Reactions of 1,1-diaryl-2-halogenoethylenes with sodium ethoxide. Part V. Reactivity of pp′-dinitro-derivatives

Abstract

2-Chloro- and 2-bromo-1,1-di(-p-nitrophenyl)ethylenes were prepared, and nucleophilic displacement of halide ions by ethoxide ion was kinetically studied in the range 20–50°. α-Elimination did not interfere. Rates of second-order substitution are ca. 10⁶ times larger than for 2-halogeno-1,1-diphenylethylenes. Kinetic data referring to H, Me, MeO, and NO₂ as p- and/or p′-substituents can be correlated with values of Σσ or Σσ°. A molecular orbital calculation is presented that gives π-electron contributions to the activation energy in good correlation with experimental free energies of activation.