Mechanistic studies of La3+ and Zn2+-catalyzed methanolysis of O-ethyl O-aryl methylphosphonate esters. An effective solvolytic method for the catalytic destruction of phosphonate CW simulants
作者:Roxanne E. Lewis、Alexei A. Neverov、R. Stan Brown
DOI:10.1039/b511550g
日期:——
the La3+ reaction and ca. 70% in the Zn2+ catalyzed reaction. The catalysis afforded by the metal ions is remarkable, being about 10(6)-fold and 10(8)-fold for poor and good leaving groups, respectively, relative to the background reactions at pH 9.1. Solvent deuterium kinetic isotope studies for two of the substrates promoted by 5:Zn2+(-OCH3) give kH/kD = 1.0 +/- 0.1, consistent with a nucleophilic
研究了由甲醇,La3 +和Zn2 +(-OCH3)(5:Zn2 +(-OCH3))的甲醇盐,La3 +和1,5,9-三氮杂环十二烷配合物促进的6种O-乙基O-芳基甲基膦酸酯(6a-f)的甲醇动力学。模拟化学战(CW)剂,并通过使用布朗斯台德图进行分析。β(Ig)值分别为-0.76,-1.26和-1.06,表明过渡态时P-OAr键显着减弱。对于金属催化的反应,数据与一致的过程一致,在La3 +反应中,P-OAr键的断裂进展至84%左右。70%在Zn2 +催化的反应中。金属离子提供的催化作用显着,相对于pH值为9.1的本底反应,离去基团较好和离去基团分别为约10(6)倍和10(8)倍。由5:Zn2 +(-OCH3)促进的两种底物的溶剂氘动力学同位素研究得出kH / kD = 1.0 +/- 0.1,与亲核机理相符。提出了金属催化反应的统一机制,该机制涉及底物与金属离子的预平衡配位,然后分子内传递配位的甲醇盐。