1. NUCLEOPHILIC SUBSTITUTION REACTION CARBOXYLIC ACID AND ITS DERIVATIVES NUCLEOPHILIC ADDITION to a carbonyl group as the first step

2. NUCLEOPHILIC SUBSTITUTION REACTION CARBOXYLIC ACID AND ITS DERIVATIVES Rearrange the pi-bonding electron pair: Move them to the more electronegative oxygen. This maintains the tetravalency of carbon.

3. NUCLEOPHILIC SUBSTITUTION REACTION CARBOXYLIC ACID AND ITS DERIVATIVES Since X is a good leaving group, the negative charge on the oxygen will be involved in ejecting the group X and re-establish the C=O bond thus completing the reaction. ELIMINATION OF GROUP X

4. NUCLEOPHILIC SUBSTITUTION REACTION CARBOXYLIC ACID AND ITS DERIVATIVES Overall process: Nucleophilic Addition followed by Elimination of X