Draw the conjugate base for each compound below (the acidic hydrogen in each case is marked with an *).

(d)

Benzoic acid

It is a carboxylic acid, its chemical formula is${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}$. Its IUPAC name is benzoic acid. It is an aromatic compound as it follows Huckle’s rule. It is a cyclic compound having 6 pi-conjugated electrons. It is an acidic compound as it contains a carboxylic group. It is used in chemical industries and also used as a preservative in foods.

The hydrogen atom marked with (*) is the most acidic. It is directly attached to the electronegative oxygen atom, which is directly attached to the carbonyl group. Therefore, that oxygen atom will withdraw electron density from the hydrogen atom, making it most acidic hydrogen atom.We will get the conjugate base of the acidic compound when the hydrogen ion is released.

Therefore, the conjugate base of benzoic acid is:

Conjugate base of benzoic acid