Dissection of Nucleophilic and General Base Roles for the Reaction of Phosphate with <i>p</i>-Nitrophenyl Thiolacetate, <i>p</i>-Nitrophenyl Thiolformate, and Phenyl Thiolacetate
作者:Manjinder S. Gill、Alexei A. Neverov、R. S. Brown
DOI:10.1021/jo970904b
日期:1997.10.1
well-known to catalyze the decomposition of various active acyl compounds. This study was undertaken to determine the extent to which it acts as a nucleophile and general base toward some activated esters and thiolesters. Thus, the hydrolyses of p-nitrophenyl acetate (3a), p-nitrophenyl thiolacetate (3b), phenyl acetate (4a), phenyl thiolacetate (4b), and p-nitrophenyl thiolformate (5) have been studied
众所周知,磷酸盐缓冲液可催化各种活性酰基化合物的分解。进行这项研究是为了确定它作为亲核试剂和对某些活化的酯和硫酯的一般碱的作用程度。因此,已经研究了在磷酸盐水溶液中对对硝基苯乙酸酯(3a),对硝基苯硫基乙酸酯(3b),乙酸苯酯(4a),苯硫基乙酸酯(4b)和对硝基苯硫基甲酸酯(5)的水解。= 1.0(K(2)SO(4))。磷酸单阴离子和双阴离子都可与硫酯3b,4b和5发生反应。对于3b,双阴离子的反应显示出1.00 +/- 0.11的溶剂动力学同位素效应(SKIE),而单阴离子的反应动力学同位素效应为2.13 +/- 1.1 。对于磷酸二阴离子与5的反应,SKIE为0.8 +/- 0.2,而对于单阴离子在pH 3.05下的SKIE约为1.5。磷酸二阴离子与每种硫羟乙酸盐及其氧类似物以相当的速率反应:甲酰基与乙酰基硫酯的比例为5:3b,对磷酸二阴离子为685。(1)H(2)中3b水解混合物的H