Dehydrochlorination of 1,1,1,3,3-Pentachlopropane promoted by fluoride

The dehydrochlorination of 1,1,1,3,3-pentachloropropane (HCC-240fa) with alkali metal halide in amide to produce tetrachloropropene isomers was taken into investigation. Studies found that E-1,3,3,3-tetrachloropropene (HCO-1230zd(E)), Z-1,3,3,3-tetrachloropropene (HCO-1230zd(Z)) and 1,1,3,3-tetrachloropropene (HCO-1230za) were formed by the selective dehydrochlorination promoted by halide anions, where fluoride had the best reactivity among the four kinds of halide anions. Besides, it was also found when the molecular polarity index (MPI) of the amide was greater than or equal to 14.3 kcal/mol, it was conducive to the dehydrochlorination reaction, and the conversion was close to 100%. Additionally, DFT calculations demonstrated that the selective dehydrochlorination at the 1-position and 2-position of HCC-240fa was easier than that at the 2-position and 3-position, which is consistent with the experimental results.