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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 23, Number 2
BKCSDE 23(2)
February 20, 2002 

 
Title
Kinetics and Mechanism of the Addition of Benzylamines to Ethyl- α-cyanocinnamates in Acetonitrile
Author
Hyuck Keun Oh, Jin Hee Yang, Young Hee Hwang, Hai Whang Lee, Ikchoon Lee
Keywords
Nucleophilic addition reaction, .Natural. bond .orbital calculation, Cross-interaction constant, Kinetic isotope effect.
Abstract
Nucleophilic addition reactions of benzylamines (BA; XC6H4CH2NH2) to ethyl-α-cyanocinnamates (ECC;YC6H4CH=C(CN)COOEt) have been investigated in acetonitrile at 30.0℃. The rate is first order with respect to BA and ECC. The rate is slower than that expected from the additive effect of σ- or R- for the activating groups (CN and COOEt). Natural. bond . orbital π*c=c calculations show that the contribution of COOEt group may not be fully effective despite the coplanar molecular structure. The selectivity parameters including the cross-interaction constant ( ρXY = -0.22) indicate that the addition occurs in a single step. The kinetic isotope effects (kH/kD=.2.5-2.8) involving deuterated BA (XC6H4CH2ND2) nucleophiles and activation parameters (ΔH=4~6 kcal mol-1 ; ΔS=-45~ -52 e.u.) suggest a cyclic transition state in which N-Cα and H-Cβ bonds are formed concurrently.
Page
221 - 224
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