An NMR study of alkyl exchange reactions between boron and aluminum: effect of such exchange reactions on the polymerizability of alkenyldialkylboranes by the Ziegler-Natta process

S. Ramakrishnan, Tze-chiang Chung

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Abstract

Alkyl exchange reactions between boron and aluminum were studied using 1H-NMR, to gain a better understanding of the behavior of various ω-alkenyldialkylboranes towards Ziegler-Natta catalysts. The reaction of a model borane, octyldimethylborane, with Et3Al, Et2AlCl and EtAlCl2 was investigated. The transfer of the methyl group from boron to aluminum was monitored as a function of time. The rate of transfer was found to be rapid in the case of Et3Al and decreased in the order: Et3Al » Et2AlCl > EtAlCl2. The extent of this transfer at equilibrium, followed the same order and a maximum of 92 mol percent of the methyl group was transferred in the case of Et3Al. Sterically hindered aluminum alkyls such as tri(isobutyl)aluminum was also found to undergo rapid exchange with octyldimethylborane. Sterically crowded boranes such as 1-hexenyl-9-BBN, however, did not undergo any exchange reaction with Et2AlCl.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalJournal of Organometallic Chemistry
Volume388
Issue number1-2
DOIs
StatePublished - May 15 1990

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Boron
Aluminum
boron
Nuclear magnetic resonance
Boranes
aluminum
nuclear magnetic resonance
boranes
Ziegler catalyst
Catalysts
dichloroethylaluminum

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

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title = "An NMR study of alkyl exchange reactions between boron and aluminum: effect of such exchange reactions on the polymerizability of alkenyldialkylboranes by the Ziegler-Natta process",
abstract = "Alkyl exchange reactions between boron and aluminum were studied using 1H-NMR, to gain a better understanding of the behavior of various ω-alkenyldialkylboranes towards Ziegler-Natta catalysts. The reaction of a model borane, octyldimethylborane, with Et3Al, Et2AlCl and EtAlCl2 was investigated. The transfer of the methyl group from boron to aluminum was monitored as a function of time. The rate of transfer was found to be rapid in the case of Et3Al and decreased in the order: Et3Al » Et2AlCl > EtAlCl2. The extent of this transfer at equilibrium, followed the same order and a maximum of 92 mol percent of the methyl group was transferred in the case of Et3Al. Sterically hindered aluminum alkyls such as tri(isobutyl)aluminum was also found to undergo rapid exchange with octyldimethylborane. Sterically crowded boranes such as 1-hexenyl-9-BBN, however, did not undergo any exchange reaction with Et2AlCl.",
author = "S. Ramakrishnan and Tze-chiang Chung",
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T2 - effect of such exchange reactions on the polymerizability of alkenyldialkylboranes by the Ziegler-Natta process

AU - Ramakrishnan, S.

AU - Chung, Tze-chiang

PY - 1990/5/15

Y1 - 1990/5/15

N2 - Alkyl exchange reactions between boron and aluminum were studied using 1H-NMR, to gain a better understanding of the behavior of various ω-alkenyldialkylboranes towards Ziegler-Natta catalysts. The reaction of a model borane, octyldimethylborane, with Et3Al, Et2AlCl and EtAlCl2 was investigated. The transfer of the methyl group from boron to aluminum was monitored as a function of time. The rate of transfer was found to be rapid in the case of Et3Al and decreased in the order: Et3Al » Et2AlCl > EtAlCl2. The extent of this transfer at equilibrium, followed the same order and a maximum of 92 mol percent of the methyl group was transferred in the case of Et3Al. Sterically hindered aluminum alkyls such as tri(isobutyl)aluminum was also found to undergo rapid exchange with octyldimethylborane. Sterically crowded boranes such as 1-hexenyl-9-BBN, however, did not undergo any exchange reaction with Et2AlCl.

AB - Alkyl exchange reactions between boron and aluminum were studied using 1H-NMR, to gain a better understanding of the behavior of various ω-alkenyldialkylboranes towards Ziegler-Natta catalysts. The reaction of a model borane, octyldimethylborane, with Et3Al, Et2AlCl and EtAlCl2 was investigated. The transfer of the methyl group from boron to aluminum was monitored as a function of time. The rate of transfer was found to be rapid in the case of Et3Al and decreased in the order: Et3Al » Et2AlCl > EtAlCl2. The extent of this transfer at equilibrium, followed the same order and a maximum of 92 mol percent of the methyl group was transferred in the case of Et3Al. Sterically hindered aluminum alkyls such as tri(isobutyl)aluminum was also found to undergo rapid exchange with octyldimethylborane. Sterically crowded boranes such as 1-hexenyl-9-BBN, however, did not undergo any exchange reaction with Et2AlCl.

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