per·kin reaction noun alsoperkin synthesis\ˈpərkə̇n-\ Usage: usually capitalized P Etymology: after Sir William Henry Perkin died 1907 English chemist : a reaction for making an unsaturated aromatic acid (as cinnamic acid) by heating an aromatic aldehyde with an acid anhydride (as acetic anhydride) in the presence of a base (as sodium acetate or potassium carbonate)