Question

What is the nucleophile in Fischer Esterification?

Answer 1

The alcohol........

Explanation:

For the general esterification rxn we write:

`ROH + R'CO_2H rarr R'CO_2R + H_2O`

Sometimes the reaction is made more facile by using the acid halide in place if the carboxylic acid. Anyway, clearly the alcohol is the electron donor, that reacts with the carbonyl, and forms a `C-O` bond.

The fact that the rxn spits out water, which can be removed from the equilibrium by azeotropic distillation, can drive the reaction to completion.