Polymerization allylbenzene

Butyl alcohol and benzene gave both mono- and di-i-butylbenzene (Simons et al., 37). Allyl alcohol reacted with benzene to produce both allylbenzene and 1,2-diphenylpropane. (Simons and Archer, 38.) The activity of the hydroxyl group is indicated in the fact that 2-phenyl-propanol was not separated. Benzyl alcohol reacted with benzene to form diphenylmethane (Simons and Archer, 39) despite the fact that this reaction is reported (Calcott et al., 34) to form 1,2,3,4,5,6-hexa-phenylcyclohexane by the polymerization of the alcohol. Isopropyl alcohol with benzene gave isopropylbenzene, 1,4-diisopropylbenzene,... 

Indeed it would be surprising if Staudinger s postulate of 1,3 polymerization would hold true in this case. To explain a backbone without pendant methyl groups one is forced to assume the following reaction sequence (a) propenylbenzene isomerizes to allylbenzene, CHg=CH-CH2-0, prior to propagation (b) the growing carbonium ion... 

We have substantiated the correctness of this last statement by polymerizing allylbenzene to a polymeric mixture, in which one component seems to be identical by infrared spectroscopy to that obtained by polymerizing propenylbenzene. Apparently, therefore, allylbenzene under electrophilic attack (partially) isomerizes to propenylbenzene prior to propagation, and the propenylbenzene then yields a conventional 1,2 enchainment, e. g.,... 

D Alelio et al. 150) came to similar conclusions from polymerizing allylbenzene with various Ziegler-Natta type and cationic catalysts. 

To corroborate that the epimerization reaction is responsible for the stereoerrors in the polypropylene chain, we treated 1-octene with complex 14 activated with MAO. The reaction resulted in the quantitative formation of frans-2-octene. In addition, the reaction of allylbenzene with the system 11/MAO at room temperature produced 100% conversion of the former to trans-methylstyrene. The isomerization results indicate that during the polymerization, the metal center in 14 is also able to migrate through the growing polymer chain, inducing branching and additional environments for the methyl ligands (Scheme 2) [124]. 

In addition to propylene, other nonconjugated olefins have been copolymerized with CO using enantiopure palladium catalysts. Allylbenzene, 1-butene, 1-heptene, 4-methyl-l-pentene, and cis-2-butene [84,85] as well as hydroxy- and carboxylic acid-functionalized monomers [87] have been polymerized to give optically active polymers. Waymouth, Takaya and Nozaki have recently reported the enantioselective cyclocopolymerization of 1,5-hexadiene and CO [88,89]. 

The literature [101, 102] cites the hydrogenation and isomerization of allylbenzene in the presence of palladium complexes on polymeric supports having oxygen-containing coordination groups like -OPh, -COOH, -OH. It was shown that the activity and selectivity of synthesized polymeric catalytic systems were affected by both the electron-donor properties of graft coordination groups and the solvent type. In the presence of the catalyst, the isomerization of allylbenzene to 1-propenylbenzene mainly yields the trans isomer. 

With a-methylstyrene (6, R = Ph), the yield of the diacetylation with acetic anhydride and perchloric or sulfoacetic acid affording 2,6-dimethyl-4-phenylpyrylium salts is lowered because of polymerization side products. Whereas the resulting phenyl group in position 4 (7) is deactivated towards electrophilic acylation, no such effect is exerted on a p-phenyl group, so that allylbenzene with acetic anhydride and perchloric acid affords a mixture of 2,6-dimethyl-3-phenvlpyrylium and 2,6-dimethyl-3-(para-acetyl-phenyl)-pyrylium perchlorates/ However, starting from a tertiary alcohol (17), 2,4,6-trimethyl-3-phenylpyrylium perchlorate (18) can be obtained without para-acetylation. ... 

To further clarify the participation of radical processes, Rondestvedt and Wark " " examined the reaction of allylbenzene with MA using various ratios of the reactants. In the presence of acetyl peroxide at 90-95°C no isolable 1 1 adduct was formed, the product being polymeric in nature (see Chapter 10). Furthermore, one usually obtains a polymeric by-product, particularly evident in a reaction run without an inhibitor. " The suggestion has been made that radical-initiated polymerization is a competing process. ... 

Reactions of SmCp 2 cmd Sm(Cp" )2(THF)2 with short chain alkenes and dienes In further studies comparing the reactivity of SmCp 2 and Sm(Cp )2(THF)2 with alkenes both complexes were subjected to reaction with ethene, propene, cis- and trans-l-hvXtnt, and allylbenzene (Evans et al., 1990d). Both reductants polymerize ethene to give polyethylene. 

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... 

The chemistry of polymerizations with monomer-isomerization-pre-ceeding-propagation is not confined to the catalysts of the Ziegler-Matta type, i.e., anionic coordinated mechanisms. For examjde, allylbenzene gives (among other products) poly-/3-methylst3 rene by a conventional cationic process, however, this s tem is not well defined because of disturbing side reactions (alkylations, etc.) also occur. 

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