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Concerted mechanism of the aminolysis of 2,4,6‐trinitrophenyl o‐ethyl dithiocarbonate in aqueous ethanol
Author(s) -
Castro Enrique A.,
Cubillos María,
Muñoz Gabriel,
Santos José G.
Publication year - 1994
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/kin.550260510
Subject(s) - chemistry , aminolysis , alicyclic compound , concerted reaction , aqueous solution , ionic strength , tetrahedral carbonyl addition compound , amine gas treating , ethanol , solvent , ionic liquid , medicinal chemistry , inorganic chemistry , organic chemistry , catalysis , nucleophile
The reactions of the title substrate with a series of secondary alicyclic amines are subjected to a kinetic study in 44 wt% aqueous ethanol, 25.0°C, and ionic strength 0.2 M (KCl). The Brönsted‐type plot (log k N vs. p K a of the amine, where k N is the second‐order rate coefficient) obtained is linear with slope β = 0.53, which indicates a concerted mechanism. The predicted Brönsted break for a hypothetical stepwise mechanism is p K a 0= 8.7, which was not observed (p K a range of amines: 6–11). The same reaction in water is stepwise, which shows that the tetrahedral intermediate found in water is much destabilized by the change of solvent from water to aqueous ethanol. © 1994 John Wiley & Sons, Inc.