KINETICS OF NUCLEOPHILIC SUBSTITUTION IN 1,1-DIARYL-2-FLUOROETHYLENES

Reactions of 1,1-diphenyl-, 1,1-di-(p-tolyl)-, and 1,1-di-(p-chlorophenyl)- 2-fluoroethylenes with toluene-p-thiolate in dimethylformamide were kinetically studied at temperatures in the range 20-70°. Substitutions are free from side reactions and have rates which are strongly dependent on substituents on the phenyl rings (p = 4.3 at 24°). Measured rate coefficients are larger than those of the corresponding diarylchloroethylenes in the same reaction. This leaving-group effect is discussed.