The Perkin reaction 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. Here is an a diagram showing what the reaction does
The anion of the salt acts as a base for abstracting the β-hydrogen in the acid anhydride. Later it attacks the carbonyl carbon of an intermediate but however leaves in the same step. Since the base is not ultimately involved in the product, is there any kinetic or thermodynamic reason as to why the salt of the acid of the acid anhydride is preferred over any other base?