| Abstract
| - The relative rate constants for the reaction of ozone were determined for several substituted anilinesin aqueous solutions at pH 6.5 and 1.5. At pH 6.5, with the exception of m- and p-nitroaniline, therate constants obey Hammett's equation: log(kX/kH) = ρσ. The departure of m- and p-nitroanilinemay be explained by direct conjugation of the reaction center. The commonly used σp- value of1.27, which extends the range of applicability of the Hammett equation, was insufficient to accountfor the conjugation effects on ozonation of p-nitroaniline; ρ = −1.48 (R = 0.973). Use of amine groupatomic charge determinations significantly improved correlations: (kX/kH) = 48.7δ − 18.2 (R = 0.996).A linear plot of Hammett constants versus relative rate data at pH 1.5 showed poor correlation: ρ= 0.72 (R = 0.572). Poor correlation was similarly observed for amine group atomic chargedeterminations, suggesting varied reaction mechanisms. Keywords: Hammett's equation; Hammett's constant; amine; agrochemicals; nitroaniline; haloaniline; alkylaniline; pesticide waste
|
