vic-Difluoroalkanes are as inert as monofluoroalkanes toward NaOMe in MeOH. Stronger bases, however, can perform dehydrofluorinations relatively smoothly. KOCMe3 in THF at 75 Deg acts exclusively by an antiperiplanar process: meso- and dl-6,7-difluorododecane are converted to (E)- and (Z)-6-fluoro-6-dodecene, resp. Lithium diisopropylamide was an extremely powerful eliminating reagent when employed in hexane, while its reactivity is considerably diminished in di-Et ether and has almost completely vanished in THF. This solvent effect together with the loss of stereoselectivity points at an electrophilic assistance as the key event in lithium amide-induced dehydrofluorinations. [on SciFinder (R)]