Kinetic study of BH3 reduction of benzaldehydes: identification of effective reducing species

A kinetic study was carried out for the reaction of benzaldehyde and borane (BH3) in tetrahydrofuran. The effect of BH3 concentration on the rate constant showed that the reaction order with respect to BH3 was 1.6. Substituent effects gave a linear Hammett plot with a ρ value of −0.51. It was conclu...

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Bibliographic Details
Published in:Journal of physical organic chemistry 2012-06, Vol.25 (6), p.502-505
Main Authors: Abe, Masatsugu, Yamataka, Hiroshi
Format: Article
Language:English
Subjects:
catalytic transition state
metal hydride reduction
reaction order
substituent effect
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Summary:A kinetic study was carried out for the reaction of benzaldehyde and borane (BH3) in tetrahydrofuran. The effect of BH3 concentration on the rate constant showed that the reaction order with respect to BH3 was 1.6. Substituent effects gave a linear Hammett plot with a ρ value of −0.51. It was concluded that the reaction proceeds through a rate‐determining hydride‐transfer transition state with two BH3 molecules, in which one molecule of BH3 acts as a reducing agent and the other serves as a catalyst. Copyright © 2011 John Wiley & Sons, Ltd. Kinetic study for the reaction of benzaldehyde and BH3 in THF showed that the reaction order with respect to BH3 was 1.6. Substituent effects gave a linear Hammett plot with a ρ value of −0.51. It was concluded that the reaction proceeds through a rate‐determining hydride‐transfer TS, in which one molecule of BH3 act as reducing agent and the second BH3 molecules serves as catalyst.
ISSN:0894-3230
1099-1395
DOI:10.1002/poc.1945