Sciencemadness Discussion Board - Propylene (oxide) synthesis

Propylene (oxide) synthesis

497 - 2-8-2008 at 04:06

What is a practical OTC source of propylene? There are many options that I see, few look usable though. In the end I want propylene oxide, but I have everything else worked out except for a propylene source.

Isopropyl alcohol can be dehydrated to propylene. From what I have seen in patents it cannot be done as ethylene is synthesized from ethanol because of polymerization cause by the sulfuric acid. Is this true? Could it be done without too much trouble, even if the yield is not great? I have found few details. I have found details that say that a silica gel-alumina catalyst will very efficiently dehydrate alcohols including isopropyl. Unfortunately it is the high temp, high pressure gas phase type reaction that would be a major pain in the ass to set up.

Dehydrogenation of propane comes to mind. I have found plenty of info on it, but its all industrial scale with exotic catalysts and high pressures... maybe there's a way to do it small scale?

Pyrolyzing butane. The yield sucks and I have found few details, Butane is cheap, and as long as the separation from byproducts is not too hard, it might be usable?

Possibly dehydration of propylene glycol? With certain catalysts it is said to give propylene oxide. Since propylene oxide is actually my end goal that would be great. Unfortunately selectivity seems to be low and give mostly propionaldehyde and acetone. I need to look into it more.

I looked into pyrolyzing polypropylene, but alas it just gives a bunch of complex branched hydrocarbons and little if any propylene...

Any ideas or comments?

not_important - 2-8-2008 at 04:20

The vapour phase dehydration of isopropanol over Al2O3 does not require high pressure, and temperatures are in the 200 to 300 C range.

497 - 2-8-2008 at 04:29

Hmm yes that may be the best option. Yeild will probably be worse with low pressure but that doesn't matter much considering the price of isopropyl. I would still like to avoid vapor phase reactions if i can, but it may be my only option..

Also I wondering about butanol, would it work the same? I don't see why not.

[Edited on 2-8-2008 by 497]

DJF90 - 2-8-2008 at 04:34

Heating (and refluxing) with conc. sulphuric or phosphoric acid is also standard procedure. Just remember the product is in the gas phase...

[Edited on 2-8-2008 by DJF90]

Polverone - 2-8-2008 at 10:17

You can convert hot propylene glycol to chlorohydrin with HCl gas then react the chlorohydrin with base to form propylene oxide. In some places propylene gas is available in cylinders as a torch fuel. In some places propylene oxide itself is available as a go-kart fuel additive. See this thread.

Formatik - 2-8-2008 at 10:51

Propylene: 200g isopropanol are let sit for 24 hours with 650 g melted ZnCl2, and then are heated (Friedel, Silva, Jahresberichte, 1873, 322). Drip eventually 4 pts propyl alcohol onto 3 pts P2O5 (Beilstein, Wiegand, Ber. 15, 1498). From allyl bromide or 1-bromopropylethyl ether by addition of Zn dust in 95% pure ethanol (Ber. 31, 3071), etc. According to an older reference I’ve found, propylene also forms by heating isopropanol with an excess of conc. H2SO4, just like by ethylene with ethanol (Graham-otto's ausführliches Lehrbuch der Chemie by Julius Otto, Thomas Graham, pg. 324). For propylene oxide, there is also a way of obtaining it directly from propylene and H2O2 and catalysts, e.g. USP5599955.

497 - 2-8-2008 at 13:08

I like that idea Polverone, it just requires bubbling HCl through hot propylene glycol? Do you know anything more about it like yield, time, temp, etc?

My current plan goes something like this:

Figure out source of propylene (main problem)
Extract HOCl from solution with MEK or acetone
React HOCl with propylene in the ketone (does it need water?) to form the chlorohydrin
Distill off ketone
React with a base to form propylene oxide.

If Polverone's method is practical, it will simplify things greatly. If it doesn't work out then I'll have to try the old sulfuric acid dehydration... And if that doesn't work I'll have to try a gas phase dehydration over a catalyst. What about other more powerful water absorbers like B2O3 or HPO3? Maybe they'd work better?

kclo4 - 2-8-2008 at 13:20

Quote:

Extract HOCl from solution with MEK or acetone

Whaaa???

http://en.wikipedia.org/wiki/HOCl

Polverone - 2-8-2008 at 13:40

Quote:

Originally posted by 497
I like that idea Polverone, it just requires bubbling HCl through hot propylene glycol? Do you know anything more about it like yield, time, temp, etc?

I'd suggest spending a couple of hours on Google Books, keeping in mind that there's not really a consistent nomenclature for the materials you're interested in. IIRC I found numerous references, some quite detailed, to forming ethylene chlorohydrin from the boiling glycol using HCl gas. There were a number that indicated propylene glycol would work similarly.

I read quite a bit on Google Books about these reactions some months ago but I don't recall the specifics. There should be plenty of information in books found on Google Books and archive.org though.

ScienceSquirrel - 2-8-2008 at 15:46

Reaction of propylene-1,2-glycol with a suitable reagent should result in the formation of 2-chloropropan-1-ol in high yield.
Reaction with a suitable base should form propylene oxide.
After that reaction with benzene and a catalyst to yield 1-phenylpropan-2-ol should be a breeze

497 - 2-8-2008 at 18:03

Thanks Polverone, I will do that.
A good patent on continuous vapor phase alchohol dehydration is US Patent 2377026. The catalyst looks quite easy to make too.

Quote:

Whaaa???

Look up US Patent 3578400. It looks pretty useful for any reaction that needs pure HOCl. I was surprised at first too.

kilowatt - 2-8-2008 at 18:34

You can buy cylinders of propylene from welding suppliers. Around here it is sold as "HPG" gas. It's about $90 for 27lbs.

turd - 2-8-2008 at 22:26

Quote:

Originally posted by ScienceSquirrel
After that reaction with benzene and a catalyst to yield 1-phenylpropan-2-ol should be a breeze

Regioselectivity?

S.C. Wack - 2-8-2008 at 23:42

Looks pretty high. Maybe someone has Springer access.
http://dx.doi.org/10.1134/S1070427206030141

Bromobenzene Grignard reagent likewise gives 1-phenyl-2-propanol as the only alcohol, and in the same chiral purity as the epoxide.

Here be the paper...

sparkgap - 3-8-2008 at 04:29

...that Mr. Wack was referring to.

sparky (~_~)

Attachment: syntharalk.pdf (56kB)
This file has been downloaded 1753 times

Nicodem - 4-8-2008 at 05:27

Regarding propylene glycol to propylene chlorohydrin, I will cite myself:

Quote:

Originally posted by Nicodem
It seams it might be possible to make 1-chloropropan-2-ol by bubbling HCl trough 1,2-propanediol at about 110°C. At least by analogy with glycerol as described at Org. Synth. Glycerol can actually even be dichlorinated up to 1,3-dichloropropan-2-ol. There is no reason why this would not work with 1,2-propandiol as well under the same conditions.

1-chloropropan-2-ol is an interesting compound that can be used to prepare a useful reagent, propene oxide.

From http://sciencemadness.org/talk/viewthread.php?tid=6455

497 - 4-8-2008 at 14:17

Thank you, I looked for the procedure on google books and was unable to find any that were viewable.

Do you know if a small amount of water being present from not completely dry HCl or glycol would be a problem? And I don't have glacial acetic acid.. Maybe it would proceed without it?

497 - 16-8-2008 at 09:45

I wonder if it would be possible to produce the HCl in situ with NaHSO4 and NaCl(or any other suitable chloride)? They are probably slightly soluble, maybe enough to react, or a little water could be added. I don't believe either salt or the resulting Na2SO4 would react with the glycol or chlorohydrin, but I could be wrong. It would seem the produced HCl would have a very large amount of contact with the glycol, if all goes as I think it would.

I would really like to avoid the separate HCl generator if I can. If I am forced to use it, would NaHSO4/NaCl be able to produce dry enough HCl? Maybe dry it with a little CaCl2? Since I would need a pretty large quantity of HCl, I'd like to avoid having to use multiple gallons of concentrated H2SO4 and Hydrochloric acid any way I can...

vulture - 16-8-2008 at 14:06

Bubble your HCl gas through H2SO4 and it should be dry enough.

not_important - 16-8-2008 at 17:44

The Org. Synth. reference Nicodem includes

Quote:

An alternative procedure which is slower and gives slightly lower yields, but which does not require a hydrogen chloride generator...

using concentrated hydrochloric acid and acetic acid. The organic acid appears to be needed.

It should be noted, given that most preparations involve reflux, that the simple chlorohydrins are somewhat toxic; good ventilation and gloves would be wise.

http://www.cdc.gov/niosh/idlh/107073.html

octave - 16-8-2008 at 20:58

Could it be possible to depolymerize polypropylene(http://www.freepatentsonline.com/4624993.html) and then follow the first method suggested in (bad source I know) http://en.wikipedia.org/wiki/Propylene_oxide ? If it would work,which I doubt, then it would be rather easy and cheap as all chemicals required are very readily available.

[Edited on 17-8-2008 by octave]

not_important - 16-8-2008 at 23:19

The poly-olefins tend to give larger hydrocarbons than the original olefins; you get a gasoline or diesel like mixture with little C3 hydrocarbon.

497 - 17-8-2008 at 13:41

I read a paper about the decomposition products of PP a while ago. It resulted a soup of maybe 30 different hydrocarbons, none of which made up a very large fraction of the whole (some 0.1% others 10%). I don't think propylene was even on the list.

I like the alternative procedure except that it requires refluxing a very corrosive mixture. Since I don't have a glass condenser, this might be hard to rig up. I suppose I'll figure something out.

Since I really don't like the idea of a vacuum fractional distillation of the resulting product I'm thinking I'll just distill at standard pressure until most of the HCl is gone and then add Ca(OH)2 to make propylene oxide which will hopefully be easy to distill out. Will this work even with the glycol still present?

The whole thing will definately be done outside.

MagicJigPipe - 17-8-2008 at 19:56

I'm sorry if this has been mentioned as I don't have time to read the entire thread at this point in time...

Propylene (most likely impure, but hey, when has that stopped us before?) can be purchased at just about any welding supply shop by the cylinder. It's more expensive now (for obvious reasons) but still, it's not too bad. Apparently even some hardware stores sell small cylinders of propene.

What I would do is buy it and focus more of my efforts on cleaning it up. Imagine how much easier it would be to have propene "on tap" as opposed to relying on a reaction.

EDIT
Also, propylene oxide can be purchased online. It is EXTREMELY rare and there's only one place that I know of that still has it. U2U me if you want the source as I don't want to possibly make it go bye bye by posting it publicly.

[Edited on 8-17-2008 by MagicJigPipe]

HCl from bisulfates

Formatik - 17-8-2008 at 20:24

Molten KHSO4 (Mp. 210ºC) reacts with KCl under formation of HCl (E. Mitscherlich, Pogg. Ann. 18 [1830] 152). Tried it with NaHSO4 and NaCl (together melted gave fog with NH3, where NaHSO4 melted alone did not), both bisulfates are also hygroscopic so could have some water content already.

497 - 18-8-2008 at 09:49

@ MJP Yes someone already said propylene was available at welding stores. I have taken that into consideration, if I do end up needing a propylene source. Currently I'm planning on doing from propylene glycol to propylene chlorohydrin, no propylene involved. If that doesn't work out then I may have to try to find some propylene at the hardware store.

Unless the online source is very cheap, I don't think its much use to me. I will need multiple kilograms of the stuff...

@ Shockwave Thanks for that information, I will probably use that method. Apparently NaHSO4 will melt at ~58*C when monohydrate, while anhydrous melts above 300*C with decompositon. When did yours melt?

[Edited on 18-8-2008 by 497]

ScienceSquirrel - 18-8-2008 at 09:57

Quote:

Originally posted by 497

Unless the online source is very cheap, I don't think its much use to me. I will need multiple kilograms of the stuff...

Propylene oxide is quite volatile and surprisingly toxic.

Making this stuff safely on a kilogram scale is going to require some serious kit.

497 - 18-8-2008 at 10:51

Yes I know its nasty stuff... 200 ppm for 8 hours begins to be toxic IIRC. I'm also considering 1,2 Butylene oxide for that very reason. 500 ppm for 8 hours is safe and it is much less volatile. Unfortunately butylene and butylene glycol are not very easy to get in quantity as far as I know. In case you didn't figure it out already, my main interest in these compounds is for FAEs. Gram for gram they are pretty well equivalent to TNT in explosive power.

Formatik - 18-8-2008 at 11:22

Quote:

Originally posted by 497 @ Shockwave Thanks for that information, I will probably use that method. Apparently NaHSO4 will melt at ~58*C when monohydrate, while anhydrous melts above 300*C with decompositon. When did yours melt?

I used a low flame from a lit match to melt both the bisulfate and mixture, but didn't take a temperature measurement.

ScienceSquirrel - 18-8-2008 at 17:32

Quote:

Originally posted by 497
Yes I know its nasty stuff... 200 ppm for 8 hours begins to be toxic IIRC. I'm also considering 1,2 Butylene oxide for that very reason. 500 ppm for 8 hours is safe and it is much less volatile. Unfortunately butylene and butylene glycol are not very easy to get in quantity as far as I know. In case you didn't figure it out already, my main interest in these compounds is for FAEs. Gram for gram they are pretty well equivalent to TNT in explosive power.

You are proposing making propylene oxide, which is quite toxic, on a kilogram scale and then using it to build a fuel air weapon?

That is highly likely to result in the death of yourself, friends or neighbours or a run in with the local anti terrorist squad.

I have all my nails and other male squirrel 'bits'! I intend hanging on to them, you may not be so lucky

Why you want to do that?

meme - 18-8-2008 at 21:42

I had some practical OTC advice about propylene oxide itself, but after the last few comments as a weapon, I can't help unless I am convinced you have some legal reason to want it.

Energetics are cool, weapons are for weenies.

497 - 18-8-2008 at 23:12

@ Squirrel
What are you talking about? Toxic compared to what? All the MSDS reccomends is safety glasses, gloves, and good ventiliation. I'm not some kewl doing this in my basement. According to MSDS:

ORL-RAT LD50 380 mg kg-1
IHL-MUS LC50 1740 ppm/4h.
IPR-RAT LD50 150 mg kg-1
IHL-DOG LCLO 2005 ppm/4h
ORL-GPG LD50 6600 mg kg-1
IPR-RAT LD50 364 mg kg-1
SKN-RBT LD50 1500 mg kg-1

Propylene oxide in itself is not remotely explosive, only mixed the the perfect proportion of air and hit with a powerful initiation blast at the exact right time (about 60 milliseconds after dispersal) will it detonate. In my view this makes it much safer that any explosive (not considering toxicity of course). And why the hell do you think I would try anything like that near any inhabited area??? Come on now, I'm not that stupid. A friend of mine initiated several hundred pounds of AN not too far away from town and had no problems nor runins with the law, I'm not too worried about a couple pounds of propylene oxide detonated miles from anyone. Seriously, give me a little credit here, I'm not some kid thats bored and wants to make a loud bang.

@ meme
Weapon? Why is it any different than any other energetic material? I have no intention of using it to hurt or damage anything. or any one. I am mostly interested in it because it is novel and as far as I know never been attempted by an amateur. If for no other reason, give your wisdom so that others who are not using its energetic properties may benefit. As I understand it, it is a handy chemical precourser for quite a few things.

[Edited on 18-8-2008 by 497]

k

meme - 18-8-2008 at 23:36

It is a commen funigant. While I don't think that most companies would sell it to you just as an individual, a license for fumigation is like $35 here IIRC. Also, social engineering is an artform we all should possess.

Also, it is still used as a racing fuel, and racers would have it even if the NHRA banned it.

And, apparently, it is used to pateurize raw almonds (?!) which I just learned while verifying my aging mind ;P

I just want to point out what a beautiful addition to substitutued phenyl-and indole-isopropylamine chemistry it can be.

ScienceSquirrel - 19-8-2008 at 03:09

I really think that detonating a few hundred pounds of anything does fall outside of the remit of mad science.
Just reading the MSDS of a compound is a bad way to guage the hazards of a compound in my opinion.
Maybe we are moving into an era of tick box science.
Read the MSDS, that's the safety angle dealt with then.
Propylene oxide has not got a strong odour and it has a very low bp ( 34 C ) so you have to allow for that in assessing its risks.

497 - 19-8-2008 at 11:02

I wasn't involved in that, and I agree it is not really mad science. One of them (there were actually two blasts around that size) was used to demolish an old cabin that the owner wanted to get rid of. They weren't just for fun, they were experiments. Just a bit oversize...

You are right about the safety part, that is a big problem. But there are a few things that make me think it is not *too* hazardous. One, it is sold in 5 gallon containers to anyone. Two, it can be shipped UPS. Three, as far as I have seen MSDSs tend to overstate risks (they assume chronic exposure). Of course all this does not mean it is safe, I will still treat it with plenty of respect. Fortunately I have a bit of trick up my sleeve to deal with its very high volitality. Here in Alaska, it gets quite cold, -40*C is not uncommon for a few days, so I may simply wait until it gets cold out to do any handling of propylene oxide (or ethylene possibly). At -20 outside with a fan blowing away from me, I think things would be pretty safe. Anyone not in a cold climate could use dry ice to cool it effectively.

This shows how I will attempt it:

http://www.google.com/patents?id=k14qAAAAEBAJ&printsec=a...

Calculated distance to 1 psi overpressure: 30 meters.

[Edited on 19-8-2008 by 497]

ScienceSquirrel - 19-8-2008 at 15:22

Quote:

Originally posted by meme
I just want to point out what a beautiful addition to substitutued phenyl-and indole-isopropylamine chemistry it can be.

It does seem to be a versatile three carbon synthon that can yield 1-arylpropan-2-ols via electrophilic Friedel Crafts type reactions or addition of metallated nucleophiles. :cool:

ScienceSquirrel - 19-8-2008 at 17:48

Quote:

Originally posted by 497
I wasn't involved in that, and I agree it is not really mad science. One of them (there were actually two blasts around that size) was used to demolish an old cabin that the owner wanted to get rid of. They weren't just for fun, they were experiments. Just a bit oversize...

You are right about the safety part, that is a big problem. But there are a few things that make me think it is not *too* hazardous. One, it is sold in 5 gallon containers to anyone. Two, it can be shipped UPS. Three, as far as I have seen MSDSs tend to overstate risks (they assume chronic exposure). Of course all this does not mean it is safe, I will still treat it with plenty of respect. Fortunately I have a bit of trick up my sleeve to deal with its very high volitality. Here in Alaska, it gets quite cold, -40*C is not uncommon for a few days, so I may simply wait until it gets cold out to do any handling of propylene oxide (or ethylene possibly). At -20 outside with a fan blowing away from me, I think things would be pretty safe. Anyone not in a cold climate could use dry ice to cool it effectively.

This shows how I will attempt it:

http://www.google.com/patents?id=k14qAAAAEBAJ&printsec=a...

Calculated distance to 1 psi overpressure: 30 meters.

[Edited on 19-8-2008 by 497]

That is an idiot's firework.

If it did not detonate, what would you do?

Try and set it off from a distance or leave it to fester in the field?

497 - 19-8-2008 at 20:41

Until I knew it would work, I would not attempt a charge quite that big. If it failed to detonate it would most likely make a fireball, disposing of it well enough. I would add a bit of Al to the initiator charge to make sure it ignited if nothing else. If it didn't ignite at all I would have a secondary initiator that fired off a charge of black powder or CuO/Al thermite to ignite it.

You are being awfully negative. Fester in a field?? You make it sound like fucking mustard gas! It would evaporate and blow away very quickly if not ignited. It would most likely be done in an old gravel pit miles from any houses.

meme - 20-8-2008 at 00:12

Quote:

Originally posted by ScienceSquirrel

Quote:

Originally posted by meme
I just want to point out what a beautiful addition to substitutued phenyl-and indole-isopropylamine chemistry it can be.

It does seem to be a versatile three carbon synthon that can yield 1-arylpropan-2-ols via electrophilic Friedel Crafts type reactions or addition of metallated nucleophiles. :cool:

I really want to de-rail this thread . . .But thou must not push off-topic. *looks around for moderators*

Blowing up such a versatile tool is sad

. I'm going to be good though and try to think about explosions

497 - 20-8-2008 at 01:33

Its fine if you want to derail it. The thread was intended for anything involving propylene and/or propylene oxide. I think the mods probably would not mind the discussion of other aspects of propylene oxide chemistry in it. This is the organic chemistry forum after all. If it was only meant for FAEs I would have put it in the energetics section. FAEs just happen to be my personal interest in it, but this is not my personal forum

And don't be too sad about blowing it up, it is available online in 5 gallon jugs if you look hard enough. Think about all that H2SO4, HNO3, etc. that gets "blown up" when detonating conventional explosives.

[Edited on 20-8-2008 by 497]

ScienceSquirrel - 20-8-2008 at 03:26

I must admit having gone off explosives, homemade or otherwise, with advancing age.