RESEARCH ARTICLE

 

A mechanistic study of hydroboration of 1-octene with 1,3,2-dithiaborolane and 1,3,2-dithiaborinane: Part 1. Synthesis and kinetic studies

 

 

Siphamandla W. Hadebe; Ross S. Robinson

Warren Research Laboratory, School of Chemistry, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa

 

 

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ABSTRACT

Alkylthioboranes 1,3,2-dithiaborolane and 1,3,2-dithiaborinane have been synthesized from the reaction of BH₃-SMe₂ with 1,2-ethanedithiol and 1,3-propanedithiol, respectively. These heterocyclic boranes disproportionated significantly during their synthesis. The rate constants, and the enthalpies and entropies of the hydroboration reaction of 1-octene with 1,3,2-dithiaborolane and 1,3,2-dithiaborinane have been investigated, and we have shown that hydroboration with these boranes is slow and proceeds via an associative mechanism.

Key words: Hydroboration, disproportionation, boranes, transition states

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Full text available only in PDF format.

 

Acknowledgements

Financial support from SASOL and the University of KwaZulu-Natal is gratefully acknowledged, as are Drs Arno de Klerk and Hein Strauss for collaborative involvement in this ongoing project. We also thank Mr Craig Grimmer for his assistance with the ¹¹B NMR studies, and the boron group at the University of KwaZulu-Natal for their support.

 

References and Notes

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13 The percentage integrals of the reactant and product were converted into concentrations and plotted against time in order to obtain the observed rate constants and the second order rate constants.

14 The reaction temperature was varied from 20 to 35 °C. It was unfavourable to go beyond 35 °C due to the low boiling solvent CH₂Cl₂. For each temperature a plot of concentration vs. time was plotted.

15 ΔΗ* = - (slope) x R and ΔS* = (y-intercept - 23.8) x R, where R is the gas constant.

16 J.R. Govender, Mechanistic and Kinetic Study of the Hydroboration of 1-and 4-Octene by Dialkylborane Dimers. M.Sc. thesis, University of Natal, Pietermaritzburg, South Africa, 2003.         [ Links ]

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Received 2 December 2008
Revised 8 February 2009
Accepted 9 February 2009

 

 

* Present address: Fischer-Tropsch Refinery Catalysis, Sasol Technology Research and Development, P.O. Box 1, Sasolburg 1947, South Africa.
** To whom correspondence should be addressed. E-mail: robinsonr@ukzn.ac.za