Abstract: Fifty-two N-methyl substituted phenyl carbamates had been synthesized by reaction of methyl aminocarbonyl chloride (NCC) with appropriate phenols in water-phase. Biological experiments on housefly Musca domestica showed that among the monoalkyl substituted phenyl carbamates, the toxicity of meta-alkyl derivative was higher than those of the ortho- and para-alkyl derivatives, and the toxicity of N-methyl-3-isopropyl phenyl carbamate was the highest with the LD₅₀ of 0.4511 μg/housefly. For monohalide derivatives, the toxicity of ortho-chloro was higher than those of meta- and para-chloro derivatives. The methylthio and ethylthio substituted derivatives showed high toxicity. The toxicities of the meta-alkyl substituted phenyl carbamates were increased in some degree with the enhancement of the molecular weight of those compounds in the order isopropyl> ethyl>methyl>H on the phenyl ring.

Key words: synthesis, carbamate, chemical structure, biological activity