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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 28, Number 6
BKCSDE 28(6)
June 20, 2007 

 
Title
Kinetics and Mechanism of the Aminolysis of Diphenyl Phosphinic Chloride with Anilines
Author
Md. Ehtesham Ul Hoque, Hai Whang Lee*
Keywords
Anilinolysis of diphenyl phosphinic chloride, Frontside nucleophilic attack, Deuterium kinetic isotope effect
Abstract
The aminolyses of diphenyl phosphinic chloride (1) with substituted anilines in acetonitrile at 55.0 oC are investigated kinetically. Large Hammett ρ X (ρnuc = ?4.78) and Bronsted β X (βnuc = 1.69) values suggest extensive bond formation in the transition state. The primary normal kinetic isotope effects (kH/kD = 1.42-1.82) involving deuterated aniline (XC6H4ND2) nucleophiles indicate that hydrogen bonding results in partial deprotonation of the aniline nucleophile in the rate-limiting step. The faster rate of diphenyl phosphinic chloride (1) than diphenyl chlorophosphate (2) is rationalized by the large proportion of a frontside attack in the reaction of 1. These results are consistent with a concerted mechanism involving a partial frontside nucleophilic attack through a hydrogen-bonded, four-center type transition state.
Page
936 - 0
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