Seperation of 2-phenylpropanal from P2P

TMO · Mon Jun 20, 2005 10:18 am

"It is not possible to effectively separate 2-phenylpropanal (bp 222°C/760mmHg) from phenyl-2-propanone (bp 214°C/760mmHg) through simple distillation and certainly not via vacuum distillation as the boiling points are too close. Fractional distillation could theoretically be used to separate them, but the size of the column that would have to be used makes that option impractical. A good idea for separating a mixture of the two is to oxidize the mixture with a mild oxidant which won't affect the P2P, but which will oxidize the aldehyde to 2-phenylpropionic acid. The acid can then be separated from the ketone by dissolving the mixture in a non-polar solvent and washing the solution with dilute sodium hydroxide. The P2P stays in the organic layer, which is then dried over MgSO4, the solvent removed under vacuum and the residue vacuum distilled to give pure P2P."

My question is can anyone recommend some oxidants to use for this seperation, preferably availible OTC? Would 30% H2O2 work with good stirring?

joe_aldehyde · huxleys associate

i guess H2O2 is just too strong. today i learned that bromine in water can safely oxidize aldehydes to acids, not touching secondary alcohols or ketones.

Elementary · Wed Jul 06, 2005 5:11 pm

Can use not be made of the bisulphite addition compound made with the ketone ?

I 've always been under the impression that most methyl ketones are resistant to further oxidisation with chromic acid. Oxidation of ketones requires breaking of carbon-carbon bonds and takes place only under vigorous conditions.

joe_aldehyde · huxleys associate

bisulfites react much better with aldehydes than ketones, so separation should be possible.

java · Consumer

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