Spectral and Mechanistic Investigation of Oxidative Decarboxylation of Phenylsulfinylacetic Acid by Cr(VI)
作者:Perumal Subramaniam、Natesan Thamil Selvi、Soundarapandian Sugirtha Devi
DOI:10.5012/jkcs.2014.58.1.17
日期:2014.2.20
acid (PSAA) by Cr(VI) in 20% acetonitrile − 80% water (v/v) medium follows overall second order kinetics, first order each with respect to (PSAA) and (Cr(VI)) at constant (H + ) and ionic strength. The reaction is acid catalysed, the order with respect to (H + ) is unity and the active oxidizing species is found to be HCrO3 + . The reaction mechanism involves the rate determining nucleophilic attack
在20%乙腈-80%水(v / v)介质中,Cr(VI)对苯亚磺酰基乙酸(PSAA)的氧化脱羧反应遵循总体二级动力学,分别涉及(PSAA)和(Cr(VI))的一级动力学。在恒定的(H +)和离子强度下。该反应是酸催化的,相对于(H +)的顺序是单一的,并且发现活性氧化物质是HCrO3 +。反应机理涉及速率确定PSAA的硫原子对HCrO3 +的铬形成亲核离子中间体的亲核攻击。然后中间体经历α,β裂解,从而释放出CO2。发现该反应的产物是甲基苯基砜。取代基效应的作用表明,在间位和对位含有电子释放基团的PSAA加快了反应速率,而电子吸收基团则阻碍了该速率。发现log k2和Hammettσ常数之间存在极好的相关性,而反应常数为负值。ρ值随温度升高而降低,这表明在取代PSAA的情况下具有高反应活性和低选择性。