Polyisobutenes are prepared by cationic polymerization of isobutene or
isobutene-containing hydrocarbon streams in the liquid phase in the
presence of boron trifluoride as a catalyst, the catalytic activity of the
boron trifluoride being partially or completely eliminated at a desired
time by means of a solid deactivator, by a process in which the solid
deactivator has boron trifluoride-binding primary, secondary, tertiary
and/or quaternary nitrogen atoms and is insoluble in the reaction mixture.
