Kinetic Study on Alkaline Hydrolysis of Y-substituted Phenyl X-substituted Benzenesulfonates: Effects of Changing Nucleophile from Azide to Hydroxide Ion on Reactivity and Transition-State Structure
作者:Ji-Hyun Moon、Min-Young Kim、So-Yeop Han、Ik-Hwan Um
DOI:10.1002/bkcs.10297
日期:2015.6
Second‐order rate constants () for alkaline hydrolysis of 2,4‐dinitrophenyl X‐substituted benzenesulfonates (1a–1f) and Y‐substituted phenyl 4‐nitrobezenesulfonates (2a–2g) have been measured spectrophotometrically. Comparison of with the values reported previously for the corresponding reactions with has revealed that OH is only 103‐fold more reactive than , although the former is 11 pK a units
用分光光度法测量了2,4-二硝基苯基X-取代的苯磺酸盐(1a-1f)和Y-取代的苯基4-硝基苯磺酸盐(2a-2g)的碱解二级速率常数()。比较与所述值之前为相应的反应报道显示,OH 只有10 3倍比更具反应性,虽然前者是11个P ķ 一个单位比后者更碱性。汤川-津野情节用于的反应中1A-1F导致具有优异的线性相关ρ X = 2.09和- [R= 0.41。用于反应中的布朗斯台德型情节2A-2G是线性与β LG = -0.51,这是典型的反应报告通过协调一致机理进行。汤川-津野情节用于的反应中2A-2G显示出优异的线性度ρ Ŷ = 1.85和- [R = 0.25,这表明局部负电荷开发上离去基团的在过渡态O原子。因此,已得出结论认为1a-1f和2a-2g的碱性水解是通过协同机制进行的。所述的比较ρ X和β LG用于与反应值 离子表明,与氢氧根离子相比,与氢氧根离子的反应通过更紧密的过渡态结构进行。