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Kinetic resolution of racemic {alpha}-olefins with ansa-zirconocene polymerization catalysts: Enantiomorphic site vs. chain end control

Byers, Jeffery A. and Bercaw, John E. (2006) Kinetic resolution of racemic {alpha}-olefins with ansa-zirconocene polymerization catalysts: Enantiomorphic site vs. chain end control. Proceedings of the National Academy of Sciences of the United States of America, 103 (42). pp. 15303-15308. ISSN 0027-8424. PMCID PMC1622822. https://resolver.caltech.edu/CaltechAUTHORS:BYEpnas06

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PDF (Fig. 4. Melting temperature (Tm) vs. [rr] + [comonomer] (s) and <Liso> (l) in propylene and chiral monomer/propylene copolymers, respectively.)
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Abstract

Copolymerization of racemic {alpha}-olefins with ethylene and propylene was carried out in the presence of enantiopure C1-symmetric ansa metallocene, {1,2-(SiMe2)2({eta}5-C5H-3,5-(CHMe2)2)({eta}5-C5H3)}ZrCl2 to probe the effect of the polymer chain end on enantioselection for the R- or S-{alpha}-olefin during the kinetic resolution by polymerization catalysis. Copolymerizations with ethylene revealed that the polymer chain end is an important factor in the enantioselection of the reaction and that for homopolymerization, chain end control generally works cooperatively with enantiomorphic site control. Results from propylene copolymerizations suggested that chain end control arising from a methyl group at the beta carbon along the main chain can drastically affect selectivity, but its importance as a stereo-directing element depends on the identity of the olefin.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1073/pnas.0603071103DOIArticle
http://www.ncbi.nlm.nih.gov/pmc/articles/pmc1622822/PubMed CentralArticle
Additional Information:© 2006 by the National Academy of Sciences. Edited by Tobin J. Marks, Northwestern University, Evanston, IL, and approved July 21, 2006 (received for review April 18, 2006). Published online on October 10, 2006, 10.1073/pnas.0603071103. We thank Julia Kornfield and Lucia Fernandez-Ballester for DSC instrumentation and help with thermograph interpretation and Steven Cohen and Jerome Streeky at BP Chemicals (now Ineos) for molecular weight measurements. This work was supported by the National Science Foundation and the Department of Energy. Author contributions: J.A.B. and J.E.B. designed research; J.A.B. performed research; J.A.B. and J.E.B. analyzed data; and J.A.B. and J.E.B. wrote the paper. Conflict of interest statement: No conflicts declared. This article is a PNAS direct submission.
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Funding AgencyGrant Number
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Department of Energy (DOE)UNSPECIFIED
Subject Keywords:copolymerization; Ziegler–Natta
Issue or Number:42
PubMed Central ID:PMC1622822
Record Number:CaltechAUTHORS:BYEpnas06
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:BYEpnas06
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9958
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:28 Mar 2008
Last Modified:03 Jun 2020 19:34

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