Study Of Cyclic Synthesis Of Bis(Trichloromethyl) Carbonate

Bis?trichloromethyl?carbonate?BTC?,also named as solid phosgene and triphosgene,is an important green synthetic intermediate in medicine,pesticide,dye,polymer materials,and organic synthesis.It has been widely used as a substitute for phosgene and diphosgene in chlorination,acylation,cyclization,and dehydration reactions.This paper studied the cyclic synthesis of triphosgene from methanol and chlorine gas by using BTC as an initiator.The process involves two steps:?1?preparation of dimethyl carbonate by the methanolysis of triphosgene;?2?preparation of triphosgene by the chlorination of dimethyl carbonate.Eventually,only methanol and chlorine are consumed for the production of triphosgene.In the synthesis of dimethyl carbonate from methanol and triphosgene,the influence of N₂,temperature,triethylamine,Lewis acids have been studied and the optimized reaction conditions have been developed,BTC:CH₃OH?mol?=1:30,6 mol%AlCl₃,35?.After reacting 18 h,the yield reached 88.4%.In the synthesis of triphosgene,with suitable light source and special chlorination reactor,chlorination of dimethyl carbonate occurred without any solvent and chemical initiator,which afforded high purity triphosgene successfully.Further efforts were also made to explore direct chlorination of the mixture of methanol and triphosgene.The whole reaction system was quite complex and only a small amount of triphosgene was produced with a lot of by-products.