Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide
作者:Vincent F. DeTuri、Heinz F. Koch、Judith G. Koch、Gerrit Lodder、Masaaki Mishima、Han Zuilhof、Neal M. Abrams、Cecily E. Anders、Justin C. Biffinger、Patrick Han、Adam R. Kurland、Jason M. Nichols、Anne M. Ruminski、Patricia R. Smith、Karen D. Vasey
DOI:10.1002/poc.1057
日期:2006.5
Hydron exchange reaction rates, kexch M−1s−1, using methanolic sodium methoxide are compared with gas-phase acidities, ΔG kcal/mol, for four 9-YPhenylfluorenes-9-iH, seven YC6H4CiH(CF3)2, seven YC6H4CiHClCF3, and C6F5iH. Fourteen of the fluorinated benzylic compounds and pentafluorobenzene result in near unity experimental hydrogen isotope effects that suggest substantial amounts of internal return
将使用甲醇甲醇钠的氢交换反应速率k exch M -1 s -1与 四个9-Y苯基芴-9- i H,七个YC 6 H 4 C i的气相酸度ΔG kcal / mol进行比较。H(CF 3)2,七个YC 6 H 4 C i HClCF 3和C 6 F 5 iH.十四种氟化苄基化合物和五氟苯导致接近统一的实验性氢同位素效应,表明与交换过程相关的大量内部回流。尽管9-苯基芴的反应具有实验上的同位素效应,似乎在价值上是正常的,但它们不服从Swain-Schaad关系。这表明它们以少量的内部收益发生。苄基化合物的活化熵ΔS ‡为+12至+14 eu,与9-Y苯基芴基的活化熵ΔS ‡为-8至-12 eu。该Δ小号‡ 五氟苯反应的〜1 eu介于其他化合物之间。密度泛函计算使用B3LYP / 6-31 + G(d,p)的报告为CH的反应3 ø -(HOCH 3)3为C 6 ˚F 5 H,C 6 H ^ 5