Kinetics and mechanism of phenoxide anions addition to 4-nitrobenzofurazan in aqueous solution

2017 ◽  
Vol 95 (7) ◽  
pp. 723-728 ◽  
Author(s):  
S. Ben Salah ◽  
T. Boubaker ◽  
R. Goumont
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Rate Constants ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Hydroxide Ion ◽  
Order Rate

Second-order rate constants (k1) for the σ-complexation of 4-nitrobenzofurazan 1 with four 4-X-substituted phenoxide anions 2a–2d (X = OCH3, CH3, H and Cl) were measured in aqueous solution at 20 °C. Using this series of phenoxide anions as a reference, the electrophilicity parameter (E) of this electrophile 1 has been evaluated according to Mayr’s approach. With the E value of –9.42, Mayr’s equation was found to correctly predict the rate constants for the reactions of 1 with hydroxide ion in H2O and a 1:1 ratio of H2O to CH3CN. However, the large βnuc value of 1.12 obtained in the present work is clearly consistent with a single electron transfer (SET) mechanism.

Rates of Reaction of the Sulfoxides and Sulfones of Sulfur Mustard and 2-Chloroethyl Ethyl Sulfide With Hydroxide Ion in Water

1995 ◽  
Vol 48 (10) ◽  
pp. 1781 ◽  
Author(s):  
RI Tilley ◽  
DR Leslie
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Sulfur Mustard ◽  
Second Order ◽  
Hydroxide Ion ◽  
Order Rate

The reactions of the sulfoxides and sulfones of sulfur mustard and an analogue, 2-chloroethyl ethyl sulfide, with hydroxide ion in aqueous solution at 25° have been studied. In contrast with the behaviour of the parent sulfides, for which exclusive substitution of chlorine is observed under comparable conditions, the oxidized compounds react through base-catalysed elimination of HCl to give the corresponding alkenes. Second-order rate constants for these reactions are reported and implications for the metabolism of sulfur mustard are discussed.

Studies of Reactions between Flavins and Quinones, Mercaptans, and Enolates

1972 ◽  
Vol 27 (9) ◽  
pp. 1016-1020 ◽  
Author(s):  
Morton J. Gibian ◽  
D. Lauriston Elliott ◽  
Charles Kelly ◽  
Brad Borge ◽  
Kirklen Kupecz
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Redox Reaction ◽  
Radical Anion ◽  
Second Order ◽  
Ph Values ◽  
Order Rate

A. Equilibrium and second-order rate constants have been measured for the redox reaction between phthaloquinone and dihydroriboflavin (and its reverse) at a number of pH values. The equilibria and kinetic determinations are in agreement. No intermediates could be found in the reaction, and it is proposed that with this and other quinones electron transfer occurs within a complex of the flavin and hydroquinone (or dihydroflavin and quinone). B. A survey of the reaction between mercaptans and flavins is reported, as well as data showing that with mercaptoethanol the reaction is reversible, the disulfide and reduced flavin giving mercaptan and flavin. C. The reaction of alkylphenone enolates with isoalloxazine is described. This reaction leads t 50% isoalloxazine radical anion and an adduct of the enolate with the ketone. A possible route for this process is discussed.

Octahedral cobalt(III) complexes of the chloropentanimine type. XXX. The thallium(III)-induced aquation of some cis-Halogeno(amine)bis(ethylenediamine)cobalt(III) cations in aqueous solution

1973 ◽  
Vol 26 (6) ◽  
pp. 1235 ◽  
Author(s):  
SC Chan ◽  
SF Chan
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Activation Parameters ◽  
Second Order ◽  
Alternative Possibility ◽  
Order Rate ◽  
Leaving Group ◽  
Activated Complex

The second-order rate constants for the thallium(III)-induced aquation of cis-[Co(en)2(RNH2)Cl]2+ cations, where R is H, Me, Et, Prn, and Pri, have been measured in aqueous solution over a range of temperatures, and the activation parameters calculated. The kinetic results are discussed in terms of a rapid pre-equilibrium formation of an activated complex Co-Cl-Tl, followed by a simple rate-determining aquation in which TlCl2+ acts as the leaving group, although the alternative possibility of a rate-determining attack by Tl3+ cannot be excluded. In the case of R = H, the investigations have been extended to the corresponding bromo cation which reacts some 50 times faster than its chloro analogue.

Alkaline cleavage of trihaloacetophenones

1990 ◽  
Vol 68 (9) ◽  
pp. 1640-1642 ◽  
Author(s):  
J. Peter Guthrie ◽  
John Cossar
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Second Order ◽  
Order Rate ◽  
Alkaline Cleavage ◽  
Leaving Groups

Rate constants for haloform cleavage of trifluoro-, trichloro-, and tribromoacetophenone have been measured in aqueous solution; apparent second-order rate constants for reaction by the monoanion are in the ratio 1:5.3 × 1010:2.2 × 1013. Keywords: haloform cleavage, reactivity, trihalomethide leaving groups.

Nonylphenols degradation in the UV, UV/H2O2, O3 and UV/O3 processes – comparison of the methods and kinetic study

2015 ◽  
Vol 71 (3) ◽  
pp. 446-453 ◽  
Author(s):  
E. Felis ◽  
K. Miksch
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radicals ◽  
Rate Constants ◽  
Uv Light ◽  
Second Order ◽  
Quantum Yields ◽  
Environmental Significance ◽  
Order Rate ◽  
Technical Mixture

This paper describes the results of experiments on the decomposition of selected nonylphenols (NPs) in aqueous solutions using the UV, UV/H2O2, O3 and UV/O3 processes. The goal of the research was to determine the kinetic parameters of the above-mentioned processes, and to estimate their effectiveness. These substances were selected because of their ubiquitous occurrence in the aquatic environment, resistance to biodegradation and environmental significance. As a result of the experiments, the quantum yields of the 4-n-nonylphenol (4NP) and NP (technical mixture) photodegradation in aqueous solution were calculated to be 0.15 and 0.17, respectively. The values of the second-order rate constants of the investigated compounds with hydroxyl radical and NP with ozone were also determined. The estimated second-order rate constants of 4NP and NP with hydroxyl radicals were equal to 7.6 × 108–1.3 × 109 mol−1 L s−1. For NP, the determined rate constant with ozone was equal to 2.01 × 106 mol−1 L s−1. The performed experiments showed that NP was slightly more susceptible to degradation by the UV radiation and hydroxyl radicals than 4NP. The study demonstrated also that the polychromatic UV-light alone and also in combination with selected oxidizers (i.e. hydrogen peroxide, ozone) may be successfully used for the removal of selected NPs from the aqueous medium.

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