Question:

1. The Key Mechanism for Fischer esterification omitted some important resonance forms of the intermediates shown in brackets. Complete the mechanism by drawing all the resonance forms of these two intermediates.
2. Propose a mechanism for the acid-catalyzed reaction of acetic acid with ethanol to give ethyl acetate.
3. The Principle of Microscopic Reversibility states that a forward reaction and a reverse reaction taking place under the same conditions (as in equilibrium) must follow the same reaction pathway in microscopic detail. The reverse of the Fischer esterification is the acid-catalyzed hydrolysis of an ester. Propose a mechanism for the acid-catalyzed hydrolysis of ethyl benzoate, $PhCOOC{H}_{2}C{H}_3$.

Fischer esterification is the conversion of carboxylic acid to an ester in the presence of strong acid catalyst and excess alcohol. The solvent used in Fischer esterification is ethanol.

Resonance forms of two intermediates

Acid-catalyzed reaction is a reaction catalyzed by acid, and these acid catalysts accelerate the chemical reaction.It facilitates the nucleophilic attack of alcohol at the carbonyl carbon of a carboxylic acid.

In step A, a proton is added, and resonance structures are formed.

In step B, the nucleophile attacks the carbon.

In step C, proton off occurs.

In step D, a proton is added again.

In step E, leaving of leaving group and resonance structures are formed.

In step F, proton off occurs.

The mechanism for acid-catalyzed reaction