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Author: Subject: eugenol -->vanillin
spirocycle
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[*] posted on 28-2-2011 at 06:18
eugenol -->vanillin


I know that with side chain oxidation, eugenol can be oxidized to the corresponding carboxylic acid, but would it be possible to limit this oxidation to stop at the aldehyde?
I saw a mention of this in the vanillin thread, but there were no specifics.
I know I'm supposed to cite a reference here,
so:
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/benz...

section 5 explains permanganate side chain oxidation

distillation wouldnt work, because eugenol is more volatile than vanillin.
possibly reacting it in a solvent that eugenol and the acid are soluble in, but vanillin isnt.
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Hexagon
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[*] posted on 28-2-2011 at 06:41


What? You've got to isomerize eugenol to isoeugenol and then oxidize the double bond to vanillin, that's how it was made in the old days, I think that they used dichromate, search google pats. for a ref.
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entropy51
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[*] posted on 28-2-2011 at 06:54


There's already a thread on this, einstein. The search engine popped it right up.



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Sobrero
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[*] posted on 28-2-2011 at 07:23


Recently I was reading in "Electrochemistry of Organic Compounds", Walther Löb, 1906 (available in the SMDB library), and it mentions on page 202 a Deutsche Reich Patent DE92007 in which eugenol is electrolytically oxidized to vanilin. However, I'm unable to find the (1895) patent. Challenge anyone? :)



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spirocycle
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[*] posted on 28-2-2011 at 17:56


Quote: Originally posted by Hexagon  
What? You've got to isomerize eugenol to isoeugenol and then oxidize the double bond to vanillin, that's how it was made in the old days, I think that they used dichromate, search google pats. for a ref.


so the alkene reactivity takes priority over the aromatic side chain reactivity?
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mnick12
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[*] posted on 28-2-2011 at 21:06


Huh?
The reason why one isomerizes eugenol to isoeugenol is so that the double bond can be cleaved with the appropriate oxidizing agent into the aldehyde.
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[*] posted on 1-3-2011 at 05:36


Yeah, the other way you would obtain homovanillin (the substituted phenyl acetaldehyde) and AFAIK if you would obtain vanillin would be through overoxidation since the benzyl carbon is so prone to oxidation.
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[*] posted on 2-3-2011 at 12:01


Is phenylactaldehyde useful in benzedrin synth?
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spirocycle
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[*] posted on 2-3-2011 at 12:35


Quote: Originally posted by mnick12  
Huh?
The reason why one isomerizes eugenol to isoeugenol is so that the double bond can be cleaved with the appropriate oxidizing agent into the aldehyde.

i asked this because in chem class, we learned at aromatic alkyl groups are always cleaved to the methanoate.

So i was confirming that the alkene oxidation rules supercede the aromatic alkyl rules for oxidation
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