Olah G A, Rasul G, Burrichter A, Prakash G K
Donald P. and Katherine B. Loker Hydrocarbon Research Institute, University of Southern California, University Park, Los Angeles, CA 90089-1661, USA.
Proc Natl Acad Sci U S A. 1998 Apr 14;95(8):4099-101. doi: 10.1073/pnas.95.8.4099.
Attempted hydrogen-deuterium exchange of trimethyloxonium ion, (CH3)3O+ with excess of 1:1 (2)HF/SbF5 superacid at -30 degreesC over a period of 30 days showed no exchange. Theoretical calculations at the MP2/6-31G** level are in accord with the lack of hydrogen-deuterium exchange in the methyl group of the (CH3)3O+ cation as protonation (protosolvation) prefers the oxygen lone pair of electrons, instead of a C---H bond. Methylation of aromatics with the (CH3)3O+CF3SO3- in CF3SO3H and 2CF3SO3H:B(O3SCF3)3 was also studied. Whereas in triflic acid no alkylation was observed, in triflatoboric acid, a powerful superacid, alkylation takes place, indicating protolytic activation of the trimethyloxonium ion.
在-30℃下，将三甲基氧鎓离子(CH3)3O+与过量的1:1(2)HF/SbF5超强酸反应30天，未观察到氢-氘交换。在MP2/6-31G**水平上的理论计算结果与(CH3)3O+阳离子甲基中不存在氢-氘交换一致，因为质子化（质子溶剂化）更倾向于氧的孤对电子，而不是碳氢键。还研究了在CF3SO3H和2CF3SO3H:B(O3SCF3)3中用(CH3)3O+CF3SO3-对芳烃进行甲基化反应。在三氟甲磺酸中未观察到烷基化反应，而在一种强超强酸三氟甲磺酸硼酸中则发生了烷基化反应，这表明三甲基氧鎓离子发生了质子解离活化。
