438-41-5

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A disclosed method for preparing chlordiazepoxide hydrochloride with small hygroscopicity comprises the following steps: (1) successively adding chlordiazepoxide and a micromolecule linear-chain aliphatic ketone, and stirring to raise the temperature to a reaction temperature, slowly dropwise adding a hydrogen chloride acetone solution, after dropwise adding is finished, performing warm-keeping reaction, and filtering while hot, washing, filtering thoroughly and drying, so as to obtain a chlordiazepoxide hydrochloride crude product; and (2) adding the chlordiazepoxide hydrochloride crude product into the micromolecule linear-chain aliphatic ketone, and stirring to raise the temperature to a reaction temperature, performing warm-keeping reaction, filtering while hot, washing, filtering thoroughly and drying, so as to obtain chlordiazepoxide hydrochloride. Compared with a conventional preparation method, the method possesses the advantages of being mild in reaction conditions, simple production technology, easily controllable in process, high in reaction yield, convenient for mother liquor recovery, substantially reduced in cost and suitable for industrialized production, and using a single solvent. The prepared chlordiazepoxide hydrochloride possesses the advantages of small hygroscopicity, high purity and good stability.