Sevvel R, Rajagopal S, Srinivasan C, Alhaji NI, Chellamani A
Department of Materials Science and School of Chemistry, Madurai Kamaraj University, Madurai - 625 021, India, and Department of Chemistry, Manonmaniam Sundaranar University, Tirunelveli - 627 012, India.
J Org Chem. 2000 Jun 2;65(11):3334-40. doi: 10.1021/jo9916380.
The selective oxidation of organic sulfides to sulfoxides by oxo(salen)chromium(V) complexes in acetonitrile is overall second-order, first-order each in the oxidant and the substrate. The rate constant, k(2), values of several para-substituted phenyl methyl sulfides correlate linearly with Hammett sigma constants and the rho values are in the range of -1.3 to -2.7 with different substituted oxo(salen)chromium(V) complexes. The reactivity of different alkyl sulfides is in accordance with Taft's steric substituent constant, E(S). A mechanism involving direct oxygen atom transfer from the oxidant to the substrate rather than electron transfer is envisaged. Correlation analyses show the presence of an inverse relationship between reactivity and selectivity in the reaction of various sulfides with a given oxo(salen)chromium(V) complex and vice versa. Mathematical treatment of the results shows that this redox system falls under strong reactivity-selectivity principle (RSP).
在乙腈中，氧代（萨伦）铬（V）配合物将有机硫化物选择性氧化为亚砜的反应总体为二级反应，氧化 剂和底物各为一级反应。几种对取代苯基甲基硫化物的速率常数k(2)值与哈米特σ常数呈线性相关，不同取代的氧代（萨伦）铬（V）配合物的ρ值在-1.3至-2.7范围内。不同烷基硫化物的反应活性与塔夫特立体取代常数E(S)一致。设想了一种涉及从氧化剂直接向底物转移氧原子而非电子转移的机理。相关分析表明，各种硫化物与给定的氧代（萨伦）铬（V）配合物反应时，反应活性和选择性之间存在反比关系，反之亦然。结果的数学处理表明，该氧化还原体系符合强反应活性-选择性原理（RSP）。
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