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phendrol
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Oxidation of styrene to phenylacetaldehyde
I'm thinking about oxidizing styrene monomer to phenylacetaldehyde. I know styrene can be oxidized to the epoxide and then further to
phenylacetaldehyde. Styrene oxide can be prepared from styrene via a chlorohydrin. Nicodem posted a nice, OTC recipe with TCCA:
http://www.sciencemadness.org/talk/viewthread.php?tid=15284#...
The method is simple and fast. The chlorohydrin can be surely prepared using sodium hypochlorite as well. But how can I rearrange the epoxide to the
aldehyde? Is there any way to oxidize it further with TCCA or sodium hypochlorite? Can a one pot oxidation from styrene to the epoxide and then
further to the aldehyde be done?
In this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=7641
Nicodem wrote that he was able to do a one pot oxidation of styrene all the way to phenylacetic acid, using H2O2, H2SO4 and formic acid in water. Now
phenylacetic acid is not what I'm after, but if a reaction like that is possible, I'm sure it could be modified just a bit to stop at the aldehyde. I
was trying to find some info on this and the closest thing I found is the oxidation of isosafrole with peracids.
https://www.erowid.org/archive/rhodium/chemistry/peracid.htm...
So if I'll use styrene instead of isosafrole what can I expect? Is it possible to get phenylacetaldehyde this way? Or maybe it would go even further
with the oxidation and yield PAA?
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Methyl.Magic
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If you want to get the phenylacetaldehyde I dont know where is the problem of the peracid method. Styrene oxyde are not usually formed with peracid
because they are very prone to be opened an acidic environement because of the stabilised benzylic carbocation. But to form the phenylacetaldeyde you
MUST open the epoxide, so for me I don't see any problem here.
Another problem is the stability of the phenylacetaldehyde. it's not very stable. Moreover the commercial product is never sold as the pure form but
always in solution. Maybe it's very prone to overoxydation to phenylacetic acid by oxygen the same way as benzaldehyde. If the case it's possible you
cannot use strong oxydant such as peroxide especially with the presence of acid but check the stability of the compound first.
FSO3Me
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phendrol
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Well the peracid is advantaging because it can be a one pot synthesis and as soon as I'll get some formic acid I'll attempt it.
I want to follow one of the methods from rhodium archive (link in the first post) substituting styrene for isosafrole. It looks promising and the only
thing I worry about is that phenylacetaldehyde may be further oxidized to phenylacetic acid.
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SM2
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if you want phenylacetaldehyde in copious amounts, react D-LPhenylalanine to a well stirred solution of strong bleech, or HTH. The yellow oil with
the sickly sweet smell is immediately apparent. Try to distill it out and separate ASAP, and make the bisulfite adduct, which IS stable.
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Nicodem
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But what exactly is wrong with the already published procedures for the styrene oxide to phenylacetaldehyde transformation?
I can understand the reluctance to consider some of the references for the rearrangement in the liquid phase which use non-trivial reagent or
conditions, but what for example is wrong with the procedure described in DOI: 10.1080/00397919508011817? Or US4650908 and DE3708737? The setup is
somewhat involved, but it is nothing that an average amateur could not do with some effort.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
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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SM2
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Nicodem;
My intuition tells me such a reaction benefits greatly from experience working the procedure. I recently had a straight forward synthesis fail on me,
and I did everything (or so I thought), strictly, according to the instructions. As to the beginning of your question "what is wrong...", I'd say the
person in question would prefer an easier route, like, for instance, titration until a color change occurs. The Styrene oxide
route>PhenylAcetaldehyde is far cheaper than starting from the pure amino acid as your feedstock.
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kristofvagyok
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I am reading an old (1995) Aldrichimica Acta and there is a reaction in it what fits to this topic.
It is about catalytic oxidative rearrangements made with Tl(III)-nitrate (TTL). There is 3 article mentioned here what are about to turn styrenes to
phenylacetaldehyde-dimethyl acetals by some methanol and some TTL.
Check them out, they could be interesting:
J. Am. Chem. Soc. 1973, 95, 3635
Liebigs Ann. Chem. 1962, 656, 204
S. Can. J. Chem. 1973, 51, 2366
P.S.: TTL is quite toxic, but it is needed in catalytic amounts, could be reused, and it is a pretty awesome reagent.
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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tetrahedron
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and especially OTC =)
check this out for more on that route:
McKillop, A., Hunt, J. D., Taylor, E. C., and Kienzle, F., "Thallium in Organic Synthesis: XX. Oxidative Rearrangement of Olefins with Thallium (III)
Nitrate--A Simple One-Step Synthesis of Aldehydes and Ketones," Tetrahedron Letters, No. 60, 1970, pp. 5275-5280.
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phendrol
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The reaction is attractive because there is no problem with acquiring the reagents where I live. Furthermore the peracid oxidation looks like it can
be run in a one pot reaction, which is very advantageous. Oxidation via the chlorohydrin uses OTC reagents and gives decent yields, but leads only to
styrene oxide. I'm wondering if it's possible to oxidize it further with hypochlorouse acid? Maybe a ring opening with an acid and rearrangement?
Anyway I'm waiting for my order of chemicals and after I'll get them I'm planning to do as follows
I'll prepare some performic acid by mixing formic acid with hydrogen peroxide. Next I'll prepare a solution of styrene in DCM with a sodium
carbonate/bicarbonate buffer. The performic acid will be then added dropwise to the solution with stirring left for 16 hours. Followed by extraction
of the organic phase, and after some work up, dissolving it in methanol and lightly boiling with dilute sulfuric acid.
As an alternative I was thinking about preparing the epoxide via the chlorohydrin route, then forming styrene glycol as described here:
http://www.scribd.com/doc/55131328/furanoside-rhee
and boiling it in methanol with dilute h2so4 to form the aldehyde.
[Edited on 27-11-2012 by phendrol]
[Edited on 27-11-2012 by phendrol]
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Nicodem
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Quote: Originally posted by phendrol  | | Followed by extraction of the organic phase, and after some work up, dissolving it in methanol and lightly boiling with dilute sulfuric acid.
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It appears to me that you did not do the literature work properly. There is a reason why silica-gel is used as an acid in that Synth. Commun.
article. Phenylacetaldehyde decomposes in such acidic environment as diluted sulfuric acid. Also, how is such an rearrangement supposed to be easier
than the given literature example which claims nearly quantitative yields, easy to obtain solvent and catalyst, and a ridiculously simple isolation?
You shouldn't be believing every nonsense that Fennel Ass Ih Tone manages to post - I bet he didn't even bothered reading the article before hitting
the reply button!
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phendrol
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Nicodem you are right.
The extra work up is not a big problem. Most of my work will be consumed by building an aspirator vacuum satation. I'll need it in the first step
(styrene --> chlorohydrin --> styrene oxide). Unless someone has an idea how to separate styrene oxide from unreacted styrene and side products
without using any vacuum. Maybe forming an azeotrope?
[Edited on 1-12-2012 by phendrol]
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phendrol
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I've managed to prepare some styrene oxide and I'm getting ready to rearrange it in the gas phase. I need an advice thou. I'm not sure how the silica
gel catalyst should be placed. Should it just be like a tube packed with silica dioxide powder or beads? Or should the catalyst be placed on
something?
I just don't want the whole thing to explode because of high pressure.
US4650908
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TheCatalyst
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Phendrol,
Have you had any success ? By the way why don't you use the liquid phase isomerization of styrene oxide. Seems to me it would be much easier.
Lemini, C. , Ordo≁ez, M. , Pérez-Flores, J. and Cruz-Almanza, R.(1995) 'Synthesis of Aldehydes from
Oxiranes using Silica Gel as Reagent', Synthetic Communications, 25: 18, 2695 — 2702
To link to this Article: DOI: 10.1080/00397919508011817
URL: http://dx.doi.org/10.1080/00397919508011817
General Procedure for the conversion of oxiranes into aldehydes. In a threenecked
round bottom flask equipped with a magnetic stirrer a solution of 1 g of
oxirane in 20 ml of ethylacetate or acetone was placed and, 1 g of silica gel was
added. The reaction mixture was stirred vigorously at room temperature until the
oxirane disappeared (monitoring by TLC). Most of the reactitvis were finished
within 30 min. When the reaction was completed the silica gel was removed by
filtration, the filtrate dried on Na,SO, and the solvent evaporated under reduced
pressure.
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phendrol
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Well to be honest I couldn't do much because I haven't got a vacuum pump. An aspirator is no good because water pressure is to low at my place.
Because of that I can't purify the epoxide via vacuum distillation. When I made a run with it, the silica gel was covering with tar pretty fast.
But this method sounds super easy. I definitely will try it and post results. Thanks!!!
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Nicodem
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An example of the acid catalyzed styrene oxide rearrangement to phenylacetaldehyde (applying H3PO4) and its concurrent
acetalization with another styrene oxide equivalent is described at the Synthetic Pages:
Acid mediated cyclodimerization of styrene oxide to 2-benzyl-4-phenyl-1,3-dioxalane; acetal formation (DOI:
10.1039/SP312)
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
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)
Read the The ScienceMadness Guidelines!
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Crowfjord
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Tetrahedron Letters 55 (2014) 5047–5051 describes the reactions of several amino acids with sodium hypochlorite in phosphate buffer. The buffer,
pH, dilute conditions, and slow addition are necessary to achieve good yields and avoid side reactions. From the supplementary materials:
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General Procedure for sodium hypochlorite oxidation. To a vigorously stirring solution of amino acid (1 mmol) in 250 mL of sodium phosphate buffer (10
mM, pH 7.0) was added a solution of NaOCl (1 equivalent as a 0.1 M aqueous solution) slowly over 10 minutes via syringe pump in a 37 °C warm room or
water bath. The resulting solution was stirred vigorously at this temperature until the reaction was judged to be complete by HPLC (1-2 hours). In
general, the reaction may be stopped after 2 hours if monitoring is inconvenient. The solution was then extracted into dichloromethane (4 x 40 mL),
washed with brine (2 x 50 mL), dried over MgSO4, and the solvent removed under reduced pressure in an unheated water bath to afford the desired
aldehyde.
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| Quote: | 2-phenylacetaldehyde (2e). DL-Phenylalanine (0.165 g, 1 mmol) was dissolved in 250 mL of 10 mM pH 7 phosphate buffer and reacted by
the above procedure for 2 hours to yield 72 mg of 2e (60 %) as a yellow oil. 1H-NMR, LRMS, and HPLC data matched an authentic commercial sample
(Sigma-Aldrich).
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clearly_not_atara
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Step 1: styrene + HBr + H2O2 >> phenethyl bromide
Step 2: http://pubs.acs.org/doi/abs/10.1021/ja01524a080?journalCode=...
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chemrox
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would you please post the pdf? in refs? or here..
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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clearly_not_atara
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Sure. The reaction is like this:
RHBr + AgOTs >> RHOTs + AgBr (s)
RHOTs + DMSO >> RO + HOTs + Me2S (g)
Silver tosylate is soluble in organic solvents but not water, so can be precipitated from a solution of AgNO3 and a tosylate. I do not know, but I
strongly suspect, that other sulfonic acids work just as well (as long as they're inert).
Attachment: tosylatealdehyde.pdf (684kB)
This file has been downloaded 819 times
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madcedar
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Thank you for the reference. My problem is with your Step 1, I think it makes styrene dibromide and not phenethyl bromide.
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DraconicAcid
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HBr will add across a double bond following Markovnikov's rule in the absence of peroxides, and add the other way in the presence of peroxides. The
hydrogen peroxide isn't going to turn the HBr into bromine.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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S.C. Wack
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Does there exist actual preparations that used hydrogen peroxide in step 1, that got a phenylacetaldehyde in step 2?
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clearly_not_atara
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See http://en.wikipedia.org/wiki/Markovnikov's_rule#Anti-Markovnikov_reactions
The method with HBr/cat. H2O2 is a classic; you can find examples in most chemistry textbooks (you can usually find a cheap one at charity
book-selling events and the like). Wiki does describe a synthesis of phenylacetaldehyde using a similar methodology with water and phenylacetylene.
See also:
http://www.chemicalforums.com/index.php?topic=58919.0
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madcedar
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Thank you for the clarification DraconicAcid and clearly_not_atara, great stuff.
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zed
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And then, there are modifications of the Wacker.
Looks interesting, maybe Iĺl finish reading it tomorrow.
http://www.google.com/patents/US7582750
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