Research Of Preparing Carbaryl By Methyl Carbamyl Chloride

This thesis is focused on the preparation of methyl isocyanate (MIC) by methyl carbamyl chloride (MCC) and the preparation of Carbaryl by MIC. During these two processes carbon tetrachloride was not used as solvent. Fistly, three solvents including toluene, chloroform, and tetrachloroethylene were selected to substitute carbon tetrachloride. Meanwhile three kinds of organic alkalies including triethylamine, N- methyl imidazole, N- butyl imidazole were selected to react with hydrochloric acid, which is produced during the process of decomposing MCC to prepare MIC.When the organic alkali reacted with hydrochloric acid, it will be neutralized to muriate. The method of separing MIC from the muriate was studied fistly. For the solvents of toluene and tetrachloroethylene, pressurized filtration method of separation was used, while for chloroform solvent, the distillation method of separation was used.After the separation method was determined, influence factors of preparing carbaryl by MCC were investigated experimentally. These influencing factos included the droping speed of organic alkali, the amount of organic alkali, the temperature of the decomposition of MCC, the amount of solvent, the sort of organic alkali and so on.Through the study on the influencing factors, the optimum condition had been determined. When toluene is used as solvent, the optimum condition was as follows:MCC:toluene=1:6(mass ratio, m/m); organic alkali:toluene =1:1(m/m); 1-naphthol:MCC:organic alkali=1:1:0.98(mol/mol/mol); The decomposition temperature of MCC was set to 50℃; The synthesis temperature of carbaryl with MIC and 1- naphthol was 108℃and the reaction time was 2 hours.When chloroform is used as solvent, the optimum condition was as follows:MCC:toluene =1:5(m/m); organic alkali:toluene =1:1(m/m); 1- naphthol: MCC:organic alkali =1:1:0.98(mol/mol/mol); The decomposing temperature of MCC was set to 50℃; The synthesis temperature of carbaryl with MIC and 1- naphthol was 58℃and the reaction time was 4 hours.Under the optimum condition, no matter the solvent was toluene or chloroform, the yield of carbaryl was the highest when the organic alkali was N- butyl imidazole. The yield of carbaryl was the lowest when the organic alkali was N- methyl imidazole. When the organic alkali was triethylamine, the yield of carbaryl was close to N- butyl imidazole. For a specified alkali, the yield of carbaryl in chloroform solvent was obviously higher than that in toluene solvent.When the organic alkali was N- butyl imidazole, the BASIL process could be applied in the reaction of decomposing MCC to prepare MIC. The used N- butyl imidazole can be reclaimed using sodium hydroxide, however, the water content in the recycled N-butyl imidazole is relatively high, which may reduce the yield of carbaryl. Pyrolytic process could be used to recover N- butyl imidazole from its hydrochloric salt via decomposing at high temjperature.