Experimental and computational determination of Brønsted coefficients for equilibrium transfer of the<i>O</i>,<i>O</i>-dimethyl phosphorothioyl group between oxyanion nucleophiles
作者:David R. Edwards、Christopher I. Maxwell、Robert W. Harkness、Alexei A. Neverov、Nicholas J. Mosey、R. Stan Brown
DOI:10.1002/poc.1903
日期:2012.3
phosphorothioate, pKaHOAr of 7.14) is linear over the entire range of phenoxides employed (5.53 ≤ pKaNu ≤ 12.38), the reaction for phenoxide nucleophiles displacing phenoxide leaving groups is probably concerted. The obtained data allow one to calculate, for a symmetrical transition state involving 2,4,5‐trichlorophenoxide as a nucleophile and leaving group, an approximately 60% P–OAr cleavage and about 40% P–Nuc
提出了在25°C下水和甲醇中的氧阴离子亲核体之间O,O-二甲基硫代硫酰基之间的平衡转移的βEq值的实验确定。两种溶剂中各自的βEq值在实验上相同,分别为-1.45±0.08和-1.39±0.12。根据观察发现,水中苯酚与底物1d(4-硝基苯基二硫代磷酸二甲酯,p K a HOAr为7.14)的亲核反应的布朗斯台德相关性在所用苯酚的整个范围内(5.53≤p K a Nu ≤12.38),酚盐亲核试剂取代酚盐离去基团的反应可能是一致的。对于涉及2,4,5-三氯苯酚作为亲核体和离去基团的对称过渡态,获得的数据可以计算出大约60%的P–OAr裂解和大约40%的P–Nuc键形成。提出了一种计算方法,用于快速预测此类过程在水和甲醇中的βEq值,并将结果与文献中的已知值进行比较。版权所有©2011 John Wiley&Sons,Ltd.