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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 22, Number 4
BKCSDE 22(4)
April 20, 2001 

Nucleophilic Substitution Reactions of Thiophenyl Dimethylacetates and Trimethylacetates with Benzylamines in Acetonitrile
Hyuck Keun Oh, Chi Yeul Park, Jae Myon Lee, Ikchoon Lee
Aminolysis, Kinetics and mechanism, Acyl transfer reaction.
The kinetics and mechanism of the reactions of thiophenyl dimethylacetates (TDA) and trimethylacetates (TTA) with benzylamines in acetonitrile are studied. The reactions are first order in both the amine and the substrate. Relatively large values of βXnuc = 1.1-1.5; TDA and 1.1-1.5; TTA) and βZlg = -1.8~-2.0; DTA and -1.3~-1.6; TTA) for benzylamines, significantly large kH/kD values (=1.2-1.5; DTA and 1.2-1.5; TTA) involving deuterated benzylamines, and large ρXZ (=0.82; TDA and 1.05; TTA) values are interpreted to indicate stepwise acyl transfer mechanism, but with the hydrogen bonded four center type transition state for benzylamine. The relatively greater magnitudes of ρXZ and the secondary kinetic isotope effects involving deuterated nucleophiles are in line with the proposed mechanism.
383 - 387
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