Competitive behavior of nitrogen based axial ligands in the oxovanadium(IV)-salen catalyzed sulfoxidation of phenylmercaptoacetic acid
作者:C. Kavitha、P. Subramaniam
DOI:10.1016/j.poly.2020.114712
日期:2020.10
Abstract The sulfoxidation of twelve phenylmercaptoacetic acids (PMAA) by H2O2 catalyzed by three oxovanadium(IV)-salen complexes, having varied substituents on PMAA and salen with regard to their position, size and inductive effect, has been performed spectrophotometrically in 100% acetonitrile medium. Three nitrogen bases (NB), pyridine (Py), imidazole (ImH) and 1-methylimidazole (MeIm), were used
摘要在100%乙腈介质中用分光光度法进行了分光光度法测定了三种氧杂钒-salen配合物对PMAA和Salen的取代,位置,大小和诱导效果的影响,通过H2O2催化H2O2对十二种苯巯基乙酸(PMAA)进行硫氧化。 。三个氮碱(NB),吡啶(Py),咪唑(ImH)和1-甲基咪唑(MeIm)用作轴向配体。已经发现,硫氧化的速率不仅受PMAA和salen上的取代基调节,而且还因添加氮碱而变化。在不同的氮碱中发现的观察到的阻滞顺序为ImH> MeIm> Py。反应速率随NB轴向配体浓度的增加而降低。结合力强的ImH表现出最低的反应性。氢过氧钒(V)-salen已被提议作为唯一的活性氧化物质。详细的机理研究表明,在存在氮碱的情况下,低速率常数值是由于活性物质形成过程中NB与H2O2和PMAA的竞争以及PMAA与活性物质的配位而存在的。PMAA上的给电子取代基和吸电子取代基都显着阻碍了硫氧化速度。速率常