Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... A mild, convenient, halogen-exchange route to gem-difluorides and trifluorides. ... Reaction of -dihalides R 1 R 2 CX 2 (X= Cl or I) and of PhCCl 3 with AgBF 4 at room or sub-ambient temperatures affords the corresponding -difluorides and trifluoride in unoptimised yields of 35–84%.