mixer.doc (236kB)
This file has been downloaded 1052 times

Melgar - 3-7-2010 at 13:03

When I was doing this experiment, I got an aldehyde smell when I turned up the temperature too high. Typically, it was a combination of formaldehyde and acetaldehyde. My glass tubing was either 4mm or 5mm in diameter, and I never got any violent reactions. A few times I saw jets of flame shoot through it when nitric acid would condense in the tube leading from the nitric acid bottle to the reaction tube. That would cause some liquid nitric acid to get in the reaction tube and make the flame jet.

Are you sending the nitric acid/butane mixture through a 1mm tube at any point? That could make it explode due to a buildup in pressure and the higher boiling point of butane. Propane seems like it'd be a bit safer as it would have less tendency to be in a liquid phase outside of its container.

Jimmymajesty - 4-7-2010 at 07:00

You can avoid the small explosions by sloping the initial part of the tubing in such a way, that any condensed nitric will flow back to the bubbler. I do not think personally that is represents any danger.

As for the small diameter of the quartz tube, see attached photo

I think that was the study of gas phase nitration on smallest scale ever, the bubbler capacity is less than 5ml, I make it explode many times, and it only made sound but did not crack.

I am currently working on implementing the cooling and protection apparatus outside of my lab, I prepare to the worst, 250ml nitric is not something that I would fuck around with carelessly.

Unfortunately lighter filler gas is my only sourse of hydrocarbons, except for some other exotics

Attachment: small scale.doc (89kB)
This file has been downloaded 1135 times

Melgar - 4-7-2010 at 11:43

You don't have those little propane tanks for blowtorches where you are? If you have a slightly larger diameter tube, it'd probably be safer to use that, since you'd be less likely to get a pressure buildup behind the tube. That narrow tube might also have too much surface area. The literature did say a high surface area to volume ratio could cause oxidation instead of nitration, although that may depend more on the tube material.

Jimmymajesty - 4-7-2010 at 21:40

I am going to use d=1cm glass tubing. I asked the glassblower to make it from such a long tube that eventually the tubing capacity would be about 200-250ml. I have not checked its capacity yet, and I think it does not matter, because you can adjust the temperature and the flow rate anyway. And literature suggests 0,1-20sec residence time, which means it is not that important.

I am going to adjust the temperature first, and when I get some product, continue with the flow rate.

Propane tank for blow torches are mainly contains the same gas mix, I checked it, no pure propane. but I also does not worry about that, as my goal is hydroxylamine.

Seemingly there is not much thing I worry about, there is only one, the yield

I foreseen that, after a number of cans I will only get 10-20ml impure product

Nicodem - 7-7-2010 at 01:02

Substrates other than alkanes can also give nitroalkanes upon radical nitration in the gas phase. For example, nitration of acetone with NO2 in the gas phase gives a mixture containing nitromethane as the only nitro compound and acetic acid as the main product (see US4517393). Even though the yield is poor, it should be safer to run than nitrations using HNO3 on alkanes, though it might not work well at 1 atm.
Furthermore, even alcohols, ethers and carboxylic acids can be nitrated in the gas phase to give nitroalkanes in most cases (see JACS, 76, 2692–2694 and references therein).

Jimmymajesty - 7-7-2010 at 10:15

The acetone one would be nice. I am playing with the idea ever since took up this project of using alcohol, acetone and the like as a carbon source, but I am in short of image of workable setups.

My idea would be to use an Y element, one arm would be for the alcohol, and another for nitric.
Nitric acid would simply be heated by a mantle, and the acohol would be evaporated by dripping it into a heated quartz tube. Problems that I can see are that the nitric acid would be kept near its boiling point for hours, so a lot of NOx would be generated instead of HNO3 vapour.
Also the flow rate should be relatively fast at each feed to keep a constant mole ratio, so the reactants wouldnt spend much time in the hot tube which means lower reaction temp.
To keep a constant mass flow by dripping something, is also problematic.
The mixing of the two reactants at the initial stage of the hot tube would also be probably inadequate. I fear that without mixing I simply burn the nitric then pass through alcohol and water vapour.

Do you guys have some nice idea that would eliminate all these problems?

watson.fawkes - 7-7-2010 at 11:37

Quote: Originally posted by Jimmymajesty

Do you guys have some nice idea that would eliminate all these problems?

For constant reagent rates through a drip orifice, use peristaltic pumps with variable rate drives. This will get you close enough in ratio.

For a reaction chamber, use a long, vertical tube. Introduce alcohol vapor at the bottom and have a gas takeoff on the top that contains unreacted alcohol and all the reaction products. Introduce nitric acid through a spray nozzle at the top in very fine droplets. Collect unreacted liquid acid at the bottom of the tube. You'll might want a condenser or cold finger in the dead space below the inlet to reduce NOx vapor pressure.

I've addressed the mixing issue, in part, with the counter-current flows that this apparatus has. The reaction tube should be, at the least, insulated and probably also heated. Standard glass tube lengths from the factory are 120 cm, or about 4 feet, and I'd start with a single full length. You could use two of them in a room with high ceilings before you need to consider special building construction.

Jimmymajesty - 12-7-2010 at 07:11

Before the large scale test I also conducted a small scale test with the H2SO4+HNO3 mix, it worked equally well again HCHO and a peculiar smell at some point.
I measured the bubbler and the gas can weight and measured them after 15 and 45 min of operation. Based on the results the CH/HNO3 mole ratio is well above infinite.. 59g propane butane mixture vaporized only one g HNO3, after the bubbler continuous HNO3 fumes were escaping though. After these experiments, I assembled the setup that can be seen in the attachment. (everything was grounded glass jointed except the connection between the two condensers).
The reactor capacity was about 200ml d=1cm. The furnace was made of two hotplates welded opposite to each other (each hotplate wattage was 1000W) and temperature controlled. The first condenser was a spiral type the second an allihn type, the first only cooled the gas mixture the second condensed back any vaporized stuff.
I poured ~150ml cc HNO3 and 150ml cc H2SO4 into the bubbler and waited till it cooled.
I started to heat up the furnace and at about 100°C I attached a CH can to the end, to flush the air out of the setup.
Then I attached the can to the front part and slightly opened it, waited till the temp of the furnace reached 380°C, at 250°C the brown fumes after the reactor tube disappeared, so probalby the flow rate was at its optimum at that temperature. At 380°C I could smell the carrot like smell again, which I think the pyrolysis products of the nitroparaffin, so I set back the SP of the controller to 350°C and adjusted the CH flow in such a way, that the brown fumes had just disappeared. At this point a peculiar smell could be noticed at the outlet of the second condenser, It was like isopropyl nitrite, a condensate is started to drip into the flask of the first condenser, with a rate about one drop/25 sec. The condensate separated into two phase, but they reacted with each other since the bottom of the flask warmed. This was probably due to the formed HCHO and HNO3 made it at the heating up period into the first receiver flask.
After about 30min I sucked up the condensate from the first flask with a syringe, then washed with water, and smelled, its smell was between menthol and nitro toluene, or rather between paraldehyde and nitro toluene, it was a pleasant smell.
In the second receiver flask only oxidized organic stuff was present which were completely dissolved upon addition of water.
I lit a couple of drops with open flame and it burned with a nice grey colour.
I do not recommend to reproduce this experiment, since it is low yielding, especially at these circumstances. It was only good for get some product to smell it.. I did not heat the bubbler though, by which I think I could attain better results. The explosion hazard problem should be solved by lowering the bubbler head space to zero without HNO3 droplets being sprayed into the hot tube, any ideas on this?
BTW the HNO3+H2SO4 mixture, also heated on its own, it was at about 35°C at the end of the experiment, also I do not think that the nitric could be regenerated from the mixture, I suscpect that there is a lot of semi oxidised CH crap in the mixture that would cause serious frothing upon heating.
Watson interesting approach

I tried that too, but how can you make an even spray, that will be volatilized before falling into the high temp CH vapours? Its seems to be a problem that only industrial bastards can solve over a designer table, I took a 1m long quartz tube and wounded some kanthal wire to the bottom, then I heated the bottom and slowly flooded the bottom of the tube, in such a way that a reflux of CH developed, (I could only hold this state for a min though, then overflow, etc.) during that short time I tried to drip, spray, pour HNO3 into the tube but this always resulted in a cracking noise & barking dog sound..

Attachment: GP nitration exp setup.doc (265kB)
This file has been downloaded 1030 times

zed - 12-7-2010 at 12:26

Considering that the industrial methods usually employed are pretty tough to conduct with home made stuff... Once again, I might consider some alternative.

IF Shulgins procedure for de-constructing the B-Nitro-propene to produce Myristicin Aldehyde and Nitroethane is applicable. Then, the nitration of styrene with I2/NaNo2, in ethylene glycol, to produce B-Nitrostyrene....might be a good starting point, to produce Nitromethane and Benzaldehyde.

I can easily and cheaply obtain all of the ingredients, and solvents. And, the yield of Beta-Nitrostyrene is purported to be about 80%.

With luck, refluxing the resultant B-Nitro-Styrene with N-Methyl Benzylamine will produce the Benzaldehyde-imine.....Plus very pure Nitromethane as gas.

High grade Nitromethane, and an equivalent amount of Benzaldehyde should be recovered (After performing hydrolysis on the imine). I can also recover and recycle my Iodine and N-Methyl-Benzylamine.

Likewise, if this Nitration could be performed successfully on Iso-Eugenol , The deconstructed Nitropropene would yield Vanillin and Nitroethane. I'm not sure if this nitration can be performed on Iso-Eugenol.....Maybe not.

http://www.erowid.org/archive/rhodium/chemistry/nitryliodide...

[Edited on 12-7-2010 by zed]

[Edited on 12-7-2010 by zed]

[Edited on 12-7-2010 by zed]

Nitroethane from ethanol and nitric acid

madcedar - 19-9-2010 at 00:11

Since you are in the mood for experimentation here is a patent for making nitroethane from ethanol and nitric acid (and other useful information).

Attachment: nitroethane pat4431842 (ethanol and nitric acid).pdf (257kB)
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Attachment: Nitroethane, Properties and Azeotropes.pdf (139kB)
This file has been downloaded 1950 times

Attachment: Nitroethane, Purification by Azeotropic Distillation US3480517.pdf (118kB)
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arsphenamine - 19-9-2010 at 17:10

Quote: Originally posted by zed

IF Shulgins procedure for de-constructing the B-Nitro-propene to produce Myristicin Aldehyde and Nitroethane is applicable. Then, the nitration of styrene with I2/NaNo2, in ethylene glycol, to produce B-Nitrostyrene....might be a good starting point, to produce Nitromethane and Benzaldehyde.

Maybe I'm too easily amused, but the thought of a "reverse Henry Reaction" is chortle producing.

Here someone has a perfectly good illicit precursor and they want to disproportionate it back into Henry reactants.

stygian - 19-9-2010 at 17:17

It's a more interesting idea if you could make it work with 2-nitropropene.. and fancied working with 2-nitropropene

zed - 20-9-2010 at 01:33

Ummmm. Well, P-Propenyl anisole and Iso-Eugenol, are inexpensive and fairly worthless as precursors.

Using them to generate, difficult to obtain Nitroethane, ala Shulgin....has some merit.

Additionally , Vanillin and Anisaldehyde, have their own uses.

Shulgin ripping apart the MMDA skeleton to produce Myristicin Aldehyde, may seem
crazy to us, but it suited his goal. And, it served to reveal a potential Nitroethane synthesis, that could prove very handy in this era when Nitroethane is very tough to come by.

Waffles SS - 1-1-2011 at 12:35

Quote:

Nitromethane can be prepared by the action of dimethyl sulfate on potassium nitrite
Walden, Ber. 40, 3216 (1907)

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0401

Anyone know detail of this reaction?

franklyn - 4-1-2011 at 19:35

Quote: Originally posted by Waffles SS

Nitromethane can be prepared by the action of dimethyl sulfate on potassium nitrite
Walden, Ber. 40, 3216 (1907)

Anyone know detail of this reaction?

read second half here
http://www.sciencemadness.org/talk/viewthread.php?tid=13633&...
A good reason not to make that way
http://www.sciencemadness.org/talk/viewthread.php?tid=1608&a...

http://www.sciencemadness.org/talk/viewthread.php?tid=1608
http://www.sciencemadness.org/talk/viewthread.php?tid=2995
http://www.sciencemadness.org/talk/viewthread.php?tid=9570

.

MeSynth - 30-8-2011 at 20:25

Quote: Originally posted by 497

This patent might be interesting to some here. It is a patent that gives the conditions to produce a mixture of 83% nitroethane and 17% nitromethane by vapor phase nitration of propyl nitrite with 50% HNO3 vapor at 400*C (or NO2 at 300*C), at atmospheric pressure. Interestingly, they use an aluminum tube immersed in a molten salt as the reactor. It is advantageous because it results in a simpler mixture of products that should be much easier to purify... Assuming you can get n-propyl alcohol, propyl nitrite is ultra easy to synthesize.. The extra carbon is lost as formaldehyde. If you wanted nice pure nitromethane, you could use isopropyl nitrite instead, which results in only nitromethane (and acetaldehyde byproduct).

[Edited on 18-6-2010 by 497]

US3209038

I have tried to work out how this would be done. Saftey is a major issue due to n-propyl nitrite being an explosive. Due to the explosive nature of the reactants I would not hand operate this and would rather operate the air pump from behind a concrete wall. Other than this explosion hazard I feel no threat and have drawn out the first part and the second leaving out the n-propyl nitrite stage since I'm not certain about what they mean in the patent when they say the n-propyl nitrite was allowed to enter a stream of 50% nitric acid vapor that has been preheated to 260* C. The pictures have been added as attachments.

My best guess is small amounts of n-propyl nitrite will boil out when the nitric acid vapor heated to 260* C. is passed through causing just the right amount to vaporize and mix with the gas.

The missing stage is where the nitric acid combines with the n-propyl nitrite before entering the reactor.

497 - 31-8-2011 at 01:55

PrONO has a terrible oxygen balance on its own, it would be tough if not impossible to detonate in my opinion. Mixing it with HNO3 would improve the OB and sensitivity no doubt, but it shouldn't be hard to avoid that fully by using an inert gas to dilute the gas mixture. Concrete walls are always a good precaution though if you have them. It shouldn't much need hands on attention anyway.

I'm not certain, but I would bet that the mixture of HNO3, H2O and RONO proposed in the patent forms an equilibrium with ROH, NO, and NO2 via 2RONO + H2O <---> 2ROH + NO + NO2.

Since NO2 can be formed from air by electric discharge pretty easily, you might be able to have a continous process where the output from the electric discharge is fed into an absorption column/bubbler filled with liquid ROH + H2O. These react to form RONO + HNO3, at least until too much HNO3 builds up. Then the ROH + RONO + HNO3 + H2O from the NO2 absorber is dripped into a vaporizer and piped into you reactor tube. Supplemental HNO3 could also be added from a separate NO2 absorber filled with only H2O if need be. HNO3 recycled back from the product mixture would likely be sufficient though.

Electricity, air, water, and an alcohol in, nitroalkanes and aldehydes of your choice out. Sound pretty elegant to me. The inert gas could hopefully be recycled. CO2 is pretty cheap though. I'd be interested in using it for both the acetaldehyde + nitromethane, and the formaldehyde + nitroethane possibilities.

Not sure about the best ways to process the end mixture of HNO3, ROH, water, nitroalkanes and aldehyde(s). Nitroethane does form azeotropes with n-propanol and water for sure. Maybe an extractive distillation could help?

What do you think?

AndersHoveland - 21-9-2011 at 23:46

The vapor phase nitration of propane with nitric acid at 420degC produces various nitroalkanes in 40% yield total.
The yield for nitromethane is only 4%, for nitroethane 10%, for 2-Nitropropane the yield is 16%.
The various nitroalkanes are then separated by distillation. Nitromethane boils off first at 101degC, then nitroethane at 114degC. The vapor-phase nitration can alternatively be done with nitrogen dioxide, giving better yields, with the additional advantage that the products contain less 2-nitropropane.

2-Nitropropane boils at 120degC. 1-Nitropropane boils at 131degC. 2-Nitropropane is a carcinogen, breathing of its vapor should be avoided.

[Edited on 22-9-2011 by AndersHoveland]

497 - 22-9-2011 at 03:47

I don't see how effective separation of of nitromethane, nitroethane, and nitropropanes can be accomplished with their boiling points all being within 30 degrees of each other.. Even worse is that nitroethane and 2-nitropropane are within 6 degrees or each other.. I think a method that produces nitroethane more selectively would be much more useful. Unless there is a magic bullet way to purify it?

simba - 22-9-2011 at 07:53

Quote: Originally posted by 497

I don't see how effective separation of of nitromethane, nitroethane, and nitropropanes can be accomplished with their boiling points all being within 30 degrees of each other.. Even worse is that nitroethane and 2-nitropropane are within 6 degrees or each other.. I think a method that produces nitroethane more selectively would be much more useful. Unless there is a magic bullet way to purify it?

Maybe they can be purified by freezing...nitromethane freezes at −29 °C, nitroethane at -90 °C, and I don't know about nitropropanes.

AndersHoveland - 22-9-2011 at 11:30

It might be better to do a vapor phase nitration using ethane, or possibly even methane (natural gas), to avoid formation of hazardous 2-nitropropane.

Typically, when two similar compounds have very close boiling points, the mixture needs to be distilled several times repeatedly. This can generally minimize impurities in the separated compounds.

For example, the portion that initially distills off from a mixture of nitromethane and nitroethane would be redistilled again, and the portion that distills off from the second distillation would be nearly pure nitromethane, although some of the nitromethane got left behind with the nitroethane.

The industrial process only uses propane because nitroethane, which is used as an industrial solvent, actually sells for a higher price than nitromethane. Nitromethane is considered the byproduct.

[Edited on 22-9-2011 by AndersHoveland]

Alastair - 25-9-2011 at 01:23

''For example, sodium (nitrite) and potassium nitrite reacting with iodomethane would produce mostly nitromethane, with methyl nitrite as the minor product''
Source: wikipedia. ref: Donald L. Pavia, Gary M. Lampman, George S. Kriz (2004). Organic Chemistry. 2. Mason, Ohio: Thompson Custom Publishing. ISBN 0030148138. OCLC 236055357 But i couldnt find the ref.

Could this be applied to iodoethane?
Or maybe nitroethane can be separated as a side product from nitrite syntheses via alcohols + NaNO2 (or N2O3) ?

simba - 25-9-2011 at 09:41

Quote: Originally posted by Alastair

''For example, sodium (nitrite) and potassium nitrite reacting with iodomethane would produce mostly nitromethane, with methyl nitrite as the minor product''
Source: wikipedia. ref: Donald L. Pavia, Gary M. Lampman, George S. Kriz (2004). Organic Chemistry. 2. Mason, Ohio: Thompson Custom Publishing. ISBN 0030148138. OCLC 236055357 But i couldnt find the ref.

Could this be applied to iodoethane?
Or maybe nitroethane can be separated as a side product from nitrite syntheses via alcohols + NaNO2 (or N2O3) ?

yeah...iodoethane or any other haloethane will yield nitroethane.

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