Preparation of first examples of R_FC≡CIF4 molecules. A study of the fluorination of selected 1-iodoalk-1-ynes with xenon difluoride/boron trifluoride

摘要

First examples of alk-1-yn-1-yliodine(V) molecules, CF3C≡CIF4 and C6F_(13)C≡CIF4, were prepared by fluorination of the corresponding 1-iodoperfluoroalk-1-ynes with XeF2 in 1,1,1,3,3-pentafluorobutane (PFB) in the presence of BF3. The reaction of l-iodo-2-(4-heptaf[uorotolyl)ethyne, 4-CF3C6F4C≡CI, with XeF2 (1.5 equiv) and BF3 resulted in a mixture of 4-CF3C6F4C≡CIF2 (main product), 4-CF3C6F4C≡CIF4, and trans-(4-CF3C6F4)CF≡CFI, whereas under the action of 3 equiv of XeF2/BF3 a complex mixture of polyfluoroorganics and IF5 resulted. Non-fluorinated C4H9C≡CI reacted with XeF2/BF3 preferentially under fluorine addition across the triple bond and gave mainly C4H9CF2CF2I. The differing reactivity of C_nF_(2n+2)C≡CI and C4H9C≡CI is in accordance with the experimentally proved different reactivity of the triple bond in C6F13C≡CH and C4H9O≡CH toward XeF2/BF3 in PFB. Compound C6F_(13)C≡CH was inert whereas C4H9C≡CH was converted into C4H9CF2CF2H (main product) under the same conditions.