3- Phenylpropene. polymerization

Cationic polymerization of 3-phenylpropene (CH2= CHCH2Ph) affords A as the major product rather than B. Draw a stepwise mechanism to account for this observation. 

There is eertainly strong experimental evidenee for the existenee of radieal-solvent eom-plexes. For instanee, Russelk and eo-workers eolleeted experimental evidenee for radi-eal-eomplex formation in studies of the photoehlorination of 2,3 -dimethylbutane in various solvents. In this work, different produets were obtained in aliphatie and aromatie solvents, and this was attributed to formation of a jr-eomplex between the Cl atom and the aromatie solvent. Complex formation was eonfirmed by flash photolysis. Complex formation was also proposed to explain experimental results for the addition of triehloromethane radieal to 3-phenylpropene and to 4-phenyl-1-butene and for hydrogen abstraetion of the t-butoxy radieal from 2,3-dimethylbutane. Furthermore, eomplexes between nitroxide radieals and a large number of aromatie solvents have been deteeted. Evidenee for eomplexes between polymer radieals and solvent moleeules was eolleeted by Flatada et al., in an analysis of initiator fragments from the polymerization of MMA-d with AIBN and BPO initiators. They diseovered that the ratio of disproportionation to eombination depended on the solvent, and interpreted this as evidenee for the formation of a polymer radieal-solvent eomplex that suppresses the disproportionation reaetion. 

In the coordinated anicHiic pol3unerization invoilving monomer-isomerization of butene-2 above 60° C only the homopolymer of butene-1 is obtained in spite of the presence of a large excess od butene-2 in the system. Similar results were obtained in the polymerizations of pentene-2 and hexene-2 at 80° C winch yielded by a monomer-isomerization mechanism polypentene-1 and polybexene-1, reflectively 17). It was also found that in the copolymerizations of butene-2 with propylene and 3-phenylpropene (allylbenzene) with AlEtj/TiCIa or AlEtj/VQ , catalyst with an added isomerization catalyst (seeTable 3) the homopolymers... 

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