Process for the preparation of unsaturated carboxylic acids

Acrylic or substituted acrylic acids are produced by treating the corresponding alkenal with an organic hydroperoxide as oxidizing agent in the presence of chromic acid as catalyst. Acrolein, a -methacrolein, a -chloracrolein, a -ethylacrolein, a -isobutylacrolein, and a -amylacrolein are mentioned and the reaction may take place in a mutual solvent such as t-butanol, t-amyl alcohol, dimethyl propyl carbinol, methyl diethyl carbinol and dimethyl phenyl carbinol and others. The chromic acid may be prepared in situ and hydroperoxides exemplified are t-butyl, cumene, cyclohexyl and cyclohex-2-enyl hydroperoxides and cyclohexanone peroxide or mixtures thereof.