Sciencemadness Discussion Board

Synthesis/acquisition of alpha-methylstyrene

turd - 22-12-2013 at 14:55

It's a sad day for sciencemadness when destructive behavior of bullies is not only tolerated, but even rewarded, by closing threads those bullies do not agree with for some reason. Case in point:
https://www.sciencemadness.org/whisper/viewthread.php?tid=28...
https://www.sciencemadness.org/whisper/viewthread.php?tid=28...
Alpha-methylstyrene is an interesting chemical and its synthesis in a home setting is interesting as well as challenging. It perhaps can be turned into 1-phenylpropan-2-one and ultimately into (N-methyl)amphetamine, but that is perfectly fine under the forum rules and in any case the transformation is so impractical that I can only conclude that the bullies never performed an actual multi-step synthesis. The bullies are neither chemists nor scientists, lest they would see at first the challenge and an interesting compound. Instead their first reaction is one of segregation, whereas at the heart of real science there lies cooperation. Thus I find the closing of these threads unacceptable so I open this one to discuss the acquisition/synthesis of alpha-methylstyrene for those with interest in chemistry.

So in my humble opinion the two most practical and realistic ways of acquiring reasonable amounts of alpha-methylstyrene are:

1) Just buying it. This is an industrial chemical which I would suppose is absolutely unwatched (caveat emptor). Obviously it comes stabilized and partly polymerized, so it should be kept in the freezer and distilled before use.

2) Depolymerizing polyalpha-methylstyrene (idea of SM2) and used directly. Sounds like a nice project.

For the synthesis of smaller amounts the idea of Blarg! seems to be the best one: bromination of cumene followed by elimination. The bromination in itself is interesting since it is a textbook example of the regioselectivity of radical bromination: heat/radiation->side-chain. An example is given in JACS 77, 4025 (1955): up to 90% yield (based on Br2). Probably harder than it looks at first and where do you get 150W light-bulbs nowadays. ;)

Still doable in a home setting but even more difficult would be an elimination reaction of the alcohol analogue (cumyl alcohol, 2-phenyl-2-propanol). The latter can for example (I guess) be made by Grignard reaction of PhMgBr with acetone or MeMgI with acetophenone.

Pd catalyzed coupling reactions (idea of Blarg!) are IMHO simply too wasteful for such an industrial chemical.

Too hard for a standard lab are probably various variations of the cumene process (though some people here seem to be doing this kind of things). There are many patents but... ugh.

Other ideas welcome, haters not welcome. :D

bfesser - 22-12-2013 at 15:04

turd, you beat me to it! I was planning on re-creating the topic after seeing the first two get derailed. Thanks for saving me the effort. :)

Crowfjord - 22-12-2013 at 15:13

Glad you brought back this topic, Turd. I was considering doing so myself. Elimination of water from cumyl alcohol (I just now learned this name) was an idea I had previously. One can also make the tertiary alcohol by doing a Grignard on methyl or ethyl benzoate with methyl magnesium halide.

Why would the elimination be difficult? I was under the impression that secondary and tertiary benzyl alcohols were particularly easy to eliminate, to the point that it happens sometimes even accidentally.

DJF90 - 22-12-2013 at 15:50

When I first saw this, I searched OrgSyn as I figured something might have been said. I found this similar entry, which I'm sure could be applied using methylmagnesium bromide and a benzoate ester.

http://www.orgsyn.org/Content/pdfs/procedures/cv1p0226.pdf

S.C. Wack - 22-12-2013 at 18:39

Quote: Originally posted by turd  
It's a sad day for sciencemadness when destructive behavior of bullies is not only tolerated, but even rewarded, by closing threads those bullies do not agree with for some reason. Case in point:
https://www.sciencemadness.org/whisper/viewthread.php?tid=28...
https://www.sciencemadness.org/whisper/viewthread.php?tid=28...
Alpha-methylstyrene is an interesting chemical and its synthesis in a home setting is interesting as well as challenging. It perhaps can be turned into 1-phenylpropan-2-one and ultimately into (N-methyl)amphetamine, but that is perfectly fine under the forum rules and in any case the transformation is so impractical that I can only conclude that the bullies never performed an actual multi-step synthesis. The bullies are neither chemists nor scientists, lest they would see at first the challenge and an interesting compound. Instead their first reaction is one of segregation, whereas at the heart of real science there lies cooperation...haters not welcome. :D


You don't want people talking about things you bring up at the very start eh. Start a fresh, friendly thread by talking shit. Perhaps you paint with as broad a brush as anyone. Truth is ugly sometimes and threads need not be minty-fresh IMHO. Lettuce bee about truth and not misrepresent anything...and not lose sight that the threads in question were from someone whose sole, very strong interest in this forum so far is starting threads on where to buy chemicals, specifically from Sigma-Aldrich, borohydride, and now this. There shouldn't be anything wrong with pointing out things. Or asking what things are needed for, since many threads here have people barking up the wrong tree.

Impractical? Not for very amateur P2P, if you have the alkene...for the Pb tetraacetate the oxide can (easily and for many reasons) be made starting from a used car battery, weights, or somewhere else or be bought, then there's GAA, solvent in the procedure below, and the styrene. Oh and a distillation apparatus. Steam maybe.

alpha-Methylstyrene (1.2 g.) in acetic acid (6.5 mL) was added to a stirred suspension of lead tetra-acetate (5 g.) in acetic acid (6.5 mL) at 60°. After 30 min. the solution was poured into water and the ether extract was washed with sodium carbonate solution and with water and was dried (MgSO4). Evaporation of the solvent left a pale yellow oil (1.4 g.)

Which is 40% P2P, and 20% P2P diacetate. Increasing the time to 18 hrs gave 46% P2P and 1% diacetate. How about just bromine, sulfuric acid and benzene?

118g alpha-Methylstyrene was added to a mixture of 160g of bromine and 1200ml 15% H2SO4, and the mixture was heated at 80°C for 8h. The mixture was cooled to room temperature and the organic layer separated, and the aqueous layer extracted with benzene. The extracts and organic layer was mixed and dried over Na2SO4. The benzene was evaporated under vacuo, and the residue was vacuum distilled, and the fraction boiling at 75-85°C/8mmHg weighed 75g and was purified via its bisulfite adduct to give a product mixture boiling at 78-81°C/4 mmHg in 57% yield, consisting of 48.5% 2-phenylpropanal and 51.5% phenyl-2-propanone.

It would seem that there wasn't anything more to say originally about practical very amateur alpha-methylstyrene syntheses, so it's not like we've been withholding anything. (BTW SPISSHAK refers to this page.) The acetophenone/MeMgI->title cpd is in Weygand/Hilgetag.

Methylmagnesium iodide (2 moles) and acetophenone (1 mole) are brought into reaction in the usual way, the ether is distilled off, and the residue is heated for 6 h at 100°. Decomposition with ice-water, extraction with ether, drying, and distillation then afford the unsaturated hydrocarbon, b.p. 162° (5-6 g from each 10 g of acetophenone).

[Edited on 23-12-2013 by S.C. Wack]

Mr_Magnesium - 22-12-2013 at 20:32

I am not sure if you would like to actually order a-methylstyrene after reading what S.C Wack has said. Looked into it a bit more and i think its watched if you bought it pure. I'm not too sure but you could give it a shot.

Also how about the oxidation of cumene to cumyl hydroperoxide and dimethylphenyl carbinol.

Cumyl hydroperoxide on decomposition yields a-methylstyrene and acetophenone. However i think this is low yielding as these aren't major by-products. Also from what i have read it seems like it can be explosive but i am not too sure.

Dimethylphenyl carbinol can be dehydrated to form a-methylstyrene.

Also cymene could be a possibility?

Just throwing ideas out



[Edited on 23-12-2013 by Mr_Magnesium]

[Edited on 23-12-2013 by Mr_Magnesium]

Mesa - 22-12-2013 at 23:48

I did a quick google search for a-methylstyrene after reading this thread and found the first 5 pages were entirely made up of the spambot pages for sites like alibaba/chembook/etc.

That was pretty surprising. I've done the same thing with hundreds of other chemicals, some fairly obscure, but this is the first time I've seen 100+ links with no legitimate hits...

I kinda got a bit obsessive after that. It is now 3 hours later and I can confidently say that I know far too much about possibly the most useless polymer feedstock known to man.
In the event that you do manage to find it, the vast majority of published studies I've found is relating to thermal decomposition/hydrocracking/other possible depolymerizations, it'd be pie from there :P.

Regardless, I highly doubt either the monomer or polymer are watched or in any way considered suspicious. I'd comfortably order 20kg+ amounts from overseas if I felt like it(or could afford it;))


Edit: Oops, the only reason I took more than a passing interest in this thread was to comment on the OP, which I promptly forgot to do. To preface, while I realise its not relevant to the title of the thread, It'd bug me relentlessly if I let it be. I mean, I gotta make some sort of purely opinionated message to avoid realising how useless the last few hours have been(kidding).

Anyways... Whilst I agree with the sentiment turd, as well as the 'bully' being out of line with his reply, I do think he was pretty much spot on with the profiling of blarg! Almost every post made by that member has had some indirect relation to the more popular synthetic pathways to illicit drugs.

Added to that, the vast majority of his posts/threads scream "spoonfeed me and write the recipe before you leave!" without any attempts to find existing threads with essentially identical questions. But instead, creates a new one that consists of a single sentence.

As I said, I agree with your sentiment, but is this really the sort of guy you want to be championing?




[Edited on 23-12-2013 by Mesa]

turd - 23-12-2013 at 01:48

Quote: Originally posted by turd  
1) Just buying it. This is an industrial chemical which I would suppose is absolutely unwatched (caveat emptor). Obviously it comes stabilized and partly polymerized, so it should be kept in the freezer and distilled before use.

2) Depolymerizing polyalpha-methylstyrene (idea of SM2) and used directly. Sounds like a nice project.

Of course, with a Tc of 66°C (https://en.wikipedia.org/wiki/Ceiling_temperature) those two things are pretty much the same. Truly a fascinating compound.
Quote: Originally posted by Crowfjord  
Why would the elimination be difficult?

I was unclear, not the elimination seemed diffucult to me, but the oxidation cumene->cumyl alcohol.
Quote: Originally posted by S.C. Wack  
Impractical? Not for very amateur P2P

Thank you for the nice review. Unfortunately I know this page (https://www.erowid.org/archive/rhodium/chemistry/phenylaceto...) by heart, so no news for me. And as someone who actually once made P2P, I stand by my verdict: highly impractical. And so what - if this is the goal of Blarg! and he synthesizes alpha-methylstyrene on the way: all the better. I'd like to know how he fared. Not that I expect him to report back after this welcome.
Quote: Originally posted by Mr_Magnesium  
Also how about the oxidation of cumene to cumyl hydroperoxide and dimethylphenyl carbinol.

Yes, but all references I found were some kind of industrial process. :(

Thank you for the interesting discussion so far - also you, S. C. Wack, though your tone was needlessly aggressive.

[Edited on 23-12-2013 by turd]

Nicodem - 23-12-2013 at 03:25

Quote: Originally posted by turd  
I was unclear, not the elimination seemed diffucult to me, but the oxidation cumene->cumyl alcohol.

There are methods in the literature, either using DMDO, or oxygen followed by the initially formed cumyl peroxide reduction (can be done directly in the presence of alkali hydroxides). I currently don't have the time to review the literature (again), but anyone interested can do that easily. Probably a more simple approach is benzylic chlorination with TCCA followed by elimination with ethanolic NaOH. TCCA is easily available and more manageable than chlorine or bromine. The benzylic chlorination of toluene with TCCA is already described on this forum (as well as in the literature). Developing a preparative method for cumene is a matter of a couple of experiments. The elimination step is surely already described in the literature.

PS: Interesting thing about that low ceiling temperature of poly(alpha-methylstyrene). I never thought that some polymers could depolymerize so easily.

Mr_Magnesium - 23-12-2013 at 03:42

Quote: Originally posted by Mr_Magnesium  
Also how about the oxidation of cumene to cumyl hydroperoxide and dimethylphenyl carbinol.[/rquote]
Yes, but all references I found were some kind of industrial process. :(

Thank you for the interesting discussion so far - also you, S. C. Wack, though your tone was needlessly aggressive.

[Edited on 23-12-2013 by turd]


Copper/magnesium oxide catalyzed oxidation of cumene. I am not too sure if this yields a-methylstyrene, in the paper it is mainly focusing on cumyl hydroperoxide.

Xu, SA ; Huang, CP ; Zhang, J ; Chen, BH
Korean Journal Of Chemical Engineering, 2009, Vol.26(6), pp.1568-1573

However decomposition of CHP yields an EXTREMELY LOW amount of a-methylstyrene. Paper i am currently reading says its 0.02% hahah :o

So you can get rid of that route.

Cumyl alcohol can be dehydrated to alpha methyl styrene which looks a lot more promising.




[Edited on 23-12-2013 by Mr_Magnesium]