Revisiting Sodium Hypochlorite Pentahydrate (NaOCl·5H₂O) for the Oxidation of Alcohols in Acetonitrile without Nitroxyl Radicals

Abstract

Sodium hypochlorite pentahydrate (NaOCl·5H₂O) is capable of oxidizing alcohols in acetonitrile at 20 °C without the use of catalysts. The oxidation is selective to allylic, benzylic, and secondary alcohols. ­Aliphatic primary alcohols are not oxidized.

Key words

oxidation - alcohol - sodium hypochlorite pentahydrate - ­aldehyde - ketone

• References and Notes

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• 7 Oxidation of 2-Octanol; Typical Procedure (entry 10, Table 2): To a suspension of NaOCl·5H₂O crystals (123 mg, 0.75 mmol) in acetonitrile (5.0 mL), was added 2-octanol (65 mg, 0.50 mmol), and the resulting mixture was stirred at 20 °C. Aliquots were analyzed at intervals by GC after passing through a short SiO₂ column (eluting with EtOAc/hexane, 9:1). The reaction was stopped after 1 h by quenching with Na₂SO₃ (94 mg, 0.75 mmol) and the mixture was diluted with CH₂Cl₂ (10 mL). The yield of 2-octanone (t_R : 2.1 min) and the recovery of 2-octanol (t_R : 2.8 min) were determined to be 91% and 2%, respectively, by GC analysis based on a calibration curve using authentic samples.
• 8 Oxidation of 1,5-hexanediol (Scheme 3): To a suspension of NaOCl·5H₂O crystals (123 mg, 0.75 mmol) in acetonitrile (5.0 mL), was added 1,5-hexanediol (59 mg, 0.50 mmol), and the resulting mixture was stirred at 20 °C. The reaction was stopped after 1 h by quenching with Na₂SO₃ (95 mg, 0.75 mmol). The product was analyzed by ¹H NMR and found to be 6-hydroxyhexane-2-one (31%, δ = 2.49 ppm, 2 H) and 1,5-hexanediol (49% recovery, δ = 1.20 ppm, 3 H) based on a standard material (triphenylmethane δ = 5.55 ppm, 1 H).