Ethanoic acid is first converted to methane, which is then converted to ethyne, and finally polymerised to benzene.

First, ethanoic acid ($\text{CH}_3\text{COOH}$) is treated with $\text{NaOH(aq)}$ to form sodium ethanoate ($\text{CH}_3\text{COONa}$), which on heating with soda lime yields methane ($\text{CH}_4$).

Next, methane is converted to $\text{CH}_3\text{Cl}$ (using $\text{Cl}_2$), which undergoes Wurtz reaction with Na/dry ether to form ethane ($\text{C}_2\text{H}_6$). Ethane is then converted to $\text{C}_2\text{H}_5\text{Cl}$ (using $\text{Cl}_2$) and then to ethene ($\text{CH}_2=\text{CH}_2$). Ethene reacts with $\text{Br}_2$ to form $\text{CH}_2\text{Br}-\text{CH}_2\text{Br}$, which on treatment with alc. KOH gives $\text{CH}_2=\text{CHBr}$. This is further treated with $\text{NaNH}_2$ to form ethyne ($\text{CH}\equiv\text{CH}$).

Finally, ethyne undergoes cyclic polymerization by passing through a red hot iron tube at 873 K to form benzene.