nucleophile carbon, the nucleophile nitrogen, and the chlorine leaving group kinetic isotope effects for the SN2 reaction between cyanide ion and ethyl chloride were determined in the very slightly polar solvent THF at 30 °C. A comparison of these KIEs with those reported earlier for the same reaction in the polar solvent DMSO shows that the transition state in THF is only slightly tighter with very slightly
在极弱极性的溶剂中测定了
氰化物离子与
氯乙烷之间的S N 2反应的仲α-和β-
氘,α-碳,亲核碳,亲核氮和
氯离去基团的动力学同位素效应THF在30°C下。这些KIES与那些的比较此前报道在极性溶剂
DMSO节目相同的反应,在THF过渡态仅与非常稍短NC-C略微更紧α和C α-Cl键。过渡态结构的这种微小变化不能解释先前通过分别解释实验性KIE和气相计算而提出的不同过渡结构。因此,两种方法所建议的不同过渡态似乎不太可能是由于理论计算中缺乏适当的溶剂模型。先前有人预测,S的过渡状态Ñ 2个反应,其中所述亲核试剂和离去基团具有相同的电荷将通过在溶剂中的变化的影响。1实验性KIE支持此观点。