Basic hydrolysis of esters produces:

Carboxylates

The correct answer is option 1. Carboxylates.

When esters are treated with sodium hydroxide, they are converted into carboxylate salts, which upon neutralization yield carboxylic acids. This process is called basic hydrolysis of esters, or saponification. Hydrolysis occurs via a twostep addition-elimination mechanism (nucleophilic acyl substitution). The carboxylic acid is then deprotonated to give a carboxylate. To get the final carboxylic product, acid is added during the workup step.

The Mechanism for Basic Hydrolysis

The first step in saponification is nucleophilic addition of the hydroxide ion to the carbonyl carbon of the ester to form a tetrahedral intermediate. This is followed by elimination of alkoxide \((RO^–)\) from the tetrahedral intermediate to give a carboxylic acid.

This two step addition-elimination process is an example of nucleophilic acyl substitution

Since base is present, however, and since carboxylic acids (\(pK_a\) around 4-5) are much more acidic than alcohols (\(pK_a\) around 15-16), the carboxylic acid is then quickly deprotonated to give the conjugate base of the carboxylic acid, called a carboxylate salt.

To obtain the neutral carboxylic acid, one generally adds strong acid to the aqueous solution of carboxylate until the carboxylic acid precipitates out, and we then perform an extraction with an organic solvent.