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South African Journal of Chemistry
On-line version ISSN 1996-840X
Print version ISSN 0379-4350
S.Afr.j.chem. (Online) vol.62 Durban 2009
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
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
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
1. H.C. Brown, Organic Synthesis via Boranes, John Wiley & Sons, New York, NY, USA, 1975. [ Links ]
2 (a) G. Wilkinson, Comprehensive Organometallic Chemistry, Pergamon Press, Oxford, UK, 1982, p. 161; (b) R.S. Dhillon, Hydroboration and Organic Synthesis, Springer-Verlag, Berlin and Heidelberg, Germany, 2007. [ Links ]
3 B.M. Mikhailov, T.A. Shchegoleva and E.M. Shashakova, Izv. Akad. Nauk SSSR, Otd. Khim., English translation, 1963, 12, 443-445. [ Links ]
4 B.M. Mikhailov, T.A. Shchegoleva, E.M. Shashakova and V.D. Sheludyakova, Izv. Akad. Nauk SSSR, Otd. Khim., English translation, 1962, 11, 1143-1146. [ Links ]
5 D.J. Pasto, C.C. Cumbo and P. Balasubramaniyan, J. Am. Chem. Soc., 1966, 88, 2187-2194. [ Links ]
6 B.Z. Egan, S.G. Shore and J.E. Bonnell, Inorg. Chem., 1964, 3, 1024-1027. [ Links ]
7 A.B. Burg and R.I. Wagner, J. Am. Chem. Soc., 1954, 76, 3307-3310. [ Links ]
8 S. Thaisrivongs and J.D. Wuest, J. Org. Chem, 1977, 42, 3243-3247. [ Links ]
9 B.M. Mikhailov and T.A. Shchegoleva, Dokl. Akad. Nauk SSSR, 1960, 131, 843-846. [ Links ]
10 T.A. Shchegoleva, E.M. Shashakova, V.D. Sheludyakova and B.M. Mikhailov, Izv. Akad. Nauk SSSR, Otd. Khim., 1960,131, 1307-1309. [ Links ]
11 S. Kim, S.S. Kim, S.T. Lim and S.C. Shim, J. Org. Chem., 1987, 52, 2114-2116. [ Links ]
12 Microcal™ Origin™ Ver. 5.0, Microcal Software, Inc., Northampton, MA, USA, 1997. [ Links ]
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 ]
17 S.W. Hadebe, R.S. Robinson and H.G. Kruger, S. Afr. J. Chem, 2009, 62, 84-87. [ Links ]
18 D.D. Perrin, W.F.L. Armarego and D.R. Perrin, Purification of Laboratory Chemicals, 2nd edn., Pergamon Press, Oxford, UK, 1980, p. 218. [ Links ]
19 K. Niedenzu, I.A. Boenig and E.F. Rothegery, Chem. Ber., 1972, 105, 2258-2268. [ Links ]
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