Perkin Reaction Mechanism

What is Perkin Reaction?

Perkin Reaction is an organic chemical reaction which was discovered by William Henry Perkin, an English chemist. This reaction yields an α, β -unsaturated aromatic acid.

Perkin reaction mechanism includes the reaction between aromatic aldehydes, the aliphatic acid anhydride, and the alkali salt of the acid to give cinnamic acid derivatives. The Perkin reaction is an organic chemical reaction named after its discoverer – William Henry Perkin.

Example

The Perkin reaction gives an alpha, beta-unsaturated aromatic acid via the aldol condensation of an aromatic aldehyde and an acid anhydride. The alkali salt of the acid is also present. This alkali salt acts as a base catalyst. Other bases can be used instead of the alkali salt of the acid in the Perkin reaction.

Given below is an illustration of the Perkin reaction.

One of the most important applications of the Perkin reaction is the laboratory synthesis of phytoestrogenic stilbene resveratrol. The Perkin reaction can be considered as a type of condensation reaction.

Perkin Reaction Mechanism

Under the influence of the base, the anhydride gives the carbanion. This carbanion now attacks the carbonyl carbon of the aldehyde.

This attack yields an intermediate. The abstraction of a proton from the active methyl group of the intermediate by the given base and the subsequent elimination of the hydroxyl group gives unsaturated anhydride.

This product is now hydrolyzed to finally give alpha, beta-unsaturated acid. The illustration of the Perkin reaction mechanism is given below.

Thus, the required alpha, beta-unsaturated acid is formed.

It is important to note that the above-given mechanism is not universally accepted, as there are many other variations to the mechanism of Perkin reaction. One of these other mechanisms includes decarboxylation without the transfer of an acetyl group.

Frequently Asked Questions

Q1: Describe Perkin reaction.

A1: It is an organic chemical reaction that involves the aldol condensation of an organic acid anhydride and an aromatic aldehyde to yield an ɑ, ?-unsaturated aromatic acid.

Q2: What catalysts are used in the Perkin reaction?

A2: The alkali salt of the acid anhydride is used as a catalyst. However, other bases can be used for this purpose.

Q3: What are the applications of this named reaction?

A3: This reaction is used for the synthesis of phytoestrogenic stilbene resveratrol in the laboratory.

To learn more about the Perkin reaction and other named reactions in organic chemistry, such as the Hell-Volhard-Zelinsky halogenation reaction, Register with BYJU’S and download the mobile application on your smartphone.