Abstract: The present invention provides a method for producing a 1,2-benzisothiazol-3-one compound by reacting a 2-(alkylthio)benzonitrile compound with a halogenating agent in the presence of water, wherein an alkyl halide that is generated as by-product is reacted with a sulfide to form an alkylthiol, which is converted into an alkali metal salt, and then the resulting alkali metal salt is reacted with a 2-halobenzonitrile compound to be converted into a 2-(alkylthio)benzonitrile compound and reused as a starting material for the production of a 1,2-benzisothiazol-3-one compound. By means of the present invention, it is possible to efficiently use the by-product that is generated during the production of a 1,2-benzisothiazol-3-one compound and economically produce a 1,2-benzisothiazol-3-one compound without placing a burden on the environment.

Abstract: A method of purifying crude pyridine on an industrial scale at low cost and in a simple manner is provided. More specifically, a pyridine purification method including subjecting crude pyridine to an alkali treatment and then to distillation, or a pyridine purification method including adding an acid or water to crude pyridine, and subjecting the resulting mixture to an alkali treatment and then to distillation is provided. According to the purification method of the present invention, crude pyridine can be purified on an industrial scale at low cost and in a simple manner. Moreover, the pyridine purified by this method is useful as a starting material for various organic syntheses because of its high purity. For example, the pyridine can be reacted with chlorine to produce a chlorinated pyridine in a high yield.