Spectral and Mechanistic Investigation of Oxidative Decarboxylation of Phenylsulfinylacetic Acid by Cr(VI)

Journal of the Korean Chemical Society

Soundarapandian Sugirtha Devi¹  Natesan Thamil Selvi¹  Perumal Subramaniam¹ 

关键词: Phenylsulfinylacetic acid;    Oxidative decarboxylation;    Nucleophilic attack of sulfur;    Substituent effect;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

The oxidative decarboxylation of phenylsulfinylacetic 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 of sulfur atom of PSAA on chromium of HCrO3 + forming a sulfonium ion intermediate. The intermediate then undergoes ¥á,¥â-cleavage leading to the liberation of CO2. The product of the reaction is found to be methyl phenyl sulfone. The operation of substituent effect shows that PSAA containing electron-releasing groups in the meta- and para-positions accelerate the reaction rate while electron withdrawing groups retard the rate. An excellent correlation is found to exist between log k2 and Hammett ¥ò constants with a negative value of reaction constant. The ¥ñ value decreases with increase in temperature evidencing the high reactivity and low selectivity in the case of substituted PSAAs.

【 授权许可】

Unknown