Bromine → 2-Cyanobenzenesulfenyl bromide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

74.5 g (0.500 mol) of 2-cyanophenyl methyl sulfide and 250 g of chlorobenzene were placed in a 500 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 96.0 g (0.600 mol) of bromine was added dropwise thereto at about 100° C. over five hours while stirring, followed by stirring for two hours to complete the reaction. The excess bromine was removed with an aqueous sodium carbonate solution and the solvent was distilled off to obtain 92.0 g of crude 2-cyanobenzenesulfenyl bromide. Separately, 172.4 g (2.00 mol) of piperazine and 15 g of chlorobenzene were placed in a 1000 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and the molten crude 2-cyanobenzenesulfenyl bromide obtained above was added dropwise thereto at about 130° C. over one hour while stirring, followed by stirring for five hours to complete the reaction. The excess piperazine was removed with water and reaction mixture was acidified with hydrochloric acid, followed by extraction into an aqueous layer. The aqueous layer was basified with an aqueous sodium hydroxide solution to obtain 65.9 g of 3-(1-piperazinyl)-1,2-benzisothiazole as crystals. The yield starting from 2-cyanophenyl methyl sulfide was 60.2%.

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