Hydrolysis kinetics and mechanism of diaryldithiocarbamates in 20% aqueous dioxane

1981 ◽  
Vol 46 (8) ◽  
pp. 1970-1975 ◽  
Author(s):  
Jaromír Mindl ◽  
Jiří Sulzer ◽  
Miroslav Večeřa
Keyword(s):  
Kinetic Study ◽  
Kinetics And Mechanism ◽  
Aqueous Dioxane ◽  
Hydrolysis Kinetics ◽  
Acid Media ◽  
Ph Range ◽  
Reaction Constants

Nine diaryldithiocarbamates have been prepared. Kinetic study of their hydrolysis has revealed that this hydrolysis proceeds by E1cB mechanism in the pH range 2 to 12. Values of activation entropies, reaction constants, Broensted coefficient, and comparison with reactivity of the corresponding N-methyl analogue have been used as criteria for the suggested mechanism. In acid media pH 2 to 0.4 and H0 -0.6 the hydrolysis follows a mechanism analogous to AAc2. Results of hydrolyses of dithiocarbamates, thiocarbamates and carbamates are compared.

Hydrolysis kinetics and mechanism of diarylthiocarbamates in 20% aqueous dioxane medium

1980 ◽  
Vol 45 (11) ◽  
pp. 3130-3139 ◽  
Author(s):  
Jaromír Mindl ◽  
Pavel Balcárek ◽  
Lubomír Šilar ◽  
Miroslav Večeřa
Keyword(s):  
Kinetic Studies ◽  
Kinetics And Mechanism ◽  
Activation Entropy ◽  
Aqueous Dioxane ◽  
Hydrolysis Kinetics ◽  
Reaction Constants ◽  
Hydrolysis Of

Substituted S-aryl and O-aryl N-arylthiocarbamates have been synthetized. Kinetic studies of hydrolysis of these compounds in 20% aqueous dioxane prove the E1cB mechanism. The found Hammett reaction constants, activation entropy values, Broensted coefficients, and comparison of reactivity with N-methyl analogues have been discussed as criteria of the mentioned mechanism. Hydrolysis results of thiocarbamates in the same medium are compared.

The kinetics and mechanism of the oxidation of mercaptoethanol by riboflavin

1977 ◽  
Vol 30 (6) ◽  
pp. 1387 ◽  
Author(s):  
JW Holden ◽  
L Main
Keyword(s):  
Kinetic Study ◽  
Acid Catalysis ◽  
Kinetics And Mechanism ◽  
Alternative Mechanism ◽  
Semiquinone Radical ◽  
Radical Intermediate ◽  
General Acid ◽  
Elimination Mechanism ◽  
Ph Range ◽  
Kinetic Form

Kinetic study of the oxidation of mercaptoethanol (RSH) by riboflavin (FlH) over the pH range 8.5-10.5 establishes that the rate is given by the term 0.036[FlH][RSH][RS-]]2 mol-2 s-1, there being no buffer catalysis. Any reactivity of the N 3-ionized riboflavin species (Fl-) is sufficiently low to be kinetically undetected. The kinetic form and lack of general acid catalysis are consistent with a nucleophilic (thiolate) 4a-addition-elimination mechanism previously proposed, but a possible alternative mechanism involving a flavin semiquinone (radical) intermediate is suggested.

Hydrolysis kinetics and mechanism of N'-(3-N-methylcarbamoyloxyphenyl)-N,N-dimethylformamidine

1980 ◽  
Vol 45 (4) ◽  
pp. 1065-1071 ◽  
Author(s):  
Alexandr Čegan ◽  
Jaroslav Šlosar ◽  
Miroslav Večeřa
Keyword(s):  
Reaction Mechanism ◽  
Paper Chromatography ◽  
Kinetics And Mechanism ◽  
Hydrolysis Rate ◽  
Hydrolysis Kinetics ◽  
Hydrolysis Products ◽  
Hydrolysis Rates ◽  
Ph Range ◽  
Hydrolysis Of

Hydrolysis of N' -(3-N-methylcarbamoyloxyphenyl)-N,N-dimethylformamidine (I) has been studied in mixture water-dioxane (4 : 1) at pH 1 to 13. The hydrolysis rates of methylcarbamoyl and dimethylformamidine groups are comparable within pH range 4 to 10, and they differ by as much as several orders of magnitude in pH ranges 1-3 and 11-13. The hydrolysis products of the whole pH range have been determined by paper chromatography, and reaction mechanism has been suggested on the basis of the measured hydrolysis rate constants.Effects of protonation and hydratation of dimethylformamidine group on the hydrolysis rate of the methylcarbamoyl group is discussed.

The Kinetics and Mechanism of Interaction of Fe40Ni40B20Amorphous Metallic Alloys with Mineral Acid Media

1999 ◽  
Vol 72 (8) ◽  
pp. 1927-1933
Author(s):  
Adam Košturiak ◽  
Ladislav Valko ◽  
Jirí Polavka ◽  
Milan Brutovsky ◽  
Harry Morris
Keyword(s):  
Mineral Acid ◽  
Metallic Alloys ◽  
Kinetics And Mechanism ◽  
Acid Media ◽  
Mechanism Of Interaction

Kinetics and mechanism of the formation of methacrylamide from 2-methyl-2-sulphatopropionamide in strong acid media

1991 ◽  
pp. 417 ◽  
Author(s):  
C. Dennis Hall ◽  
Christopher J. Leeding ◽  
Stephen Jones ◽  
Stephen Case-Green ◽  
Ian Sanderson ◽  
...  
Keyword(s):  
Strong Acid ◽  
Kinetics And Mechanism ◽  
Acid Media
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