A High-Output, Continuous Selective and Heterogeneous Nitration of p-Difluorobenzene

作者:Yu, Zhiqun; Lv, Yanwen; Yu, Chuanming*; Su, Weike
来源:Organic Process Research & Development, 2013, 17(3): 438-442.
DOI:10.1021/op300350v

摘要

A practical continuous nitration process for 2,5-difluoronitrobenzene via nitration of p-difluorobenzene with fuming nitric acid in 98% yield has been developed. The excellent yield of this liquid/liquid biphasic reaction resulted from the advantages of a continuous flow system. The 2.0 equiv sulfuric acid could be used three times directly with product yields in the range of 96-98%, and further recycling of waste acid could be partly achieved by adjusting the concentration of sulfuric acid. Reaction time could be brought down to 2 min by increasing the reaction temperature and thereby taking advantage of superior mass and heat transfer of this continuous flow system.