Question

What is the mothod of preparation of cinnamic acid?

Answer 1

The original synthesis of cinnamic acid involves the Perkin reaction, which entails the base-catalysed condensation of acetic anhydrideand benzaldehyde. Rainer Ludwig Claisen (1851–1930) described the synthesis of cinnamate esters by the reaction of benzaldehydeand esters. The reaction is known as the Aldol condensation (with accompanying hydrolysis of the anhydride).

Synthesis of cinnamic acid via Perkin reaction

It can also be prepared from cinnamaldehyde and benzal chloride.

Another way of preparing Cinnamic acid is by the Knövenaegel–Hans condensation reaction. The reactants for this are the corresponding benzaldehyde and malonic acid in the presence of a weak base, followed by acid hydrolysis.