Q.72. - Organic Chemistry

Question

Question: Draw a stepwise mechanism for the following reaction.

Step-by-Step Solution

Answer

Answer

The stepwise mechanism involves the epoxidation of the starting material by m-CPBA, followed by the attack of m-chloro benzoic acid, causing the epoxide ring-opening.

The product abstracts hydrogen from another acid, forming a carboxylate ion as a byproduct.

The carboxylate ion abstracts hydrogen from the hydroxyl group eliminating the positive charge on oxygen.

Step 1: Organic synthesis

The synthesis of complex organic compounds from simpler compounds by a series of steps is called organic synthesis.

In organic synthesis, the main steps include oxidation and reduction.

Each synthetic step of organic synthesis will be a reaction between 2 reagents, the product of which is reacted in the next step.

Step 2: Epoxidation reaction

The addition of peroxy acids to a double bond to form an epoxide is called epoxidation.

Epoxides are cyclic ether formed by the syn addition of an oxygen atom to a double bond.

These epoxides undergo ring-opening reactions because the strain in the three-membered ring is very high.

These ring-opening reactions are used for chain extension without losing molecules as byproducts.

Step 3: Mechanism of given conversion

In the first step, the starting material undergoes epoxidation in the presence of m-CPBA to form an epoxide. m-CPBA is then converted to m-chloro benzoic acid.

Epoxidation using m-CPBA

 

The epoxide formed undergoes ring-opening by the attack of m-chloro benzoic acid.

Attack of m-chloro benzoic acid

 

This is followed by two hydrogen abstraction reaction that neutralizes the charges in the compound. The first hydrogen is abstracted from m-chloro benzoic acid.

The acid's conjugate base formed during this reaction abstracts hydrogen from the hydroxyl group to form a neutral product.