How do esters undergo hydrolysis?

Esters undergo hydrolysis by reacting with water to form a carboxylic acid and an alcohol.

Esters are organic compounds that are derived from carboxylic acids. They are characterised by a carbonyl group (C=O) adjacent to an ether group (R-O-R'). Hydrolysis is a chemical reaction in which a molecule is split into two parts by the addition of a water molecule. In the case of esters, hydrolysis results in the formation of a carboxylic acid and an alcohol.

The hydrolysis of esters can occur under either acidic or basic conditions. Under acidic conditions, the reaction is a reversible process. The ester reacts with water in the presence of an acid catalyst, usually a strong acid like sulphuric acid. The carbonyl carbon of the ester is protonated by the acid, making it more susceptible to nucleophilic attack by a water molecule. This forms a tetrahedral intermediate, which then loses a proton to return to the carbonyl form and release an alcohol.

Under basic conditions, the hydrolysis of esters is an irreversible process known as saponification. In this reaction, the ester reacts with a hydroxide ion (OH-) instead of a water molecule. The hydroxide ion acts as a nucleophile and attacks the carbonyl carbon of the ester, forming a tetrahedral intermediate. This intermediate then loses a proton to form a carboxylate ion and an alcohol. The carboxylate ion can then react with a proton to form a carboxylic acid.

The rate of hydrolysis of esters is influenced by several factors, including the structure of the ester, the temperature, and the pH of the solution. Generally, the reaction rate increases with increasing temperature and pH. The presence of a catalyst can also significantly increase the reaction rate.

In summary, esters undergo hydrolysis by reacting with water or a hydroxide ion to form a carboxylic acid and an alcohol. This reaction can occur under either acidic or basic conditions, and is influenced by several factors including temperature, pH, and the presence of a catalyst.