Patent ID: 7217773

Claim:
A process for preparing polyisobutene having a content of terminal vinylidene groups of at least 75 mol %, comprising: polymerizing isobutene or isobutenic hydrocarbon mixtures in the liquid phase in the presence of a boron trifluoride complex catalyst of the composition (BF 3 ) a .L 1 b .L 2 c .L 3 d wherein L 1 is water, a primary C 1 –C 5 -alkanol and/or a secondary C 3 –C 5 -alkanol, L 2 is at least one aldehyde and/or one ketone, L 3 is an ether having at least 5 carbon atoms, a secondary alkanol having at least 6 carbon atoms, a primary alkanol having at least 6 carbon atoms and/or a tertiary alkanol, and wherein the b:a ratio is in the range from 0.9 to 3.0, the c:a ratio is in the range from 0.01 to less than 0.5, the d:a ratio is in the range from 0 to 1.0.