Multiphase oxidation of alcohol to aldehyde
AssigneeThe Dow Chemical Company
InventorKing W. Ma
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Abstract
In a two-phase liquid medium comprising an aqueous alkaline solution and an organic solvent, molecular oxygen and a noble metal-containing catalyst can be used to oxidize aryl-substituted alcohols of the formula AR(--CH.dbd.CH--).sub.n CH.sub.2 OH wherein n is 0, 1 or 2, to the corresponding aldehydes. More specifically, the oxidation of an aromatic alcohol, such as p-methoxybenzyl alcohol, can be efficiently carried out in a multiphase system comprising a 5 percent palladium-on-charcoal catalyst, an organic solvent such as methylene chloride, in contact with an aqueous sodium hydroxide solution, in the presence of air or oxygen with good agitation followed by separation of the two phases, recovery of the aldehyde product from the organic solvent and recycle of the aqueous phase without neutralization.
Claims10
A process for the production of an aromatic aldehyde consisting essentially of the following steps:
- (a) subjecting an aryl-substituted alcohol of the formula:
- Ar(--CH.dbd.CH--).sub.n CH.sub.2 OH
- wherein n is 0, 1 or 2, and Ar is an aromatic radical having at least one benzene ring, to the action of molecular oxygen in the presence of a noble metal catalyst in a two-phase liquid reaction medium consisting of an organic phase comprising an inert, water-immiscible organic liquid which is a solvent for the aromatic aldehyde produced, and an aqueous phase comprising an aqueous alkaline solution, at a temperature below the decomposition temperature of the alcohol;
- (b) at the end of the reaction time, separating the organic phase from the aqueous phase, and isolating the resulting aldehyde from the organic phase;
- and
- (c) recycling the separated aqueous phase without neutralization for subsequent reuse as the aqueous phase in step (a).
Dependencies are inferred from the claim text.