What is Perkin reaction?

The Perkin reaction is an organic reaction developed by English chemist William Henry Perkin that is used to make cinnamic acids. It gives an α,β-unsaturated aromatic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence of an alkali salt of the acid.The alkali salt acts as a base catalyst, and other bases can be used instead.

https://en.m.wikipedia.org/wiki/Perkin_reaction