Pierpoint A C, Hapeman C J, Torrents A
Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland 20742, USA.
J Agric Food Chem. 2001 Aug;49(8):3827-32. doi: 10.1021/jf010123i.
The relative rate constants for the reaction of ozone were determined for several 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 Hammett's equation: log(k(X)/k(H)) = rho sigma. The departure of m- and p-nitroaniline may be explained by direct conjugation of the reaction center. The commonly used sigma(p)(-) value of 1.27, which extends the range of applicability of the Hammett equation, was insufficient to account for the conjugation effects on ozonation of p-nitroaniline; rho = -1.48 (R = 0.973). Use of amine group atomic charge determinations significantly improved correlations: (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 group atomic charge determinations, suggesting varied reaction mechanisms.
在pH值为6.5和1.5的水溶液中，测定了几种取代苯胺与臭氧反应的相对速率常数。在pH值为6.5时，除间硝基苯胺和对硝基苯胺外，速率常数符合哈米特方程：log(k(X)/k(H)) = ρσ。间硝基苯胺和对硝基苯胺的偏差可以通过反应中心的直接共轭来解释。常用的σ(p)(-)值为1.27，虽然扩展了哈米特方程的适用范围，但不足以解释共轭对对硝基苯胺臭氧化的影响；ρ = -1.48（R = 0.973）。使用胺基原子电荷测定法可显著改善相关性：(k(X)/k(H)) = 48.7δ - 18.2（R = 0.996）。在pH值为1.5时，哈米特常数与相对速率数据的线性图显示相关性较差：ρ = 0.72（R = 0.572）。对于胺基原子电荷测定，同样观察到相关性较差，这表明反应机制存在差异。
