Chromic acid oxidation alkylbenzenes

Side chains of alkylbenzenes are oxidized to benzoic acid derivatives by treatment with hot potassium permanganate or hot chromic acid. Because this oxidation requires severe conditions, it is useful only for making benzoic acid derivatives with no oxidizable functional groups. Oxidation-resistant functional groups such as —Cl, —NO2, —SO3H, and —COOH may be present (Section 17-15A). 

Interestingly, however, alkylbenzenes are readily oxidized by chromic acid. The oxidation takes place selectively at the benzylic position ... 

Alkylbenzenes are oxidized at the benzylic position by chromic acid or potassium permanganate. 

Alkylbenzenes can be distinguished from primary and secondary alcohols by their failure to give a positive chromic anhydride test. Recall, primary and secondary alcohols are oxidized by chromic anhydride, CrOs/ in aqueous sulfuric acid. Within two seconds, the clear orange solution turns blue-green and becomes opaque as shown ... 

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