Question: What carboxylic acid and alcohol are needed to prepare each ester by Fischer esterification?

a.

b.

Esters are synthesized from alcohol and carboxylic acids.

Carboxylic acids are inactive towards esterification, and therefore, require activation. Therefore, catalysts are used.

Catalysts can be acids or bases. If the catalyst used is a mineral acid, the esterification reaction is called Fischer esterification.

In this method, the acid and alcohol refluxed in the presence of the acid.

Consider an ester RCOOR.

In this compound, the carbonyl part (RCO) comes from the carboxylic acid, and the alkoxy part (R’O) comes from the alcohol.

Therefore, to find the parent acid and alcohol of an ester, the C-O bond in ester is broken, and the structure of the corresponding acid and alcohol is completed.

a. The given ester is cyclohexyl benzoate.

Therefore, the acid and alcohol required to prepare this ester are shown below.

Retroanalysis of cyclohexyl benzoate

b. The given ester is isobutyl isobutyrate.

Therefore, the acid and alcohol required to prepare this ester are given below.

Retroanalysis of isobutyl isobutyrate