Download 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. ... In the presence of various aluminum reagents, the difluoromethylene group (CF 2 ) in selected hydrofluorocarbons (HFCs) undergoes a Friedel–Crafts type reaction with aromatic compounds in satisfactory yields. ... In the presence of various aluminum reagents, the difluoromethylene group ...