Catalysis of decarboxylation by an adjacent negative charge: a theoretical approach.
Catalysis of decarboxylation by an adjacent negative charge: a theoretical approach.
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相邻负电荷催化脱羧：一种理论方法。
DOI：
10.1016/s0045-2068(03)00028-2
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发表时间：
2003
影响因子：
5.1
通讯作者：
Wu,Weiming
中科院分区：
文献类型：
--
作者：
Tran,NgocLien;Colvin,MichaelE;Gronert,Scott;Wu,Weiming
我们计算了在不同介电常数的介质中，通过底物羧酸盐和相邻负电荷之间的电荷斥力可以实现的脱羧化反应的速率加速。结果表明，完全负电荷或周围的部分负电荷也有同样的效果。结果表明，附近负电荷的存在可以大大加快脱羧基的速度。例如，在介电常数从5.62到20.7的介质中，通过将负电荷放置在远离底物羧酸盐基团的3.77？处，可以实现108倍的速率加速。然而，pK在两个接近的羧酸基上的扰动可能会限制催化的程度。还应该注意的是，当介电常数从5.62变化到20.7时，催化程度变化不大。
We have calculated the rate acceleration in decarboxylation reactions that can be accomplished by charge–charge repulsion between the substrate carboxylate and an adjacent negative charge in media of various dielectric constants. It has been shown that a full negative charge or surrounding partial negative charges will have the same effect. It is concluded that the rate of decarboxylation could be greatly accelerated by the presence of a negative charge nearby. For example, in media with dielectric constants from 5.62 to 20.7, a 108-fold rate acceleration could be achieved by a negative charge placed 3.77Å away from the substrate carboxylate group. However, pKaperturbation on two carboxylate groups at close proximity may limit the extent of catalysis. It should also be noted that the extent of catalysis does not change much when the dielectric constant varies from 5.62 to 20.7.