PREPARATION OF STEREOISOMER MIXTURE OF HIGHER ACTIVE PHENYLACETIC ESTER DERIVATIVE

摘要

PURPOSE:To obtain a phenvalerate of Y form having improved insecticidal effect or one rich in Y form, by precipitating II tyype crytal of Y form different from a well-known crystal from a solution of a racemic modification of phenvalerate. CONSTITUTION:A solution of a racemic modification of phenvalerate: alpha-cyano- 3-phenoxybenzyl 2-(4-chlorophenyl)-isovalerate, is heated preferably at >=40 deg.C once, II type crystal of Y form different from a well-known Y form crystal is seeded in the solution so that II type crytal is precipitated, to give Y form phenvalerate or phenvalerate rich in Y form. II type crystal is recrystallized, the prepared crystal together with mother liquor is blended with a solution of a racemic modification without being isolated, to precipitate preferably II type crystal. II type crystal has the following properties. Lattice system: monoclinic system. Lattice constant: a=11.90A, b=5.60A, c=32.58A, beta=93.0 deg.. Space group: P21/c. Density: 1.28g/cm<3>. Molecular number per unit lattice: 4.