ORGANOPHOSPHORUS ESTER DERIVATIVES, PROCESS FOR THEIR PREPARATION, AND INSECTICIDES CONTAINING THEM AS EFFECTIVE INGREDIENTS

摘要

Novel organophosphorus ester derivatives of the formula (I) wherein R₁ represents alkyl, R₂ represents alkyl or thioalkyl, R₃, R₄, and R. may be the same or different and each represents hydrogen, halogen, alkylothio, nitro, cyano, alkyl, alkylsulfinyl, or trifluoromethyl, and X represents oxygen or sulfur, process for their preparation, and insecticides containing them as effective ingredients.