Effect of Meta and Para Substituents on the Stannous Chloride Reduction of Nitrobenzenes in Aqueous Ethanol

Article abstract of DOI:10.1021/jo00163a018

The rate of reduction of 24 meta- and para-substituted nitrobenzenes with SnCl2 catalyzed by HCl in ethanol-water (90 : 10 v/v) at 30 degC has been measured iodometrically.The rate is expressed as υ = k_st^0.5, suggesting that the sole active reducing species is SnCl3^- and the dissociation of HCl is very small.The effect of meta and para substituents in which the solvation of the substituent is taken into account was examined with the Hammett equation, which gave a ρ value of 2.1 +/- 0.1.Yukawa-Tsuno and Taft equations, in which resonance and inductive effects are separated, are also discussed.