Kinetics and mechanism of the aminolysis of O‐ethyl S‐aryl dithiocarbonates in acetonitrile

Oh, Hyuck Keun; Lee, Jun Yong; Yun, Jeong Hwan; Park, Sung Chul; Lee, Ikchoon

doi:10.1002/(sici)1097-4601(1998)30:6<419::aid-kin4>3.3.co;2-x

Cited by 16 publications

(28 citation statements)

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“…The kinetics and mechanisms of the aminolysis of O ‐alkyl S ‐aryl dithiocarbonates1–5 are well documented; nevertheless, those of O ‐aryl S ‐aryl dithiocarbonates have been less studied 6, 7…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reactions of O‐aryl S‐(4‐nitrophenyl) dithiocarbonates with anilines in aqueous ethanol

Castro

Gazitúa

Santos

2009

J of Physical Organic Chem

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The reactions of O-(4-methylphenyl) S-(4-nitrophenyl) dithiocarbonate and O-(4-chlorophenyl) S-(4-nitrophenyl) dithiocarbonate with a series of anilines are subjected to a kinetic investigation in 44 wt% ethanol-water, at 25.0 -C and an ionic strength of 0.2 M. The reactions are followed spectrophotometrically at 420 nm (appearance of 4-nitrobenzenethiolate anion). Under excess amine, pseudo-first-order rate coefficients (k obs ) are found. For the reactions of both substrates with anilines, plots of k obs versus free amine concentration at constant pH are nonlinear upwards, according to a second-order polynomial equation. This kinetic behavior is in agreement with a stepwise mechanism consisting of two tetrahedral intermediates, one zwitterionic (T W ) and the other anionic (T S ), with a kinetically significant proton transfer from T W to an aniline to yield T S . The rate equation was derived from the proposed mechanism. By nonlinear least-squares fitting of the rate equation to the experimental data, values of the rate micro-coefficients involved in both steps were determined.

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Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reactions of O‐aryl S‐(4‐nitrophenyl) dithiocarbonates with anilines in aqueous ethanol

Castro

Gazitúa

Santos

2009

J of Physical Organic Chem

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“…The kinetics and mechanisms of the aminolysis of O ‐alkyl S ‐aryl dithiocarbonates are well documented 1–10. The reactions of O ‐ethyl S ‐(2,4,6‐trinitrophenyl) dithiocarbonate (ETNPDTC) with secondary alicyclic (SA) amines1, 5 and quinuclidines (QUI),7 and those of O ‐ethyl S ‐(2,4‐dinitrophenyl) dithiocarbonate (EDNPDTC) with QUI,7 in aqueous ethanol at 44 wt%, proceed by a concerted mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, Lee and co‐workers have examined the kinetics of the reactions of O ‐ethyl S ‐aryl dithiocarbonates with anilines9 and benzylamines10 in acetonitrile, and concluded that these reactions are concerted.…”

Section: Introductionmentioning

confidence: 99%

Reactions of O‐aryl S‐aryl dithiocarbonates with pyridines in aqueous ethanol: kinetics and mechanism

Castro

Gazitúa

Santos

2009

J of Physical Organic Chem

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The reactions of O-(4-methylphenyl) S-(4-nitrophenyl) dithiocarbonate (1), O-(4-chlorophenyl) S-(4-nitrophenyl) dithiocarbonate (2), and O-(4-chlorophenyl) S-phenyl) dithiocarbonate (3) with a series of pyridines were subjected to a kinetic investigation in 44 wt% ethanol-water, at 25.0 -C and an ionic strength of 0.2 M. The reactions were followed spectrophotometrically. Under amine excess, pseudo-first-order rate coefficients (k obs ) were determined. For the studied reactions, plots of k obs versus free pyridine concentration at constant pH were linear, with the slope (k N ) independent of pH. The Brønsted-type plots for (1) and (2) were biphasic, suggesting a stepwise mechanism with a change in the rate-determining step, from breakdown to the formation of a tetrahedral intermediate (T W ), as the basicity of the pyridines increases. For the reactions of (3), at the pK a range of the pyridines studied, only the breakdown to products of T W was observed.a Both the pK a and k N values were determined in 44 wt% ethanol-water, at 25.0 8C, and ionic strength 0.2 M (KCl).

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“…15 Thus, concerted mechanisms are found for the aminolyses of S-(2,4-dinitrophenyl) 14 and S-(2,4,6-trinitrophenyl) 3b O-ethyl thiocarbonates in contrast to the stepwise mechanisms for the corresponding dithiocarbonates. 16 Less polar solvents are also conductive to a concerted mechanism as observed for the aminolysis of carbonates from stepwise in water to concerted in acetonitrile. 17 For example, the aminolysis of 2,4,6-trinitrophenyl O-ethyl dithiocarbonates is stepwise 18 (biphasic Brönsted plot) in water, but is concerted (βX = 0.53) in a less polar solvent (44 wt % aqueous EtOH).…”

Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of the Aminolysis of Aryl N-Allyl Thiocarbamates in Acetonitrile

Oh¹

2010

Bulletin of the Korean Chemical Society

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Kinetics and mechanism of the aminolysis of O‐ethyl S‐aryl dithiocarbonates in acetonitrile

Cited by 16 publications

References 0 publications

Kinetics and mechanism of the reactions of O‐aryl S‐(4‐nitrophenyl) dithiocarbonates with anilines in aqueous ethanol

Kinetics and mechanism of the reactions of O‐aryl S‐(4‐nitrophenyl) dithiocarbonates with anilines in aqueous ethanol

Reactions of O‐aryl S‐aryl dithiocarbonates with pyridines in aqueous ethanol: kinetics and mechanism

Kinetics and Mechanism of the Aminolysis of Aryl N-Allyl Thiocarbamates in Acetonitrile

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