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Published April 1994 | public
Journal Article Open

Competitive Chain Transfer by β-Hydrogen and β-Methyl Elimination for a Model Ziegler-Natta Olefin Polymerization System [Me_2Si(η^5-C_5Me_4)_2]Sc{CH_2CH(CH_3)_2}(PMe_3)


The reaction of OpSc(H) (PMe_3) (Op = {(η^5-C_5Me_4)_2SiMe_2}) with isobutene produces OpSc(CH_3)(PMe_3) along with isobutene, 2-methylpentane, isobutene, 2-methyl-l-pentene, propane, and n-pentane. These products arise from a series of reactions involving olefin insertion, β-CH_3 and (faster) β-H elimination which proceed until only the 2-methyl-1-alkenes (C_4H_8, C_6H_(12), etc.) and the predominant organoscandium product OpSc(CH_3)(PMe_3) remain. A transient observed in the reaction sequence has been unambiguously characterized as OpSc(CH_2CH_2CH_3) (PMe_3). Slower u bond metathesis involving the methyl C-H bonds of PMe_3 and the Sc-C bonds of the scandium alkyls accounts for the observation of saturated alkanes (2-methylalkanes (C_4H_(10), C_6H_(14), etc.), normal alkanes (C_3H_8, C_5H_(12), etc.), and a minor organoscandium product OpScCH_2-PMe_2 in the product mixture. b-Ethyl migration is not observed for the closely related 2-ethylbutyl derivative, OpSC{CH_2CH(C_2H_5)CH_2CH_3}(PMe_3), obtained from reaction of 2-ethyl-1-butene with OpSc(H)(PMe_3).

Additional Information

© 1994 American Chemical Society. Received July 27, 1993. We thank Dr. Les Field (University of Sydney) for his expert assistance in acquiring the NMR data. The work has been supported by USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER113431) and by Exxon Chemical Americas.

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Supplemental Material - om00016a018_si_001.pdf


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August 20, 2023
August 20, 2023