A dehydrofluorinating agent which can serve as both the dehydrofluorinating agent and the organosilane coupling agent is of the formula: ##STR2## having reactive functionality, where R is at least one hydrogen atom and is selected from the group of hydrogen, alkyl, alkenyl, alkylaryl or aryl group with from 1 to 20 carbon atoms, R1 is an alkyl or alkenyl group with from 1 to 20 carbon atoms or an