METHOD FOR PRODUCING PHOSPHITE COMPOUND CRYSTAL

PROBLEM TO BE SOLVED: To produce the crystals of a phosphorous ester compound of formula (I) in high recovery, when two or more batches of the phosphorous ester compound are continuously crystallized by a batch type method. SOLUTION: This method for producing the phosphorous ester compound crystals comprises the following first to sixth processes. The first process: cooling and crystallizing a liquid containing the first batch compound of formula (I) and a crystallizing solvent by a batch type method. The second process: filtering the produced slurry containing the crystals of the compound of formula (I) and the crystallizing solvent to obtain the crude wet cake. The third process: washing the crude wet cake with a washing solvent to obtain the purified wet cake and the washing liquid of the first bath. The fourth process: : cooling and crystallizing a liquid containing the second batch compound of formula (I), a crystallizing solvent, and the liquid containing the washing liquid of the first batch by a batch method. The fifth process: filtering the produced slurry containing the crystals of the compound of formula (I), the crystallizing solvent, and the washing liquid of the first batch to obtain the crude wet cake. The sixth process: washing the crude wet cake with a washing solvent to obtain the purified wet cake and the washing liquid of the second bath. COPYRIGHT: (C)2005,JPO&NCIPI