Preparation of first examples of RFCCIF4 molecules. A study of the fluorination of selected 1-iodoalk-1-ynes with xenon difluoride/boron trifluoride

First examples of alk-1-yn-1-yliodine(V) molecules, CF3CCIF4 and C6F13CCIF4, 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 1-iodo-2-(4-heptafluorotolyl)ethyne, 4-CF3C6F4CCI, with XeF2 (1.5 equiv) and BF3 resulted in a mixture of 4-CF3C6F4CCIF2 (main product), 4-CF3C6F4CCIF4, and trans-(4-CF3C6F4)CFCFI, whereas under the action of 3 equiv of XeF2/BF3 a complex mixture of polyfluoroorganics and IF5 resulted. Non-fluorinated C4H9CCI reacted with XeF2/BF3 preferentially under fluorine addition across the triple bond and gave mainly C4H9CF2CF2I. The differing reactivity of CnF2n+1CCI and C4H9CCI is in accordance with the experimentally proved different reactivity of the triple bond in C6F13CCH and C4H9CCH toward XeF2/BF3 in PFB. Compound C6F13CCH was inert whereas C4H9CCH was converted into C4H9CF2CF2H (main product) under the same conditions.