Process for the preparation of cinnamic acid

摘要

The invention relates to a process for the preparation of optionally substituted cinnamic acid by reacting ketene and optionally substituted benzaldehyde in the presence of zinc salts of carboxylic acids having a chain length of 6 to 18 C atoms as catalyst, followed by heating the reaction product to 100 to 250@C in the presence of acidic or basic catalysts. The reaction of the benzaldehyde with ketene in the presence of the zinc salts is carried out in the absence of water, carboxylic acids and carboxylic anhydrides.