Study On Synthesis Of Anilofos

Anilofos is an organic phosphorus herbicide invented by Hoechst of West Germany in the late 1970s.Its chemical name is S-[2-[(4-chlorophenyl)(1-methylethyl)amino]-2-oxoethyl]O,O-dimethyl ester,which is synthesized from N-(4-Chlorophenyl)-N-(1-methylethyl)carbamic chloride and O,O-dimethyl dithiophosphoric acid or its salt.In this paper,the intermediate N-(4-Chloropheny l)-N-(1-methylethyl)carbamic chloride was synthesized by using p-chloroaniline and 2-bromopropane as starting materials,and ammonium 0,0-dimethyl dithiophosphate using phosphorus pentasulfide and methanol.Then the anilofos was formed by using these two intermediates,and reaction conditions were optimized.N-isopropyl-p-chloroaniline was synthesized by using p-chloroaniline and 2-bromopropane as raw materials.The influence factors of the reaction were studied and the products were characterized by 1H-NMR.Under the optimum conditions,the yield of product could reach 95%and the purity 96.8%.N-isopropyl-p-chloroaniline was then reacted with chloroacetyl chloride to give N-(4-Chlorophenyl)-N-(1-methylethyl)carbamic chloride.This reaction is easy to be carried out,so the yield and purity of product was up to 99%and 98%respectively under the optimum conditions.O,O-dimethyl dithiophosphoric acid was synthesized from diphosphorus pentasulfide and methanol,and then ammonia was added to the reaction system to prepare ammonium O,O-dimethyl dithiophosphate.The key factors affecting the reaction such as solvent,molar ratio,temperature and catalyst were discussed to optimized reaction conditions,under which the yield of the target product was75.3%,and the purity was 99%.After the preparation of two important intermediates,condensation reaction was carried out.The excellent yield and purity could be obtained using n-hexane as solvent,which could be up to 90%and 97%respectively under the optimum conditions.Using n-hexane as solvent is better than using toluene and acetone,which were used in the traditional process,due to can the low cost,no toxicity of toluene and high yield and purity.