LSD25
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Synthesis of Phenylpropan-1,2-dione via acetylene?
I just found the linked article while looking for a decent route to acetaldehyde from acetylene. It suggests that the researchers worked out a route
to phenylpropan-1,2-dione from benzaldehyde and acetlyene in 3 steps: (1) Condensing acetylene with benzaldehyde over copper; (2) adding water to the
formed propagylic alcohol over a mercury salt; and (3) oxidation of the phenylpropan-1-ol-2-one to the dione.
As this seems to be a incredibly interesting route by which to go, I'd appreciate some informed comment upon how the reaction (particularly the first
one) goes and under what conditions it would work... I mean obviously it goes via the acetylide, but how could they avoid having to use the more
reactive metals?
Also, is there any way to avoid using mercury salts in the second step?
This one should cause some interest
http://www.journalarchive.jst.go.jp/jnlpdf.php?cdjournal=pja...
[Edited on 8-3-2008 by LSD25]
Whhhoooppps, that sure didn't work
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not_important
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Copper and silver, often with traces of bismuth or other metals, are common catalysts for the addition of alkynes to carbonyl groups. Strongly basic
ion exchange resins can be used, even strong inorganic bases although they tend to cause competing reactions of the carbonyls especially aldehydes.
Mercury is the catalyst for the addition of water or alcohols to alkynes, Tl(III) also works. Amines can be added as well, see Russ. Chem. Rev. 34,
669-680 (1965)
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LSD25
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Is the addition of the alkyne to the benzaldehyde a named reaction? It is just that this would probably make it easier for me to find out something
more about this particular reaction.
I am somewhat uneasy about copper catalysts with acetylene (for fairly obvious reasons), I did find this thesis/dissertation about similar reactions,
some of which are named but I cannot sort out which is which:
http://e-collection.ethbib.ethz.ch/ecol-pool/diss/fulltext/e...
Obviously the triflate variant is out of reach, but the ZnCl2 approach might be worth considering, especially if it removes the need for high pressure
during the initial reaction (although high-pressure isn't precisely the problem).
Lastly, which Ti(III) salts can be used? More importantly, can TiCl3 be used?
Whhhoooppps, that sure didn't work
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Nicodem
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| Quote: | Originally posted by LSD25
Lastly, which Ti(III) salts can be used? More importantly, can TiCl3 be used? |
Tl as for thallium, not titanium. You don't really want to work with Tl salts anyway.
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LSD25
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Sorry,
My eyes are absolutely slitted right at the moment - big night of study followed by a little research for fun....
I'll have another look in about 8 hours when my eyes open up again properly
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smuv
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Well...If you need a way of continuously producing ephedrine this is OK. But that first step can be accomplished in a much simpler (and SAFER!!!)
manner suitable for batch production.
An Alkyne can be deprotonated yielding an acetylide (a good nucleophile). This acetylide can add to a carbonyl bond in a manner very reminiscent to
the gringard reaction. I am nearly positive the procedure you posted catalylically produces an acetylide species in vapor phase and proceeds
similarly.
See orgsynth for a simular prep (there are probably many others like this)
I also want to say that the above procedure is very dangerous for a home chemist. For a long time in most industrialized countries there were
regulations against the usage of acetylene under pressure. In Germany the maximum was 1.5 atmg. With the advent of the Reppe pressure process to
produce vinyl ethers (at 12atmg) this restriction was reviewed. It was shown that acetylene was liable to explode under conditions needed to carry
out various reactions and this risk could not be eliminated. Although, the explosions could be prevented from becoming detonations and could be
confined within sections of the plant with proper accommodations for the pressure rise. In short you can't do this safely at home.
^^From: Acetylene Its Properties Manufacture and Uses Vol 1. By SA Miller.
[Edited on 8-3-2008 by smuv]
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LSD25
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Sorry - was not being rude intentionally had rather a lot to do yesterday,
I just had a quick look and what do I see:
https://sciencemadness.org/talk/viewthread.php?fid=10&ti...
| Quote: | Originally posted by trilobite:
Here is the full abstract. Note that the researchers do not prepare 1-phenyl-2-propyn-1-one at all, obviously PhCOEt really IS propiophenone, prepared
in several steps from benzaldehyde.
Acetylenic alcohol and its derivatives. IV. Synthesis of propiophenone and 3,4-methylenedioxypropiophenone. Hirao, Ichiro. Ono Pharmaceutical Co.,
Yakugaku Zasshi (1953), 73 1224-6.
Abstract
BzH (4 kg.) in 7 l. 90% MeOH in an autoclave with C2Cu2 is adjusted to pH 7.8 with NaOH, charged to 10-15 atm. with C2H2, heated 4-5 hrs. at 120°,
and the product extd. with Et2O and distd. to give PhCH(OH)C.tplbond.CH (I), b14 114-16°; benzoate, m. 81-3°; phenylcarbamate, m. 73-5°. Catalytic
reduction of 60 g. I in 150 ml. MeOH with 5 g. Raney Ni and 60 atm. H 30 min. at 40° gives 58 g. PhCH(OH)Et (II), b15 108-10°; similarly is prepd.
3,4-CH2O2C6H3CH(OH)Et (III), b12 143-4°. II (39 g.) added dropwise to 45 g. K2Cr2O7, 60 g. H2SO4, and 400 ml. water, the mixt. stirred 1 hr. at
25-30°, and the product extd. with Et2O and distd. gives 36 g. PhCOEt, b7 85-6°; semicarbazone, m. 176-7°; similarly is prepd. 3,4-CH2O2C6H3COEt,
b4 124-7°, m. 38-9°. A mixt. of 50 ml. 75% MeOH and 0.6 g. H2SO4 at 60° treated with 0.6 g. HgSO4 and 26 g. PhCOEt in 20 ml. MeOH, heated 5-6 hrs.
at 60°, the product neutralized with Na2CO3, the MeOH removed, and the residue extd. with Et2O and distd. gives 18 g. BzCOMe, b13 151-2°;
disemicarbazone, m. 226-30°.
Here is a P2P synth by the same researcher which uses the alkyne hydration reaction on 1-phenyl-2-propyn-1-ol.
Phenylethynylcarbinol and its derivatives. II. Synthesis of phenylacetone. Hirao, Ichiro. Osaka Univ., Nippon Kagaku Kaishi (1921-47) (1953), Ind.
Chem. Sect. 56 265-6.
Abstract
Com. PhCH(OH)C.tplbond.CH was hydrated with H2SO4 to PhCH(OH)COCH3, which was hydrogenated with Raney-Ni catalyst by H of 50 atms. in an autoclave at
room temp. The white crystals obtained correspond to 1,2-dihydroxy-1-phenylpropane (I) of m.p. 91-92°; yield, 95%. PhCH2Ac was prepd. by treating of
I with H2SO4, oxalic acid, H3PO4, etc. at the b.p. of the soln.; yield, approx. 73%
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Whhhoooppps, that sure didn't work
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