Oxidation of Benzyl Halides to Aldehydes and Ketones with Potassium Nitrate Catalyzed by Phase-Transfer Catalyst in Aqueous Media

Abstract

The catalytic oxidation of benzyl halides to aldehydes and ketones in aqueous media was studied under relatively mild reaction conditions by using phase-transfer catalyst combined with potassium nitrate and 10% aqueous potassium hydroxide solution. As a result, a simple high-yield procedure has been developed.

Keywords:

• Benzyl halide
• oxidation
• phase-transfer catalyst
• potassium nitrate

Notes

^a Reaction conditions: 4-isopropylbenzyl chloride (0.1 mol), H₂O (15 mL), reflux.

^b Isolated yield.

^c About 2 g cumenic acid (mp: 117–119 °C, lit.^[22] mp 118–120 °C) was obtained by acidifying the reaction aqueous solution with hydrochloric acid.

^d Added 10% KOH aqueous solution (60 mL, 0.1 mol) dropwise over the indicated time with a dropping funnel.

^a Reaction conditions: 4-isopropylbenzyl chloride (0.1 mol), KNO₃ (0.11 mol), H₂O (15 mL), PTC (1.1 mmol); 10% KOH aqueous solution (60 mL, 0.11 mol) added dropwise with a dropping funnel over 4 h, reflux.

^b Isolated yield.

^a Reaction conditions: benzyl halide (0.1 mol), KNO₃ (0.11 mol), H₂O (15 mL), CTAB (1.1 mmol), 10% KOH aqueous solution (60 mL, 0.11 mol) added dropwise with a dropping funnel over the indicated time, reflux.

^b Isolated yield.

^c An intractable mixture.

^d 2-Bromoethylbenzene was used.