PURPOSE: The reaction between a carboxylic acid and phosgen is conducted using a lower aliphatic amide as a catalyst to form a carboxylic chloride, to which a specific solvent is added to precipitate the catalyst dissolving in the mixture, thereby separating high-purity title compound.

CONSTITUTION: The reaction between a carboxylic acid such as isophthalic acid and phosgen is conducted in the presence of a lower aliphatic amide such as dimethylformamide at 0W100°C. To the reaction mixture is added a solvent that lowers the solubility of the catalyst in the reaction mixture such as n-heptane to precipitate the catalyst and the mixture is separated to isolate the high-purity objective compound. The catalyst and solvent can be recycled.

EFFECT: The recovery of the catalyst and recylization of the solvent make the process economic and silmple.

USE: Starting material for thermoplastic resin and fiber, plasticizer, curing agents, intermediate for medicine and agricultural chemicals.