作者:Bernard Denegri、Olga Kronja
DOI:10.1021/jo900852u
日期:2009.8.21
A series of X,Y-substituted benzhydryl heptafluorobutyrates (1−6-HFB) and trifluoroacetates (1−6-TFA) were subjected to solvolysis in various methanol/water, ethanol/water, and acetone/water mixtures at 25 °C. The LFER equation log k = sf(Ef + Nf) was used to derive the nucleofuge-specific parameters (Nf and sf) for SN1-type reaction. In comparison with TFA, the HFB leaving group is a better nucleofuge
一系列X,Y的取代的二苯甲基heptafluorobutyrates(1 - 6 -HFB)和三氟乙酸盐(1 - 6 -TFA)在25经受溶剂解在不同甲醇/水,乙醇/水和丙酮/水混合物℃。LFER方程log k = s f(E f + N f)用于得出S N 1型反应的核试剂特定参数(N f和s f)。与TFA相比,HFB离去基团是N f小于0.5单位的更好的核试剂。除非吸电子基团连接在芳环上,否则X,Y取代的三氟乙酸二氢苯酯通过S N 1反应溶剂化。在这种情况下,底物溶剂分解比预期用于S更快Ñ因为在机构的变化的1路线。X,Y取代的二苯甲基heptafluorobutyrates检查这里(Ë ˚F ≥-7.7)溶剂分解根据在S Ñ 1通路。在HFB和TFA的各种溶剂中,几乎平行的log k vs. E f线,以及相应的斜率参数(s f(范围在0.91和0.83之间),表示早期TS,且电荷分离程度适中。均以PCM-B3LYP