Question

Show how each of the following compounds can be converted to benzoic acid:
(I) Acetophenone
(II) Ethyl benzene

Hint:

In side-chain oxidation of alkylbenzenes, the entire alkyl group is oxidized to a single \(-COOH\) group, no matter how many carbons are in the chain.

Answer 1

Show how each of the following compounds can be converted to benzoic acid:
(I) Acetophenone
(II) Ethyl benzene
Solution:
(I) Conversion of Acetophenone to Benzoic Acid:
Acetophenone (\( \text{C}_6\text{H}_5\text{COCH}_3 \)) contains a methyl group attached to a carbonyl group. One way to convert acetophenone to benzoic acid is by using the oxidation reaction. The methyl group can be oxidized to a carboxyl group using strong oxidizing agents like potassium permanganate (KMnO₄) or chromic acid (H₂CrO₄), which will oxidize the methyl group (-CH₃) to a carboxyl group (-COOH), forming benzoic acid. The reaction is:
\[ \text{C}_6\text{H}_5\text{COCH}_3 \xrightarrow{KMnO_4} \text{C}_6\text{H}_5\text{COOH} \] (II) Conversion of Ethyl Benzene to Benzoic Acid:
Ethyl benzene (\( \text{C}_6\text{H}_5\text{CH}_2\text{CH}_3 \)) can be converted to benzoic acid through oxidation of the ethyl group to a carboxyl group. A common method involves using potassium permanganate (KMnO₄) or other strong oxidizing agents. The ethyl group (-CH₂CH₃) gets oxidized to a carboxyl group (-COOH), converting ethyl benzene to benzoic acid. The reaction is:
\[ \text{C}_6\text{H}_5\text{CH}_2\text{CH}_3 \xrightarrow{KMnO_4} \text{C}_6\text{H}_5\text{COOH} \]