A mechanistic study of the alkaline hydrolysis of diaryl sulfate diesters.
A mechanistic study of the alkaline hydrolysis of diaryl sulfate diesters.
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DOI：
10.1021/jo0488309
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
Jarod M. Younker;A. Hengge
中科院分区：
文献类型：
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作者：
Jarod M. Younker;A. Hengge
几乎所有已报道的硫酸二酯反应研究都是针对二烷基或烷基芳基二酯，它们通过碳-氧键裂变进行反应。通过攻击硫进行的硫酸二酯（RO-SO(2)-OR'）的硫酰基转移反应很少被探索。当两个酯基都是芳基时，水解反应（硫酰基转移到水）通过攻击硫发生。硫酸二芳基二酯的碱性水解被证明遵循 [(-)OH] 的一级动力学，并通过 S-O 键裂变进行，其机制很可能是一致的。 4-氯-3-硝基苯基苯基硫酸盐和 4-硝基苯基苯基硫酸盐的活化参数分别给出以下值： Delta H(++) = 88.0 +/- 0.1 和 84.83 +/- 0.06 kJ mol(-)(1) 和 Delta S(++) = -37 +/- 1 和 -50.2 +/- 0.5 J mol(-)(1)度(-)(1)。分析了水解二阶速率常数对离去基团 pK(a) 的依赖性，得出 -0.7 +/- 0.2 的 beta(lg) 斜率和 0.36 的 Leffler α 参数值。获得了1.0000+/-0.0005的氢氧化物攻击4-硝基苯基苯基硫酸的(15)k动力学同位素效应(KIE)和1.003+/-0.002的(18)k(lg)KIE值。
Nearly all of the reported studies of reactions of sulfate diesters are for dialkyl or alkyl aryl diesters, which undergo reaction by carbon-oxygen bond fission. Sulfuryl transfer reactions of sulfate diesters (RO-SO(2)-OR') proceeding by attack at sulfur have been little explored. When both ester groups are aryl groups the hydrolysis reaction (sulfuryl transfer to water) occurs by way of attack at sulfur. The alkaline hydrolysis of diaryl sulfate diesters was shown to obey first-order kinetics with respect to [(-)OH] and proceed through S-O bond fission, in a mechanism that is most likely concerted. Activation parameters for 4-chloro-3-nitrophenyl phenyl sulfate and 4-nitrophenyl phenyl sulfate gave the following respective values: Delta H(++) = 88.0 +/- 0.1 and 84.83 +/- 0.06 kJ mol(-)(1) and Delta S(++) = -37 +/- 1 and -50.2 +/- 0.5 J mol(-)(1) deg(-)(1). The dependence of the second-order rate constant for hydrolysis on leaving group pK(a) was analyzed giving a beta(lg) slope of -0.7 +/- 0.2 and a Leffler alpha parameter value of 0.36. A (15)k kinetic isotope effect (KIE) for the hydroxide attack on 4-nitrophenyl phenyl sulfate of 1.0000 +/-0.0005 and an (18)k(lg) KIE value of 1.003+/-0.002 were obtained.