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首页> 外文期刊>Chemistry: A European journal >Activating water: Important effects of non-leaving groups on the hydrolysis of phosphate triesters
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Activating water: Important effects of non-leaving groups on the hydrolysis of phosphate triesters

机译：活化水：非离去基团对磷酸三酯水解的重要作用

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摘要

The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator") groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both β _(LG) and β _(NLG). Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity.
机译：磷酸三-2-吡啶基磷酸酯（TPP）的高自发水解率是由非离去（“旁观者”）基团对P-OAr裂解的活化作用解释的，而不是由分子内催化作用解释的。先前有关磷酸盐转移反应的研究集中在亲核试剂和离去基团对反应活性的贡献上，但是我们的结果表明，非离去基团对磷的影响可能同样重要。对三个系列的磷酸三酯的速率测量结果表明，对于自发水解反应，对非离去基团的敏感性非常重要，尽管对于具有良好亲核试剂的反应则明显较小。三芳基和二烷基芳基三酯之间在对离去基团和非离去基团的敏感性方面存在明显差异，其中反应性更高的三芳基系统显示出较低的β_（LG）和β_（NLG）值。相邻的吡啶氮分子对TPP水解的分子内催化作用微不足道，主要是因为它们的碱度低。

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