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Kinetics and mechanism of the aminolysis of O‐ethyl S‐aryl dithiocarbonates in acetonitrile
Author(s) -
Oh Hyuck Keun,
Lee Jun Yong,
Yun Jeong Hwan,
Park Young Sook,
Lee Ikchoon
Publication year - 1998
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1998)30:6<419::aid-kin4>3.0.co;2-v
Subject(s) - aminolysis , chemistry , acetonitrile , nucleophile , medicinal chemistry , deuterium , kinetic isotope effect , aryl , hydrogen bond , kinetics , reaction mechanism , stereochemistry , molecule , organic chemistry , catalysis , physics , alkyl , quantum mechanics
The aminolysis reactions of O‐ethyl S‐(Z‐phenyl) dithiocarbonates (Z= p ‐CH 3 , H, p ‐Cl, and p ‐NO 2 ) with anilines (AN) and N , N ‐dimethylanilines (DMA) in acetonitrile at 30.0°C are investigated. Relatively small values of β X (β nuc ,0.4 ca. 0.7) and β Z (β lg −0.1 ca. −0.4) for both ANs and DMAs, significantly large k H / k D values (1.1 ca. 1.9) involving deuterated anilines, and large negative ρ XZ values for ANs (−0.56) are interpreted to indicate a concerted mechanism for both ANs and DMAs but with a hydrogen bonded four‐center type transition state (TS) for ANs. The relative leaving ability, k (Z= p ‐NO 2 )/ k (Z= p ‐CH 3 ), is smaller for ANs than for DMAs, especially for a weaker nucleophile (1.9 and 4.7 for AN and DMA, respectively, with X= p ‐Cl). This suggests that the rate enhancement by the hydrogen‐bond formation in the four‐center type TS for AN is greater for a weaker nucleofuge (Z= p ‐CH 3 ), especially when the nucleophile (X= p ‐Cl) is weaker. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 419–423,1998