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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 14, Number 5
BKCSDE 14(5)
May 20, 1993 

Kinetics and Mechanism of the Aminolysis of Benzenesulfonyl, Benzoyl and Benzyl Halides
Byung Choon Lee, Dong Sook Sohn, Ji Hyun Yoon, Sun Mo Yang, Ikchoon Lee
Kinetic studies are conducted for the reactions of Y-benzoyl, Y-benzenesulfonyl and Y-benzyl halides with X-anilines in acetonitrile, and the transition state (TS) structures and their variations with substituents X and Y are discussed. The magnitude of the cross-interaction constants, ρxy, is the largest and the inverse secondary kinetic isotope effect (SKIE), kH/kD < 1.0, with deuterated aniline nucleophiles is the smallest for benzoyl fluoride reflecting the tightest TS for this compound. The SKIEs for sulfonyl halides are relatively large due to a relatively large, diffuse nature of the reaction center, S, causing weaker steric hindrance to the vibrations of the two N-H(D) bonds. For benzoyl and sulfonyl halides, the trends in kH/kD and │ rX│ variations with σY contradict each other, which is rationalized by the negative charge accumulation on the reaction center, CO and SO2, causing inefficient transfer for the substrate with an electron donating substituent.
621 - 625
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