Sciencemadness Discussion Board

Nitromethane extraction

plasma - 21-5-2002 at 11:49

I have one gallon of fuel for r/c cars witch
contains 15 % nitromethane, 18 % oil and the rest is methanol. How can I extract the nitromethane. When mixed with water I can remove the oil with a eye-dropper, but is it possible to remove the methanol ?

Polverone - 21-5-2002 at 11:50

It will be hard to get pure nitromethane from your fuel. Methanol evaporates considerably faster than nitromethane, so I'd first just expose it to the air and see when the volume of the liquid had dropped about the right amount. At that point, I don't know exactly how well the oil, nitromethane, and remaining methanol will separate. Water will dissolve up to 10% nitromethane, so you may have considerable losses if you need to add water to separate the oil. Water and nitromethane have close to the same boiling point (not that I'd boil nitromethane) and evaporation rates. So you may only be able to get oily nitromethane.

plasma - 21-5-2002 at 11:50

Thanks for your replies. I will try your first suggestion, and let it evaporate, I think it will work. But when it has evaporated down to 33% of the original volume, it is more oil than Nitromethane.

PHILOU Zrealone - 21-5-2002 at 11:51

So your racing fuel contains:
15% NM (CH3-NO2)
18% Oil (X-YZ)
67% Methanol (CH3-OH)
You first need to know properties off the components to be able to separate them:
1)All are soluble in each other
2)NM:BP= 101°C; MP= -29°C
Methanol:BP= 65°C; MP= -98°C
Oil BP>200°C; MP=? usually not far from ambiant T or close to freezing Temp!

With this you can conclude that distillation can be the way to go Methanol will leave the system; then the NM and finally the Oil will remain! You can also conclude that Freezing is a good way to get the oil out, and then the NM...(it is a special kind of cristallisation separation); Carbo-ice allows you to go as low in T as -80°C when in methanol or aceton (methanol will remain liquid!).I would first try deep freezer at -20°C to see if you can get hold of the Oil!

3)Oil water solubility is low; so does NM solubility; methanol is 100% miscible with water.
So water could be a way to go; but NM is a little soluble in water and very soluble in methanol (so its solubility can be good in a methanol/water mix!)
Assuming you have 1 liter of fuel:
180ml of oil
150ml of NM
670 ml of MeOH
By adding 6,7 Liter of water, you will decantate a lot of oil as an upper layer (probabily 90% of it), but also a part of your NM (maybe 50% of it) stil 50% will remain in solution; this is a poor choice!
You can add a little acid strong acid to diminish solubility of NM but still it wont help a lot!

4)
Oils are rather inert towards acids, but may react with bases to make soaps (depend on the oil of course; parafin oil is inert).
R-CO2H + NaOH --> R-CO2Na + H2O
Soaps are much more soluble in water than the original oil!
Original oil (if soaponifiable) can be regenerated by strong mineral acids!
R-CO2Na + HCl --> R-CO2H + NaCl

NM forms "explosive salts" with NaOH or with KOH and NH4OH; those salts are brown/orange and form slowly when biphasic (but it can increase speed with heat (runaway) and be quite fast when both base and NM are in the same phase what can be the case here since methanol is amphiphile solvant....reaction is quite exothermic as all acid-base neutralisation! Salts are usually unsoluble in methanol (most of them) and weakly soluble in methanol/water (I found recently that methanenitronate salts are weakly soluble in methanol and can be easily separated.
Nitromethane is inert towards acid exposure (except long boiling exposure to H2SO4)

Methanol is inert towards bases but forms esters with acids!

From this you see:
That treating your batch with acid will give esterification of methanol and leave NM and oil unattacked:
Amongst interesting esters are:
-Nitrous ester CH3-ONO is gaseous at ambiant T and forms spontaneously when 30%HCl and NaNO2 are dropped in methanol (Flamable and liable to make gas explosion) it will bubble a lot!
CH3-OH + HCl + NaNO2 --> CH3-ONO + NaCl + H2O
This process is interesting but toxic due to NOx (HNO2 free some of it)and might be expensive if you don't have cheap sources of NaNO2/HCl.
Oil remains unafected and NM too; as a conclusion, water is formed, NaCl also and methanol leaves the batch- keep the batch T arround 10°C!
-Methyl chloride (it is also gaseous) but formation is quite slow and needs HCl conc and ZnCl2 as a catalyst + heating arround 60°C
CH3OH + HCl + ZnCl2 --> CH3Cl(g) + H2O + ZnCl2
Here you have a catalytical qtity of ZnCl and H2O; oil and NM remain unaffected!

You see also that another alternative is to treat the batch with saturated NaOH, KOH or NH4OH solution (drop by drop);(oil may soaponifiate but will remain in methanol/water solution) under stirring and cooling (30°C max)! When base addition is finished and the T starts to drop,allow the batch to cool down on its own, cristalls of Na,K or NH4 Nitronate should form and precipitate.If they don't form, allow to cool further with the help of ice cold bath!(Normally it should precipitate if you have a saturated solution of base I have done it many times).
Those cristalls are no pure nitronate but complexes of NM with it so don't be alarmed they don't explode unless very dry and hot in contact with a flame or a strong shock!
Filter them.And drop them fast (to avoid any drying) in 10 times the amount of water (or more) until fully dissolved.Then add dropwise under stirring and strong cooling medium conc strong acid (H2SO4 40%, HCl 33%, AcH 100%) (max 30°C)It is a neutralisation reaction between a strong acid and a strong base, so it heats a lot!A yellow layer of NM will form on top of the the beacker, add acid until the water that was initially black brown turns orange, then yellow test for acidity with lithmus; if positive allow to stand with a cover on top until transparent!
CH3-NO2 + NaOH <-=> CH2=NO-ONa(blackbrown)+H2O
CH2=NO-ONa + HCl --> CH2=NO-OH(yellow) + NaCl
CH2=NO-OH <-=> CH3-NO2
nitronic form of NM is soluble in water while its non nitronic form (the most stable) is nearly unsoluble.
You should then have two layers; test them for flamability; only the NM will burn (a bit like ethanol or nitroglycerin flame)!

With all this you can make a separation tree following your abilities!

PH Z

plasma - 21-5-2002 at 11:52

I'm a bit confused, have I done it right ?
When saturated NaOH is dropped in the fuel when cooling and stirring, the solution gets pink and a large amount of very small cristalls appear. When they are filtered and dumped in water and fully desolved, the solution turns yellow. When adding 30% HCl to the solution under stirring and cooling, the solution turns dark red. Oily droplets form slowly on the surface. (They don't burn)
BTW the oil is none-petroleum

Thanks

plasma - 21-5-2002 at 11:52

Is destillation of NM safe ? It seems crazy to destill a high explosive.

madscientist - 21-5-2002 at 11:53

I would think that would be dangerously risky.

plasma - 29-5-2002 at 14:06

If destillation is so dangerous why would PH Z say this :
"With this you can conclude that distillation can be the way to go Methanol will leave the system; then the NM and finally the Oil will remain"

madscientist - 29-5-2002 at 15:47

When I heard "distillation" from you, I was thinking of you heating nitromethane with a propane burner. :)

plasma - 30-5-2002 at 09:16

Please don't think like that.
I have ordered some real equipment (condenser, hotplate, flasks, beakers etc.). I think I will get the pack over the weekend. Then I will start with all the "complex" sythesis. (like NM dest.)

"Professional" destillation of NM will be all right, right ? :)

Polverone - 30-5-2002 at 11:55

Possibly. It may still be risky. Go to groups.google.com and search sci.chem for nitromethane distillation. There was a fairly long thread about this a while ago - Philou was one of the primary contributors.

It sounds like you are really making progress in chemistry, by the way! Only a couple of months ago you had virtually no chemical knowledge and were trying to improvise things from toilet bowl cleaner. Now you seem to have been doing some reading and you're getting some real equipment. Way to go! I hope you remain safe as you continue to expand your horizons of knowledge.

Pyrex - 8-6-2002 at 08:58

I don't think that the distillation of NM is more dangerous than distilling sth highly flammable like gasoline or so. Otherwise they wouldn't sell it pure (think of a building with 100l drums inside on fire). The stuff won't detonate unless it is sensitized or a big booster is used.

Madog - 8-6-2002 at 09:26

i have a video of some pure NM being detonated with a booster of tetrly. u can also detonate it easier if you mix it with H2O2 or something like flour to give it a lower densitity

distilling nitromethane

dr. Vitus Verdegast - 15-7-2002 at 06:22

Use vacuum distillation if you really want to be safe. You only need to warm it around 50deg. with the average fridge pump or aspirator, so a warmwaterbath will be fine. Be sure to throw in some boiling rocks.

Vac. distilling is not that more difficult if you already know how to perform it at atm.pressure, but you should read up on it fiorst.

PHILOU Zrealone - 15-8-2002 at 13:17

NM boils at 101°C; unless you boil it without condenser/cooler or boil it over ammonium nitrate or over a sensitive primary or over an amine or strong base like NaOH/KOH/LiOH/...
there is no risk of fire/explosion/detonation.
There is less risk in distillating NM than in distillating ethanol or methanol.
You can set it on fire, it simply burns like ethanol.Since it is flamable liquid, its vapour with air form explosive mixture (like many organic solvants).

Enjoy!
Plasma, did you tried freezing the mix to take the oil away?

plasma - 24-8-2002 at 12:57

I did try freezing, but it didn't work very well.

BTW, the equipment I ordered 2 months ago arrived today. :D

PHILOU Zrealone - 8-9-2002 at 09:59

Great!:)

Chambered - 27-10-2002 at 10:27

Nitromethane is easily and safely disstilled at atm.It does however form a azetrope with methanol,the MeOH/nitro azetrope will come over first and then pure nitro will come over resulting in quite a loss of product to the azetrope.Guess it depends on the purity you require.btw the azetrope will be about 8%nitro and the rest MeOH.Peace,Chambered.

re

Haggis - 27-12-2002 at 23:23

When you said NM the first thing that came to mind is ANNM. If this is what you want, wouldn't it be good enough to evaporate off the methanol and add the oil/NM solution to the AN? ANFO and ANNM are both secondaries, so wouldn't a combination of the two just make it a bit more sensitive, yet serve the purpose you intended? Oh well, that is only assuming that you were working for ANNM. I hope my reply is not out of line for the reagent section.

Theoretic - 10-11-2003 at 08:32

Nitromethane is in fact very hard to ignite with a match, and if it does burn, it does so with a lazy blue flame. It does detonate on shock though.

Nitro distillation

tryptamine - 26-11-2003 at 22:13

Well if you take that oil formed from re acidification of your sodium/ nitro salt and distill it you will get pure nitro.

The sodium salt is quite sensitive so I don't reccomend doing this method.

However it is not the distillation that is dangerous, the distillation is safe and easy under atmospheric conditions. This is not a sensitive high explosive! Man up.

You need to find 50% or better nitro fuel, then distill this, your forerun is an azeotrope of nitro and methanol, something like 8/92, then over comes pure nitro, and you leave the oil in the flask.

Simple, not dangerous in the least, the explosive nature of nitromethane is overstated.

I just noticed that I was beat to the punch, but hell I've done it, so go for it!

[Edited on 27-11-2003 by tryptamine]

NITROMETHANE FRACTIONAL DIST. IS SAFE!!

Hermes_Trismegistus - 28-11-2003 at 14:19

relatively safe anyway!!!

From racing, I can safely say that nitromethane is VERY safe, It has a very high flashpoint, so vapours in air are quite difficult to ignite, and it is not a very energetic compound, (far less than gasoline)

as for detonation, try not to dip strings of blasting caps into it and you should be OK!;)

the reason it is used in racing is to allow the addition of vast amounts of raw fuel without "drowning" the spark plug.

I think it had something to do with increasing the amount of available oxygen in the cylinder, and that it led to its use as a component of liquid explosive, not because of its inherent instability!!!
:)

Hermes_Trismegistus - 28-11-2003 at 14:20

not because of its inherent instability!!!

correction....because of ANY inherent instability (its pretty damn stable)

tom haggen - 12-2-2004 at 01:37

Theoretic, How strong of a shock wave does it take to detonate 100% pure nitromethane?

Tacho - 12-2-2004 at 02:27

Nitrometane distilation from racing fuel is very straighfoward. It works fairly as a classic simple distillation but to get good results you should try to fraction it as much as possible (long column, packing...). You have to use a decent distillation setup with a thermometer. And no open flames! Eletric heating!

First the temperature remains stable at the bp of methanol. You have only methanol coming. This is by far the largest fraction.

Then temperature start rising. You are now collecting a mix of methanol and Nitromethane. This is a large fraction, don't discart it, redistill.

Than temperature stays at the bp of nitromethane. You are now collecting nitromethane.

Then you stop getting condensates and your oil begin to smoke a bit. Turn the heat off.

I don't care what theory says. This is what happens in the real world.

If you didn't fraction your distilation enough, a second distilattion will give you almost pure nitrometane.

I got 150ml of rather pure nitromethane out of a gallon of 10% nitro fuel.

Extractions are messy and useless.

Good luck.

Theoretic - 12-2-2004 at 08:10

Well, a blow with a hammer will do it (an open puddle, where part of the nitromethane will become confined, will detonate, a glass vessel, for example, will break and no confinement will be achieved, while a metal vessel will deform and do the job - I extrapolate). Drums for nitromethane are made to deform in a special way and/or break altogether to prevent confinement.

axehandle - 19-2-2004 at 14:36

And for goodness sake <b>DON'T USE A PROPANE BURNER!</b>

I did once, and underestimated the temperature. The glass vessel melted. Luckily it didn't contain anything combustible / explosive.

tom haggen - 19-2-2004 at 16:18

I'm no expert but I almost find it hard to believe that nitromethane will detonate from the blow of a hammer. As soon as I get mine dried i will try with a small drop. Further more, If Nitromethane is sensitized by NH4NO3 wouldn't that make ANNM easier to detonate than Nitromethane? Hence, you can detonate ANNM with the blow of a hammer?

Tacho - 20-2-2004 at 04:54

Aldrich catalog says NM is flamable, doesn't say nothing about explosive. Anyway, it also doesn't say ammonium nitrate is explosive.

Merck index also says nothing about NM beeing explosive, it says it forms explosive sodium salts, flammable in contact with water. Merck says clearly ammonium nitrate is explosive.

My NM does not explode under a hammer blow.

My quick internet searches about nitromethane don't show any reliable source saying it explodes. It acts as a souce of "packed" oxigen source for fuels in race cars. It seems the extra power is not achieved by any explosive property.

Good luck again. I wish you (safely) prove me wrong.

tom haggen - 20-2-2004 at 09:33

I'm under the impression that nitromethane is definitely an explosive. It it just much less shock sensitive than theoretic says.

The_Davster - 20-2-2004 at 18:46

Quote:
Originally posted by tom haggen
I'm no expert but I almost find it hard to believe that nitromethane will detonate from the blow of a hammer. As soon as I get mine dried i will try with a small drop. Further more, If Nitromethane is sensitized by NH4NO3 wouldn't that make ANNM easier to detonate than Nitromethane? Hence, you can detonate ANNM with the blow of a hammer?


I believe that the NM sensitizes the ammonium nitrate, not the other way around. ANNM is sensitized to the point where it will detonate by a cap(unlike AN by itself) but not by a shock like a hammer blow.

tom haggen - 20-2-2004 at 18:59

I could have sworn that I read somewhere that Nitromethane is sensitized by NH4NO3. I guess don't believe everything you read.

[Edited on 21-2-2004 by tom haggen]

Nitromethane

Dream of the iris - 24-12-2005 at 20:35

I have some store bought nitromethane that I want to purify. I tried to create nitronates of the nitromethane using a NH4OH solution, but it failed. I measured out about 100mls of the store bought nitromethane/methanol solution and added roughly 20mls or more of a dilluated ammonium hydroxide solution to the mix. I set the mix in an ice bath. The solution after 24+ has blue oily spots (the nitromethane solution was blue to begin with) suspended in a white (assuming this is the hydroxide mixed with the nitromethane/methanol) solution.

The nitromethane/methanol solution contains 33% nitromethane.

Any ideas as to why this happened and what I can do to improve it?

chemoleo - 25-12-2005 at 12:32

Actually, this is something I meant to test myself, precipitation of nitromethane with i.e. NaOH, to extract it from racing fuel.

Well, a) I'd use NaOH, not ammonia. It's a stronger base, and no funny reactions can occur.
b) I'd make sure to calculate that an EXCESS is present (of NaOH).
c) I'd either dilute first with at least 10x the amount of water. I should think that way you already get rid of most of the methanol, whjile insoluble NM and other oils float at the top (it roughly dissolves at 7 mole percent, so most is insoluble).

Then, extract with H2O once more (shake vigorously), let it settle, and add NaOH. The nitronate should precipitate. This then is extracted, washed more with water, and the correct amount of acid is added. NM should reappear as an insoluble oil. Beware, nitronate is very flammable.

Let us know how you get on.

DDTea - 25-12-2005 at 16:31

Quote:
Originally posted by chemoleo


Well, a) I'd use NaOH, not ammonia. It's a stronger base, and no funny reactions can occur.
b) I'd make sure to calculate that an EXCESS is present (of NaOH).
c) I'd either dilute first with at least 10x the amount of water. I should think that way you already get rid of most of the methanol, whjile insoluble NM and other oils float at the top (it roughly dissolves at 7 mole percent, so most is insoluble).

Then, extract with H2O once more (shake vigorously), let it settle, and add NaOH. The nitronate should precipitate. This then is extracted, washed more with water, and the correct amount of acid is added. NM should reappear as an insoluble oil.



Adding one more step to this... First, add a lot of H2O and remove any oil you can--either with an eye dropper, separatory funnel, or whatever. If you don't, the oil will saponify when you add NaOH and just make things very messy (it's hard to clean off, too); not to mention, it will be very hard to collect your precipitate.

neutrino - 25-12-2005 at 19:01

How would you separate the oil and NM? They are both insoluble and will be in the same layer at the start.

chemoleo - 25-12-2005 at 19:04

by reacting the emulsion in water with NaOH......

neutrino - 25-12-2005 at 20:10

The way I read it, he was describing some physical means of separation, not a chemical one. I may be wrong, though.

chemoleo - 25-12-2005 at 20:38

I see what you mean now.
Samosa worries about saponification with NaOH of oils OTHER than NM. Those other oils are obviously not seperable from NM by dilution in water, as both will form an insoluble layer. So you take that layer, make an emulsion with H2O and add NaOH (correct amount, this can be calculated as the conc of NM is usually given), and the NM will react to form nitronate, while hte remaining oil will not react (saponification is not an issue really as saponification requires higher temperatures, long reaction times and so on, while the nitronate reaction is instantaneous).

sparkgap - 26-12-2005 at 02:16

"...Beware, nitronate is very flammable..."

I seem to remember that the reaction between nitromethane and lye was quite violent, but I haven't tried it out. Can you think of any other precautions, chemoleo? I have quite the overabundance of racing fuel at my resthouse... ;)

Alternatively, can anything other than a base extraction be used?

sparky (~_~)

Dream of the iris - 26-12-2005 at 14:35

Yeah, you could esterfy the methanol, but I think that way is harder.

DDTea - 26-12-2005 at 15:07

Quote:
Originally posted by chemoleo
...(saponification is not an issue really as saponification requires higher temperatures, long reaction times and so on, while the nitronate reaction is instantaneous).


I think it's experiment time :P. But I tried something similar to this a year or two ago and got a caustic gunk all over my beaker shortly after I added NaOH to the RC fuel, and I couldn't find anything that would dissolve it.

Anyhow, as was stated already, there would be an oil and an aqueous layer on dilution with water... But Nitromethane is also 'significantly' (quoting an MSDS) soluble in water. So the acid/base route might be a way to recover the NM from methanol/water that would otherwise be disposed of.

The_Davster - 26-12-2005 at 15:33

Perhaps impractical but....
React the mix with bleach to get chloropicrin, separate chloropicrin, react chloropicrin with Fe/HAc, to get methylamine, then oxidize methylamine to nitromethane again.
:P

EDIT: Thanks Samosa, I changed the above to HAc.

[Edited on 27-12-2005 by rogue chemist]

DDTea - 27-12-2005 at 01:11

Quote:
Originally posted by rogue chemist
Perhaps impractical but....
React the mix with bleach to get chloropicrin, separate chloropicrin, react chloropicrin with Fe/acid (either HCl or HAc I forget which), to get methylamine, then oxidize methylamine to nitromethane again.
:P


Wouldn't reacting Chloropicrin with a reducing agent and HCl lead to Phosgene Oxime!? I'm game for that.

But there is a way to get methylamine from chloropicrin...there are a lot of neat, potentially useful reactions that can be done on it.

However, if chloropicrin can be converted back into Nitromethane, this is a very viable answer. I tell you from experience that Chloropicrin is very easy to isolate from this mixture with a simple separatory funnel.

EDIT: here we are, from War Gases:

Quote:
Geisse, with iron filings and acetic acid, obtained methylamine:

CCl3NO2 + 6 H2 --> CH3NH2 + 3 HCl + 2 H2O


Phosgene Oxime is obtained if one uses Tin powder and Hydrochloric Acid; although I remember Zinc powder being mentioned also.

[Edited on 12-27-05 by Samosa]

The_Davster - 27-12-2005 at 12:02

Quote:
Originally posted by Samosa


But there is a way to get methylamine from chloropicrin...there are a lot of neat, potentially useful reactions that can be done on it.



You do have that file that was on the FTP entitled 'chloropicrin'? It goes into much more detail than The War Gasses about the chemistry of chloropicrin. A lot of cool things can be made starting from it, CI4, C(OC2H5)4, KNO2, etc.

Now to oxidize the methylamine HCl formed, what would be the best oxidizer here, something commonly available like permanganate or persulfate would be nice, although whether they would work I do not know.

Dream of the iris - 28-12-2005 at 11:02

Quote:
Originally posted by chemoleo
Actually, this is something I meant to test myself, precipitation of nitromethane with i.e. NaOH, to extract it from racing fuel.

Well, a) I'd use NaOH, not ammonia. It's a stronger base, and no funny reactions can occur.
b) I'd make sure to calculate that an EXCESS is present (of NaOH).
c) I'd either dilute first with at least 10x the amount of water. I should think that way you already get rid of most of the methanol, whjile insoluble NM and other oils float at the top (it roughly dissolves at 7 mole percent, so most is insoluble).

Then, extract with H2O once more (shake vigorously), let it settle, and add NaOH. The nitronate should precipitate. This then is extracted, washed more with water, and the correct amount of acid is added. NM should reappear as an insoluble oil. Beware, nitronate is very flammable.

Let us know how you get on.


I tried that just a little while ago using Devil Lye (100% NaOH). Using the 33% NM solution I had, I measured out 33gs of the NaOH and added it to the diluted nitromethane solution (I used 10X the amount of water like you suggested) and a few seconds later it boiled and began to bubble out of my beaker! I discarded the solution (all over my garage floor. I missed the waste bucket -_-) immediately. Was it because I added too much NaOH too fast? Or maybe because it was 100%?


BTW, the NaOH was solid, not liquid, hence the use of grams :P Perhaps that was a factor?

[Edited on 28-12-2005 by Dream of the iris]

[Edited on 28-12-2005 by Dream of the iris]

neutrino - 28-12-2005 at 11:12

If the amount of NaOH was correct, its form won't matter much. The problem is that you added too much too fast without adequate cooling. Try precooling the NM and putting the beaker in an ice bath when you do the reaction next time. Also, try dissolving the proper amount of NaOH in water first and cooling that. This should eliminate that pesky heat of hydration from the reaction.

chemoleo - 28-12-2005 at 11:37

You need roughly 61 grams nitromethane per 40 grams of NaOH. In other words, you had an excess of NaOH which is not good.

Cooling is essential, and I'd FIRST dissolve the NaOH in water, cool it, and THEN add it very slowly at 0 deg C to the diluted cool NM. The reaction of nitronate formation is known to be exothermic, so beware.

Also, at no time to you need to dry the salt (it's dangerous), just filter the precipitate, wash it with water for a fair bit, and then take the precipitate and add a slight stoichiometric excess of dilute acid - SLOWLY! The acid excess is needed to drive the equilibrium to the left, i.e. where NM is insoluble in water.

Here some quotes from E&W.

By Philou:
Quote:
*saturated ammonia solution gives heat and a dark brown solution of NH4CH2NO2 but :-( I was not able to isolate the salt by evaporation (even in the cold)-I suspect the compound to be very unstable it decompose into its elements maybe due to an equilibrium in solution:
NH4OH + CH3-NO2 <==> NH4CH2-NO2 + H2O.
*saturated solution of NaOH (solid prills) gives a lot of heat (you might expect an explosion or a fire!!!) but the isolated salt don't give interesting results (except if confined and dry).
The NaCH2NO2 is difficult to dry because it picks up water from air. It burns with puffing flammes. I guess it would explode if confined in an enclosed metal pipe and heated by a surrounding heat source like Black powder or Na chlorate/suggar or a fire.
*KOH gives a precipitate with a lot of heat also (fire or explosion to expect without water cooling or if big quantities are made).
Less difficult to dry than the Na salt. Burn fiercely like NC outside and once confined surely it will go boom.
*Ca salt I made has the advantage of being dry, precipitate, burn fiercely and explode when confined (very easy to use).


By Vorion
Quote:

i made Ca(CH2NO2)2 by mixing pure NM with Ca(OH)2 and a few drops of water while stirring. As i didnt want to make big quantities i have now about 0,5g Calcium nitronate. It looks like Cinnamon powder when dry (and pulverized). It was easier to make than NaCh2NO2, which i made about a month ago and dropped because of a strong smell of Ammonia after half a day stored dry, because the temperature is easier to control.
Zaibatsu had some impurities in his product because he used Calciumcarbide. I used pure Calciumhydroxide + CH3NO2 and i do have some bigger crystals in my product, i tried to separate them and they look a bit darker than the other product.

Dream of the iris - 28-12-2005 at 19:08

How big are the nitronates supposed to be?

Edit by Chemoleo: Clarify. HOw big, what, molecular mass? ionic radius?

[Edited on 29-12-2005 by chemoleo]

Dream of the iris - 29-12-2005 at 12:12

Molecular mass. Well, compare nitronates to, say, table salt or something.

Also, I did everything you said, but nothing really happened (no crystals formed) so I let it sit overnight and when I returned there was black liquid in the beaker with no crystals. Maybe I should heat it to speed the process?

[Edited on 29-12-2005 by Dream of the iris]

[Edited on 29-12-2005 by Dream of the iris]

Distilling nitromethane from RC fuel

xwinorb - 12-4-2006 at 10:38

SWIX has a question on distilling nitromethane from RC fuel.

Technique used :

Aproximately 800 ml of RC fuel was washed with 200 ml water, twice, water poured carefully over fuel to avoid emulsion. Top water layer separated. Bottom layer dried with CaCl2 ( this dessicant is used in an Organic Synthesis method for making nitromethane ).

Distilled at RT. Main nitromethane fraction collected at 90 - 101 C. Got 250 g. Compared weight of same volume of water, got 221 g. This yields density = 1.13.

Question :

I have done this twice, both times I noticed some strange yellow byproduct forming on the side of the boiling flask during distillation. Not sure if it is nitromethane decomposing, castor oil decomposing or nitromethane reacting with other ingredient in the RC fuel.

Does someone knows what this is ?

Does this happens when distilling pure nitromethane ?

Any danger ?


This time, I have also extracted the top water layer with DCM, combined with main fraction. But, the DCM BP is raised by the nitro / oil mix, so it does not separate cleanly from the main nitro fraction. I think I would distill it separately next time.

Any suggestions or comments welcome.

daeron - 12-4-2006 at 12:29

it doesnt happen with the pure nitromethane...i doubt that its some byproduct forming, prolly some of the impurities w lower density and higher surface tension. when exactly does this start to happen, on the begining, during the whole or at the end?

if nitromethane was decomposing you would know about it, trust me

Impurity

xwinorb - 12-4-2006 at 14:23

It happens in the middle of the distillation. Started seeing some yellow spots, slowly increasing, a fairly large ammount at the end. Washed away easily with 70 % IPA and soap.

I prefer washing the MeOH with water, then drying the RC fuel before distilling as outlined, because the yields seem better. Otherwise a lot of nitro just evaporates away with the MeOH at the start.

I don't think there is any problem using water, but what about CaCl2 as dessicant ? It is indeed recomended in the Organic Synthesis for nitromethane.

praseodym - 13-4-2006 at 04:31

Shouldn't be a problem since CaCl2 is suitable for drying alkyl and aryl halides, most esters, saturated and aromatic hydrocarbons as well as ethers.

Tacho - 13-4-2006 at 08:52

xwinorb, I would be VERY CAREFUL with those byproducts.

Reading your post, I remembered something I read long ago in the usenet groups (google.groups). Doing a search with +nitromethane +explosive +salts +distillation I found this:

"Distillation of Nitromethane
Todas as 24 mensagens no tópico - exibir como árvore
De: Dave Klein - ver perfil
Data: Sex 15 mar 2002 19:47
E-mail: dpkl...@hotmail.com (Dave Klein)
Grupos: sci.chem
<snip>

My group here at Iowa State has run into some problems with the drying of
nitromethane by distillation. Hopefully someone can help us out....

A while back (>10 yrs) we had an explosion of the contents of a
nitromethane still. After refluxing on Calcium Hydride overnight, it was
noticed that a yellowish sludge was forming inside the flask. The
distillation was stopped, and the nitromethane was decanted from the
sludge. The flask was placed in the back of a hood, overnight, the flask
detonated and turned the flask into sand.


Recently, we used calcium chloride as the drying agent instead of calcium
hydride (300ml CH3NO2 over 2.5 g CaCl2). However, it was noticed that a
yellow sludge was again forming. Upon further reflux, the solution turned
maroon, then to black.


So my question is: Does anyone have any personal experience with this sort
of problem? and if so: How did you dispose of it?


Thanks For Your Time


Dave Klein



De: Uncle Al - ver perfil
Data: Sex 15 mar 2002 20:25
E-mail: Uncle Al <Uncle...@hate.spam.net>
Grupos: sci.chem
Ainda não classificadoClassificação:
mostrar opções

<snip>
-

Nitromethane is acidic and salts of the aci-nitro tautomer are
explosive. Try drying over activated 4A molecular sieves followed by
reduced pressure distillation.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!




As I said before in this thread, the Merck index says nitromethane forms explosive salts.

Therefore, I believe the extraction of nitromethane with an alkali is not a good idea.

[Edited on 13-4-2006 by Tacho]

neutrino - 13-4-2006 at 17:32

These salts are known as nitronates. Search this forum and RS (www.roguesci.org) for more information about them.

chemoleo - 13-4-2006 at 17:47

Yes, but the nitronates form under alkaline conditions. Doesn't look like alkaline conditions were employed here. I suggest that if you *must* use CaCl2, add some HCl to it to keep it acidic. Keep adding it during destillation. Although I seem to remember that NM is unstable both in alkaline and acidic conditions, but for the latter, I couldn't figure out why.
As I suggested before, possibly a route to purification is to form the nitronate first (witha base), purify this (clean in water), and react with dilute H2SO4 to form NM again, which should form an insoluble layer.
Nonetheless, distillation should be safe if no extreme temperatures, or base/acid additions are used. There's a prep on orgsyn for this, dealing with the destillation.

woelen - 13-4-2006 at 22:59

Nitronate is not stable in the presence of water, so this route does not work. If you want to make nitronate salts from nitromethane, then you need a strong base in non-aqueous solvent (e.g. CH3CH2ONa in CH3CH2OH). Even NaOH in CH3CH2OH is not suitable. The water formed in the reaction then slowly destroys your nitronate salt.

I don't know what the precise decomposition products are of nitronate/water. The material first becomes brown and then a dark, almost black, insoluble crap is produced. This crap still contains quite some nitro-groups, it can be made to decompose violently, but it surely is not useful for any other purpose than for making a bang.

xwinorb - 14-4-2006 at 14:40

I have just run a small experiment :

I added a small ammount of CaCl2 to distilled water, measured the pH with my electronic pH meter ( it is a good meter and I trust it ), I am getting right now 10.38

Looks like I might have formed nitronates whithout knowing it ( ? )


Question :

I have combined all the nitro I have after the described distillation. It is slighly yellow. Would it be safe to wash with diluted HCl and see if that removes the yellow color ?

Would this be safe to distill at RT ?


Further comments :

Also, I have once ( before this try ) distilled the pure RC fuel, I have the impression the yellow spots did not showed up, but I am not sure about it.

If that is really the case, I might end up dumping this one and distilling the RC again whithout drying this time. I am also trying to find 99 % nitro.

I am putting this on hold for now, maybe in one week or two. As I have said before, I might through away the yellow tinted one I got right now.

Problem seen at re-distillation

xwinorb - 18-4-2006 at 18:06

SWIX decided to try to re-distill the nitromethane, after testing a small ammount on a test tube.

Distillation initially OK, I started collecting at 90 C, because again looked like there was still some DCM mixed in. After a while, started noticing small bubbles forming at side of boiling flask, on localized spots. It started showing up more and more. Finnaly, small solid yellow spots started appearing at the previous bubble locations. Then I decided I was not liking it and stopped the distillation.

It is possible I could have finished it whithout problem, have done it before, but I did not know about nitronates at that time.

The distiiled fraction ( got some 70 g ) looks clear like water. After a while, staying in fridge, it is turning cloudy ( not yellowish like the input, though ). I think it still has some DCM and / or water mixed in. Probably it will clear and water will float to the top, have seen it before.

After turning off the heat, the yellow solids re-dissolved in the initial nitromethane fraction.

Any way I can test this to see if it is really nitronate ? Will it burn easier ? I tried to wash first fraction ( from previous distillation ) with HCl, it is still yellow.

Whatever this is, it is separable by distillation, most of it stays in the input fraction, but I believe part of it was carried over to distilled fraction.

If someone knows more about this please post. It seems to correlate with drying with CaCl2, I got more of the impurity this time, as described in first post. I have dried it more, and also combined with the DCM extraction ( bad idea ).

The RC fuel I used is PowerMaster, 50 %. I think it has castor oil and synthetic oil also.

I guess I will go back to distilling the RC fuel without drying or washing.

xwinorb - 18-4-2006 at 18:16

Would like to add this :

I tried to burn the two samples, after dripping in a piece of paper towel. The yellow one burned faster and more energetically.

The re-distilled nitro burned slower, easier to put down flame.

Punk - 18-4-2006 at 23:36

I know a fellow that used 80% nitro boat fuel as is in a mdma reductive amination synth and ended up with decent yeilds.

mootavic - 4-2-2012 at 22:02

I am surprised that nobody here has bothered to check the Material Safety Data Sheet on CH3NO2 to find out the answers to a lot of the questions here...

http://www.mallchem.com/msds/englishhtml/N5740.htm

nitromethane is in fact impact sensitive and is made more impact sensitive by contact with certain other compounds/elements. for example, if aluminium particles are mixed into CH3NO2 it becomes much more impact sensitive, to the point that in racing engines, it can cause preignition by the shock of the surrounding cylinder combustion events.

it is strongly advised NOT to distill nitromethane. it is an unnecessary process. Just call your local Drag Racing strip and ask where you can buy it from in 100%. Also, the ratio of cost per cc is strongly in the favour of just buying it outright not to mention not having to expose yourself to uneccesary risk.

Also it is not classed as an explosive [unless combined with sensitizers] and as the MSDS states,

UN1261
Hazard Class 3 [Flammable Liquid]

GreenD - 6-2-2012 at 07:18

a quick google search brought me to 100% nitromethane .

hames - 14-2-2012 at 04:44

yeah I just bought 4ltrs of 99.99% for $70 in Australia of all places from a hobby shop.

luckybot - 15-2-2013 at 21:12

Would the base extraction method also be applicable to recovering the methanol? So I'm thinking...

1. Add saturated NaOH solution to 92:8 MeOH nitromethane mixture
(Would an excess of base solution hurt anything?)
2. Put in freezer for a while
3. Vacuum filter off the nitro precipitate
4. Flush remaining MeOH with equal volume of water
5. Distill off and collect MeOH

Any obvious flaws in that my chem illiterate self is unaware of? Thanks.

Scr0t - 16-2-2013 at 01:52

Use more water with the NaOH, about 1/4 of the volume of the MeOH/MeNO2.
Pre-chil the MeOH/MeNO2 in the freezer first as it will get very hot and let it stand until it all cools down, filter and distill.
It would need an additional distillation as there is some ammonia/amine formed contaminating the distillate.

luckybot - 16-2-2013 at 10:51

When you say use more water do you mean a less saturated NaOH solution? Also, forgot to mention everything should be pre-chilled, good idea. I'm guessing multiple distillations won't be needed if it is distilled fractionally after the nitro has been filtered off?

[Edited on 17-2-2013 by luckybot]

Scr0t - 16-2-2013 at 12:58

Yes, I say less saturated partly due to perhaps an irrational fear of distilling salts of potentially explosive compounds and wanting to keep the solids dissolved. It also helps moderate the exothermic reaction due to the high specific heat capacity of water.

Excess of NaOH is no problem.

the amine contaminant is produced during the distillation and so can only be removed on the 2nd distillation.

When/if I next travel in this direction I would attempt identification of this amine but since you're heading down here maybe you can take the fore-run of the 2nd distillation and neutralize with HCl, evaporate to dryness and characterize the residue e.g. MP or other physical properties.

SM2 - 16-2-2013 at 15:03

you klotz's, why not pick up a gallon of the pure?

luckybot - 16-2-2013 at 15:30

Well if I can get it out of the same OTC mix I got my nitromethane for no extra cost with only a little fuss I would imagine it's worth it. Not to mention I haven't yet sourced a supplier of methanol.

[Edited on 16-2-2013 by luckybot]

luckybot - 17-2-2013 at 07:33

Okay I took a liter of the chilled 92:8 MeOH nitromethane mixture and added more than an equal volume of near saturated NaOH solution. I made the NaOH solution by dropping lye into water with stirring until it stopped dissolving and made a cloudy white mixture, after that I added some more water to bring it back to being clear. The MeOH/NaOH/Nitromethane proceeded to warm up slightly and first turn a pale yellow, then as it cooled towards room temp it turned a very dark brown/black, like used motor oil or dark cola. I put it in the freezer overnight and the next morning it was in the same state. I'm guessing I have screwed up somehow? I can see no precipitate since the mixture is so dark. Perhaps there is not enough water and things are staying dissolved in the methanol, the mixture did not freeze.

Filtering does nothing. I was imagining I would see a precipitate in my mostly still clear methanol, filter that and then re distill, this is looking much messier than I thought.

[Edited on 17-2-2013 by luckybot]

Scr0t - 17-2-2013 at 13:12

Turning black is normal.
But you used a lot more water than I did so nothing precipitated, you can proceed with the 1st distillation.

luckybot - 17-2-2013 at 13:28

So the filtering isn't even necessary? I guess the dissolved nitro stuff is going to stay behind in the distillation flask?

Scr0t - 17-2-2013 at 13:31

Yes, if you use a lot of water but I like to keep the volume down due limited flask sizes.
You should distill this preferably with a fractionating column and a black, maybe somewhat viscous mess will be left behind but poses no cleaning problems.

luckybot - 18-2-2013 at 18:01

Okay got a clear distillate coming over. Density checks out as methanol. I will go ahead and redistill like you said scr0t. My copper wire that holds up my column packing also made some pretty blue copper hydroxide, lol. Thanks for the help.