Document Detail

Hydroboration kinetics: Unusual kinetics for the reaction of 9-borabicyclo[3.3.1]nonane with representative alkenes.
MedLine Citation:
PMID:  16592773     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The kinetics of hydroboration of alkenes with 9-borabicyclo[3.3.1]nonane dimer, (9-BBN)(2), exhibit interesting characteristics. With more reactive alkenes, such as 1-hexene, 2-methyl-1-pentene, 3,3-dimethyl-1-butene, and cyclopentene, the reaction exhibits first-order kinetics, first order in (9-BBN)(2) and zero order in alkene. On the other hand, with less reactive alkenes, such as cyclohexene, 1-methylcyclohexene, and 2,3-dimethyl-2-butene, the reaction exhibits three-halves-order kinetics, first order in alkene and one-half order in (9-BBN)(2). These kinetics can be accounted for in terms of the following mechanism:(9-BBN)(2) right arrow over left arrow 2 9-BBN9-BBN + alkene --> B-alkyl-9-BBNIn the case of the more reactive alkenes, the rate-determining step is the dissociation of the dimer. With less reactive alkenes, the reaction of the alkene with the monomer becomes the rate-determining step. For certain alkenes, such as 2-methyl-2-butene and cis-3-hexene, neither of the two steps is a decisive rate-determining step. Therefore, the reaction exhibits kinetic behavior between that of first- and three-halves-order kinetics.
H C Brown; K K Wang; C G Scouten
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  77     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1980 Feb 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-06-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  698-702     Citation Subset:  -    
Richard B. Wetherill Laboratory, Purdue University, West Lafayette, Indiana 47907.
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