Cinnamic acid is found both in free form, and especially in the form of esters (ethyl, Cinnamyl, benzyl), in various essential oils, resins and balsams,oil of cinnamon, balsam of Peru, of Tolu, vanilla extract etc..
It was observed Trommsdorf first time in 1780,in oil of cinnamon, but it was confused with benzoic acid. Its structure was established by Dumas and Peligot in 1835, and the first synthesis from benzaldehyde and acetyl chloride was made by Bertagnini in 1856. The process became a classic, the synthesis from benzaldehyde and it was prepared by Perkin in 1877.
The most used method of preparation of cinnamic acid on an industrial scale, is the synthesis Perkin. It also is used on an industrial scale the Knoevenagel method from benzaldehyde and Malonic acid in the presence of amines (pyridine or benzyl amine), or process from benzylidene chloride and excess of sodium acetate at 180 ... 200C.
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