A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength
作者:Hermann-Josef Frohn、Frank Bailly、Dirk Welting、Vadim V. Bardin
DOI:10.1016/j.jfluchem.2008.11.004
日期:2009.3
The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C(6)F(5)HaIF(2) with BF3.NCCH3 in acetonitrile (donor solvent) led to [C(6)F(5)HaIF-(NCCH3)(n)][BF4]. The attempted generation of [C6F5BrF](+) from C6F5BrF2 and anhydrous HF or BF3 in weakly coordinating SO2CIF gave C6F5Br besides bromoperfluorocycloalkenes C6BrF7 and 1-BrC6F9. In reactions of C6F5IF2 with SbF5 in SO2CIF the primary observed intermediate (F-19 NMR, below 0 degrees C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C6F5I and 1-lC(6)F(9) at 20 degrees C. The reaction of C6F5IF4 with SbF5 in SO2CIF below -20 degrees C gave the cation [C6F5IF3](+) which decomposed at 20 degrees C to C6F5I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C6F13IF4 showed a different type of products in the fast reaction with AsF5 in CCl3F (-60 degrees C) which resulted in C6F14. Intermediate and final products of C(6)F(5)Hal(n-1) (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized. (C) 2008 Elsevier B.V. All rights reserved.