2,6-Difluorobenzoyl isocyanate(DFBI)is an important intermediate for the synthesis of ben-zoyl urea pesticides.The synthetic process of DFBI with phosgene is very dangerous,and the cost of preparation of DFBI using oxalyl chloride is high.Bis(trichloromethyl)carbonate(BTC)is a green sub-stitute for the highly toxic phosgene and diphosgene.It not only is low in toxicity,safe and convenient to use,but also has mild reaction conditions,accurate measurement and low price.The DFBI was synthe-sized by the reaction of BTC with 2,6-difluorobenzamide(FBA),and the effect of single factor on the synthesis of DFBI was studied.The experimental results show that the optimal conditions are as follows:Chlorobenzene is used as the solvent,the molar ratio of feeding is n(BTC)∶n(FBA)=1.0∶1.5,BTC is equally fed in two times,and the first stage of cold-phosgenation is reacted at-5 ℃ for 1 h,the second stage of thermal-phosgenation is reacted at 126-128 ℃ for 4 h,and the product yield could reach 86.4％.BTC can be used stably and safely,and the process is easy to industrialize.
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