THE SYNTHESIS OF ALPHA-TERT-BUTYL-OMEGA-[P-VINYLPHENYL]-TERMINATED POLY(2-METHYLPROPENE) MACROMONOMERS

In this communication a novel synthetic route to alpha-tert-butyl-omeg a-[p-vinylphenyl]-terminated poly(2-methylpropene) (PIB) macromonomers (P3 (VB); P5) is described: [GRAPHICS] Attempts to synthesize such ma cromonomers in both one- and two-step syntheses are described. The one -step method using 4-chloromethylstyrene/AlR3 as initiating system for the polymerization of 2-methylpropene did not yield linear macromonom ers but rather highly branched products. The alternative two-step synt hesis using 1-(2-bromoethyl)4-chloromethylbenzene (BCB) or BCB/AgSbF6 as initiator also failed to yield the desired products. Successful syn thetic routes, optimised on the basis of model experiments with low mo lar mass compounds, are also described for preparing the above macromo nomers. Both of these routes involve isopropenyl-terminated PIB, which is easily assessible by Inifer technique followed by dehydrohalogenat ion. Friedel-Crafts alkylation of phenol by the terminal olefin group of PIB, followed by subsequent esterification of the phenolic end-grou ps with 4-vinylbenzoyl chloride, affords the macromonomer P3(VB). Conv ersion of the terminal olefin group of PIB into a primary alcohol usin g 9-bora[3,3,1]-bicyclononane/H2O2, followed by esterification, yields the macromonomer P5.