It is type of condensation reaction, which involve the condensation of acidic anhydride and aldehyde in the presence of weak base (i.e. Sodium and potassium salt of the acid or trimethylamine) to give unsaturated carboxylic acid.(Equation-1)[1].In 1968 Perkin described the very first example of such type condensation reaction, involve the synthesis of coumarin by condensing the sodium or potassium salt of salicylaldehyde with acetic anhydride (Equation-2)[2].Generally such type of reaction is only applicable to aromatic aldehyde and useful for the preparation of substituted cinnamic acid (Equation-3)[3] Equation-1 Equation-2 Equation-3 In 1883.A very important variation is done by plӧchl, which involve the heating of benzaldehyde …show more content…
The compound 3 undergoes a minor potential side reaction decarboxylation to form an alkene (equation-5) Scheme-2(a) [1] Scheme-2(b) [X] …show more content…
Similar result were investigated earlier related to Perkin reaction of Quinone, [9]. When 2, 6-dimethoxy-p-bezoquinone treated with propionic anhydride in presence of sodium propionate gives a mixture of condensed product (12) and (13) Scheme-6 Although, when the same reaction is carried out in milder condition, the product (14) is isolated and it can be converted to 12 &13 in Perkin condition. It is observed that (14) may be in equilibrium with dimethoxybenzoquinone and methyl ketene. The isolation of product (14) does not prove that the product (14) is the reaction intermediate of product (12) and (13). So, we can conclude that the mechanism of the Perkin reaction is not as simple as indicated in Scheme-(2a&b). It may have more than the mentioned steps, it depends upon the nature of reacting species and