Mechanism of the alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio- and dithiocarbonates
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Date
1999
Journal Title
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Publisher
ROYAL SOC CHEMISTRY
Abstract
The alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio- and dithiocarbonates, 1 and 2, respectively, were studied kinetically in 5% dioxane in water, at 25.0 degrees C, and ionic strength 0.2 mol dm(-3) (KCl). Two kinetic processes, well separated in time, were detected. The fast process involves the formation of a sigma-complex by addition of HO- to one of the unsubstituted positions of the aromatic ring, followed by fast ionisation of this complex. The slow process leads to the formation of a mixture of 2,4,6-trinitrophenoxide and 2,4,6-trinitrobenzenethiolate ions in a 10 : 1 ratio, respectively, in the reaction of 2, and to a mixture in a 2. 1 ratio in the reaction of 1, independent of KOH concentration. Although the substrates show different kinetic behaviour with KOH concentration, the results can be discussed on the basis of a common reaction mechanism.
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Keywords
NUCLEOPHILIC AROMATIC-SUBSTITUTION, SINGLE-ELECTRON TRANSFER, SIGMA-ADDUCT FORMATION, CONCERTED MECHANISM, LEAVING GROUPS, KINETICS, AMINOLYSIS, AMINES, THIOCARBONATE, 2,4-DINITROPHENYL