| Автор | Camara, Susana |
| Автор | Gilbert, Bruce C. |
| Автор | Meier, Robert J. |
| Автор | van Duin, Martin |
| Автор | Whitwood, Adrian C. |
| Дата выпуска | 2003 |
| dc.description | EPR spectroscopy has been employed to study directly the selectivity of hydrogen-atom abstraction by some alkoxyl radicals from a variety of linear and branched alkanes, as well as linear alkenes, chosen as models for low molecular-weight polyolefin cross-linking systems. In situ thermal and photolytic approaches, as well as spin-trapping, have been employed to provide information relating to an accessible temperature range of 233â 453 K, in part to mimic conditions relevant to melt processing of polyolefins. Rate constants (in the range 3 Ã 10<sup>3</sup> â 3.7 Ã 10<sup>5</sup> dm<sup>3</sup> mol<sup>â 1</sup> s<sup>â 1</sup> per hydrogen) have been determined for Câ H abstraction at room temperature. Radical selectivity is largely governed by enthalpic effects (modelled via bond dissociation energy calculations and kinetic analysis). Direct evidence has been obtained for lack of reactivity, as a result of unfavourable steric interactions, for the secondary and tertiary Câ H bonds in 2,4-dimethylpentane and 2,4,6-trimethylheptane, models for polypropylene. This has been rationalized via free-energy calculations using DFT. |
| Формат | application.pdf |
| Издатель | Royal Society of Chemistry |
| Название | EPR and modelling studies of hydrogen-abstraction reactions relevant to polyolefin cross-linking and grafting chemistryElectronic supplementary information (ESI) available: computed 3D structures of the transition states of hydrogen abstraction from 2,4-dimethylpentane by tert-butoxyl radical. “1 ry24dmp.pdb”: H-abstraction from the methyl group (to generate a primary radical). “2ry24dmp.pdb”: H-abstraction from the central methylene group (to generate a secondary radical). “3 ry24dmp.pdb”: H-abstraction from the methine group (to generate a tertiary radical). See http://www.rsc.org/suppdata/ob/b2/b212543a/ |
| Тип | research-article |
| DOI | 10.1039/b212543a |
| Electronic ISSN | 1477-0539 |
| Print ISSN | 1477-0520 |
| Журнал | Organic & Biomolecular Chemistry |
| Том | 1 |
| Первая страница | 1181 |
| Последняя страница | 1190 |
| Аффилиация | Camara Susana; University of York, Department of Chemistry |
| Аффилиация | Gilbert Bruce C.; University of York, Department of Chemistry |
| Аффилиация | Meier Robert J.; DSM Research |
| Аффилиация | van Duin Martin; DSM Research |
| Аффилиация | Whitwood Adrian C.; University of York, Department of Chemistry |
| Выпуск | 7 |
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