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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 6
BKCSDE 19(6)
June 20, 1998 

Kinetics and Mechanism of the Aminolysis of Phenylacetyl Chlorides in Acetonitrile
Hai Whang Lee, Hi-Won Lee, Han Hoong Koh, Ikchoon Lee
The aminolysis reactions of phenylacetyl chlorides with anilines and N,N-dimethylanilines (DMAS) in acetonitrile at -15.0 ℃ are investigated. The magnitude of ρx (= -2.8 ∼ -2.9) and ρy (= 0.9 ∼ 1.3, after correcting for the fall-off), and the negative sign of ρxy (= -0.12) for the reactions with anilines suggest an associative SN2 mechanism. For the reactions with DMAs, the magnitude of these Hammett coefficients increases so that tighter bond making in the transition state (TS) is predicted. A nonlinear Hammett plots obtained for the DMAs with an electron acceptor substituent is interpreted to result from a more advanced degree of leaving group departure to assist closer approach of the bulky DMA in the TS. The normal secondary kinetic isotope effects (kH / kD > 1.0) involving deuterated anilines suggest partial deprotonation by hydrogen bonding to the departing chloride ion.
642 - 645
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