toluen + br2

Abstract

The photoirradiation of toluene derivatives with two equivalents of bromine in benzotrifluoride–water provided a satisfactory yield of the corresponding benzoic acid derivatives. Either a fluorescent lamp, xanh rì LED (454 nm), or UV LED (385 nm) was used for the photoreaction. The reaction pathway might proceed through the dibromination of benzylic carbon, generation of the benzylic radical via oxidative C–H abstraction, formation of benzoyl bromide, and hydrolysis of carboxylic acid.

Publication History

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• References and Notes

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• 10 Typical Experimental Procedure A 100 mL Pyrex flask was charged with 1-cyano-4-methylbenzene ( p-1a, 586 mg, 5.0 mmol) and Br₂ (840 mg, 10.5 mmol) in BTF (30 mL) and water (6 mL). The attached reflux condenser was open air, and the flask was irradiated with a 13 W white fluorescent lamp at intervals of 5 centimet with vigorous stirring for 24 h. The reaction mixture was combined with saturated aqueous NaHCO₃ and EtOAc. The alkaline aqueous layer was then separated and acidified with diluted HCl. The solution was successively extracted using EtOAc and washed with H₂O and brine. After drying over anhydrous Na₂SO₄, it was concentrated to lớn produce 4-cyanobenzoic acid ( p-2a, 684 mg, 93%) colorless crystals. The sample was sufficiently pure, and further purification was not performed. 4-Cyanobenzoic Acid (p-2a) Mp 222 °C (lit.¹¹ mp 221 ℃). ¹H NMR (400 MHz, CD₃OD): δ = 8.11 (d, J= 8.4 Hz, 2 H), 7.79 (d, J = 8.4 Hz, 2 H). ¹³C NMR (101 MHz, CD₃OD): δ = 167.9, 135.9, 133.3, 131.2, 118.9, 117.1.
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• Supplementary Material