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首页> 外文期刊>Journal of Physical Organic Chemistry >Nucleophilicity parameters for strong nucleophiles in dimethyl sulfoxide. A direct alternative to the s(E+N) equation
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Nucleophilicity parameters for strong nucleophiles in dimethyl sulfoxide. A direct alternative to the s(E+N) equation

机译：二甲基亚砜中强亲核试剂的亲核性参数。 s（E + N）方程的直接替代

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摘要

A scale of nucleophilicity (N?) for relatively strong nucleophiles (e.g. carbanions and amines), spanning over 5 orders of magnitude was constructed directly from experimental rate constants for reactions of 34 nucleophiles with a benzhydrylium cation, (lil)_2CH~+ (log k=N? in dimethyl sulfoxide at 20°C). The equation log k=(E?+s_EN? +c), where E? is an electrophilicity parameter, s_E is a Swain-Scott type of response parameter (to variation in nucleophilicity) for the electrophile, and c is a residuals term, is used to correlate second order rate constants for reactions of nucleophiles with other benzhydrylium cations, quinone methides (QM) and Michael-acceptor electrophiles. Contrary to published claims (Mayr et al. Angew Chem. Int. Ed. 2002, 41, 92, and later work), sE increases as the reactivity of the QM decreases. The N? scale was extended a further 3 orders of magnitude by an extrapolation involving a QM electrophile. In contrast, published procedures involve over 40 reference electrophiles and over 100 adjustable parameters obtained from the equation log k=sN(E+N), where k is the rate constant, and sN is a nucleophile parameter. Values of N-N? in DMSO increase by 8 log units, as the reactivity of the nucleophile increases, because N is a floating scale whereas N? is a fixed scale.
机译：直接从34个亲核试剂与苯甲铵阳离子（lil）_2CH〜+（log在20℃的二甲基亚砜中，k ＝ N 2）。公式log k =（E？+ s_EN？+ c），其中E？是亲电参数，s_E是亲电试剂的Swain-Scott型响应参数（对亲核试剂的变化），c是残差项，用于将亲核试剂与其他苯甲酸铵阳离子，醌的反应的二阶速率常数相关联甲基化物（QM）和迈克尔受体亲电试剂。与已发表的权利要求相反（Mayr等人，Angew Chem.Int.Ed.2002，41，92，和以后的工作），随着QM的反应性降低，sE增加。然后？通过涉及QM亲电试剂的外推法，可扩展性进一步扩展了3个数量级。相反，已公开的程序涉及40多个参考亲电试剂和100多个从等式log k = sN（E + N）获得的可调参数，其中k是速率常数，sN是亲核参数。 N-N的值？由于亲核试剂的反应性增加，DMSO中的N 2 +增加8个log单位，因为N是一个浮标，而N 2是一个浮标。是固定比例。

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