Linear free energy study of ring-substituted aniline ozonation for developing treatment of aniline-based pesticide wastes

The relative rate constants for the reaction of ozone were determined for s everal substituted anilines in aqueous solutions at pH 6.5 and 1.5. At pH 6 .5, with the exception of m- and p-nitroaniline, the rate constants obey Ha mmett's equation: log(k(X)/k(H)) = rho psi. The departure of m- and p-nitro aniline may be explained by direct conjugation of the reaction center. The commonly used sigma (-)(p) value of 1.27, which extends the range of applic ability of the Hammett equation, was insufficient to account for the conjug ation effects on ozonation of p-nitroaniline; rho = -1.48 (R = 0.973). Use of amine group atomic charge determinations significantly improved correlat ions: (k(X)/k(H)) = 48.7 delta - 18.2 (R = 0.996). A linear plot of Hammett constants versus relative rate data at pH 1.5 showed poor correlation: rho = 0.72 (R = 0.572). Poor correlation was similarly observed for amine grou p atomic charge determinations, suggesting varied reaction mechanisms.