Direct and Facile Oxidative Conversion of Primary, Secondary, and Tertiary Amines to Their Corresponding Nitriles

Abstract

Molecular iodine in aqueous ammonia at 60 °C efficiently oxidized various primary, secondary, and tertiary amines to their corresponding nitriles in good yields.

amines - iodine - nitriles - aqueous ammonia

References and Notes

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9

Oxidative Conversion of Primary Amines to Nitriles; Typical Procedure: To a mixture of 4-methylbenzylamine (121.2 mg, 1 mmol) and aq NH₃ (3.0 mL, 45 mmol) under an empty balloon was added I₂ (533.0 mg, 2.1 mmol) at r.t. The resulting mixture was stirred at 60 °C. After 2 h at the same temperature, the reaction mixture was quenched with H₂O (20 mL) and a sat. aq solution of Na₂SO₃ (3 mL) at 0 °C. The product was extracted with Et₂O (3 × 15 mL). The organic layer was washed with brine and dried over Na₂SO₄ to provide p-tolunitrile in 80% yield in an almost pure state. If necessary, the product was purified by column chromatography (silica gel; hexane-EtOAc, 4:1) to give pure p-tolunitrile as a colorless solid; mp 25 °C. IR (NaCl): 2230 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 2.42 (3 H, s), 7.27 (2 H, d, J = 7.9 Hz), 7.55 (2 H, d, J = 7.9 Hz). The identity of the product was confirmed by comparison of its analytical data with a sample of the commercially available authentic compound.Oxidative Conversion of Tertiary Amines to Nitriles; Typical Procedure: To a mixture of N,N-dimethyl-3-phenylpropylamine (163.2 mg, 1 mmol) and aq NH₃ (3.0 mL, 45 mmol) under an empty balloon was added I₂ (888.3 mg, 3.5 mmol) at r.t. The resulting mixture was stirred at 60 °C. After 0.5 h at the same temperature, the reaction mixture was quenched with H₂O (20 mL) and a sat. aq solution of Na₂SO₃ (3 mL) at 0 °C. The product was extracted with Et₂O (3 × 15 mL). The organic layer was washed with brine and dried over Na₂SO₄ to provide 3-phenylpropionitrile in 71% yield in an almost pure state. If necessary, the product was purified by column chromatog-raphy (silica gel; (hexane-EtOAc, 4:1) to give pure 3-phenylpropionitrile as a colorless oil. IR (NaCl): 2250 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 2.62 (2 H, t, J = 7.4 Hz), 2.96 (2 H, t, J = 7.4 Hz), 7.23 (2 H, d, J = 8.1 Hz), 7.28 (1 H, t, J = 8.2 Hz) 7.34 (2 H, t, J = 8.2 Hz). The identity of the product was confirmed by comparison of its analytical data with a sample of the commercially available authentic compound.Oxidative Conversion of Tris(4-methylbenzyl)amine to p -Tolunitrile: To a mixture of tris(4-methylbenzyl)amine (329.5 mg, 1 mmol) and aq NH₃ (3.0 mL, 45 mmol) under an empty balloon was added I₂ (1.650 g, 6.5 mmol) at r.t. The resulting mixture was stirred at 60 °C. After 4 h at the same temperature, the reaction mixture was quenched with H₂O (20 mL) and a sat. aq solution of Na₂SO₃ (3 mL) at 0 °C. The product was extracted with Et₂O (3 × 15 mL). The organic layer was washed with brine and dried over Na₂SO₄ to provide p-tolunitrile in 84% yield in an almost pure state. If necessary, the product was purified by column chromatog-raphy (silica gel; hexane-EtOAc, 4:1) to give pure p-tolu-nitrile as a colorless solid; mp 25 °C. IR (NaCl): 2230 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 2.42 (3 H, s), 7.27 (2 H, d, J = 7.9 Hz), 7.55 (2 H, d, J = 7.9 Hz).