Melgar
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Phenylethanolamine from styrene
Styrene could be reacted with TCCA in aqueous acetone to yield the chlorohydrin:
http://www.uff.br/sbqrio/download/spotilight/132.pdf
The chlorohydrin could then be reacted with an excess of alcoholic ammonia to yield phenylethanolamine, via nucleophilic substitution:
http://www.chemguide.co.uk/mechanisms/nucsub/ammonia.html
It looks like a pretty straightforward set of reactions. Any reason it wouldn't work?
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Polverone
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The magic 8-ball that is searching Google Books and looking at that revealed by "snippet view" indicates this should work. There is at least one book
that mentions reacting styrene chlorohydrin with ammonia or alkylamines. Several others mention using styrene and substituted styrene epoxides, which
I think should behave similarly here. I don't know if poly-alkylation will be sterically inhibited or if you need a large excess of ammonia as you
would with simple ethylene chlorohydrin. Ammonia is cheap, probably safer to try large excess at least to start. Let us know how this goes!
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smuv
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It will definitly work, the question is which isomer will you get. For styrene you will get very predominantly 2-phenyl ethanolamine however for
propenylbenzenes the product distribution starts getting muddy.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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jon
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has any one of you worked with styrene monomer personally?
reason i asked, i wanted to know how tempremental it is and what conditions to avoid since it's so highly reactive.
it's useful for so many things.
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smuv
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also...this is not simple SN2. Predominantly it is deprotonation/cyclization to the epoxide and then nucleophilic ring opening.
I believe nicodem spoke of making this exact compound from styrene. Maybe PM him if he doesn't stop by.
[Edited on 6-28-2011 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Polverone
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I've worked with styrene monomer. I ordered a gallon several years back from a fiberglass place. I still have most of it. I poured some of it into a
small glass bottle for easier handling -- bad idea. It had thickened to the consistency of cold maple syrup 6 months later. The stuff that I have in
the original plastic jug is still perfectly fluid. I'm not sure why the material in the jar started to polymerize. I thought if anything that glass
would reduce oxygen diffusion and slow polymerization. Maybe it was light exposure -- I used a clear jar rather than amber glass.
I've also made a small quantity of (mostly) styrene starting from polystyrene packing peanuts. First I dissolved them in acetone and let the acetone
evaporate to get a higher-density solid. Then I dry distilled fragments of the plastic from a test tube using an open flame directly on the tube. I
obtained a clear, colorless, fluid distillate that smelled the same as my commercial monomer. It was oxidized all the way to benzoic acid with
alkaline potassium permanganate since I didn't have any special need for an extra mL of styrene monomer. Based on later reading I presume that my
"styrene monomer" prepared this way also contained lightweight styrene oligomers, benzene, ethylbenzene, etc. Anyone who needs pure styrene monomer
and starts from polystyrene is advised to search the archives here and prepare to put in more effort on characterization and purification than I did
those years ago. For many reactions benzene and alkylbenzenes aren't going to interfere anyway, so the primary goal is just fully disassembling the
polymer.
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jon
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thanks for that bit of wisdom.
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Nicodem
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Styrene chlorohydrin can react with ammonia trough the corresponding oxirane. The reaction of the oxirane with ammonia is known [1]. Heating styrene
oxide with 4-fold amount of NH3(aq) at 90-125 °C gives an 18% yield of 2-amino-1-phenylethanol (in the fraction having bp 146-196 °C at 16 mbar),
the rest apparently being dialkylation products (bp 186-235 °C at 5 mbar) and their cyclization product 2,6-diphenylmorpholine, which is probably
formed during the distillation.
When using styrene chlorohydrin, this must first cyclize to the oxirane, which gives one equivalent of ammonium chloride. The reaction mixture would
thus consist of an ammonia/ammonium buffer. This would somewhat inhibit the dialkylation by in situ amine protection by protonation (amines are about
10 times more basic than ammonia). I would estimate the yield could be thus improved to about 20-40%, particularly with an higher excess of ammonia
(use of a cosolvent could also help).
The authors compared the reaction of styrene oxide and its chlorohydrin with diethanolamine and found the oxide gives a better yield (89% vs. 63%),
but they used different and aqueous conditions for the chlorohydrin which requires the presence of a base. With ammonia you already have to use
aqueous conditions and its excess provides the basic conditions required for the cyclization to the oxirane.
UTFSE for more info on SN2 substitutions and why is it near to impossible to monoalkylate ammonia with 1°-alkylating reagents (this has been
explained a dozen times already!).
Obviously, such a synthesis of 2-amino-1-phenylethanol is crap, as there are better ways to do this from styrene oxide via the Delepine reaction.
Selectivity is a non-issue and yield quantitative [2].
[1] J. Am. Chem. Soc. 1945, 67, 516–518. DOI: 10.1021/ja01220a004
[2] Arch. Pharm. 1959, 292, 761.
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unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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Sedit
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I haven't fully read this thread yet so sorry if its been said but look around and you will find that epoxidation of Styrene will form
2-Amino-1-phenylethanol selectively thru Aminolysis in Ammonia hydroxide solution.
This appears to eliminate the issues that would arise from attempting to perform an SN2 on the halogen where if not enough Ammonia is present you will
yield a mixture of products.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Nicodem
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Read the post above yours.
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Sedit
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Sorry your absolutely right, I was in a rush when I wrote that but I was looking into this same synthesis a month or so ago just to find Styrene has
been pulled from the shelf around here so I could never attempt it. Just thought I would toss my 2 cents in while it was still on my mind.
Nicodem is correct, proceeding thru styrene oxide is the way to go. The patents I was reading suggested using concentrated Ammonia hydroxide solutions
but surely Hexamine would suffice as the ammonia source in the reaction and more then likely do away with a large amount of bulk to the reaction
mixture.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Melgar
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Huh, apparently you can use ammonium acetate as the ammonia source, and do this reaction neat in a microwave. Styrene oxide is just as easy to make
as styrene chlorohydrin, so that wouldn't change things much. Granted, the attached paper is an Indian one, but there's plenty of literature out
there supporting the idea that microwaves assist epoxide ammonolysis.
Attachment: ethylamine.pdf (56kB)
This file has been downloaded 983 times
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497
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N2O4 reacts with alkenes to form a mixture of products, but under the right conditions I believe it gives a good yield of a-nitro b-nitrite/nitrate.
And it is selective, the c-nitro will always be on the least substituted carbon. There's lots of literature out there on the N2O4+alkene reaction. I
think it proceeds at room temp too. The nitroester is rapidly hydrolyzed to the nitroalcohol. I'm sure you could find quite an easy method to reduce
the nitroalcohol to the aminoalcohol with a little searching. N2O4 is pretty simple to make by a number of ways, especially since this reaction could
utilize N2O4 diluted in other gasses, and the presence of O2. Dissolving Cu in HNO3, heating Cu(NO3)2, etc.. Adding some air to the nitrogen oxide gas
mixture will help your yield by oxidizing it more completely to N2O4, especially if made by dissolving metals. The only issue may be contamination
with phenylethylenediamine. It can't be that tough to separate.
[Edited on 1-7-2011 by 497]
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