substituted phenolate anions with m-nitrophenyl, p-nitrophenyl, and 3,4-dinitrophenyl formates follow nonlinear BrOnsted-type correlations that might be taken as evidence for a change in the rate-limiting step of a reaction that proceeds through a tetrahedral addition intermediate. However, the correlation actually represents two different BrOnsted lines that are defined by meta- and para-substituted phenolate
取代
苯酚阴离子与间
硝基苯基、对
硝基苯基和 3,4-
二硝基苯基
甲酸酯的反应遵循非线性 BrOnsted 型相关性,可以作为反应的限速步骤发生变化的证据。四面体加成中间体。然而,相关性实际上代表了两个不同的布朗斯特线,它们由间位和对位取代的
苯酚阴离子以及间位和对位取代的
邻氯苯酚阴离子定义。在 ΔpK=0 时,在每一类 BrOnsted 相关性中攻击和离开
酚酸阴离子的 BrOnsted 斜率没有可检测的变化,这支持了乙酰基和甲酰基转移反应的协调机制