THE ADDITION-REACTION OF DIALKYL CARBONATES TO KETONES

The reaction of benzyl phenyl ketone with dimethyl carbonate gives met hyl benzoate and methyl phenylacetate; diethyl carbonate gives the cor responding ethyl esters. The reaction takes place at high temperature (about 200-degrees-C) and in the presence of potassium carbonate as a catalyst. Other benzyl ketones react similarly. Aliphatic ketones yiel d a less selective addition. Accordingly, cyclohexanone with dimethyl carbonate gives dimethyl pimelate. The reaction is a retro-Claisen con densation, which occurs through the intermediate formation of the alko xycarbonyl derivative.