Octahedral cobalt(III) complexes of the chloropentammine type. XXIII. The mercury(II)-induced aquation of some cis-Chloropyridinebis(ethylenediamine) cobalt(III) complexes

1971 ◽  
Vol 24 (10) ◽  
pp. 2071 ◽  
Author(s):  
SC Chan ◽  
SF Chan
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Second Order ◽  
Order Rate ◽  
Leaving Group ◽  
Inductive Effects ◽  
Activated Complex

The second-order rate constants for the mercury(II)-induced aquation of some cis-chloropyridinebis(ethylenediamine)cobalt(III) cations have been measured in aqueous solution over a range of temperatures. The results are interpreted in terms of the formation of an activated complex Co-Cl-Hg, which yields the aquo product by a unimolecular aquation with HgCl+ as the leaving group. The competitive influences of the steric and inductive effects of alkyl substituents are 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.

The mercury(II)-induced aquation of trans-Chloroamminebis(dimethylglyoximato)cobalt(III) complex

1975 ◽  
Vol 28 (5) ◽  
pp. 1133 ◽  
Author(s):  
S Chan ◽  
S Tan
Keyword(s):  
Rate Constants ◽  
Aqueous Ethanol ◽  
Association Constants ◽  
First Order ◽  
Order Rate ◽  
Leaving Group ◽  
Pseudo First Order ◽  
Activated Complex

The pseudo first-order rate constants for the mercury(II)-induced aquation of trans-[Co(Hdmg)2(NH3)Cl] (Hdmg = dimethylglyoximate ion) have been measured in aqueous and aqueous ethanol solutions (ethanol- water mole ratio 1 : 5.1) containing various excess amounts of mercury(II)ion at 273.2 K. Association constants of the complex formed with mercury(II) ion and rate constants for dissociation of the activated complex in both solutions have been calculated. The kinetic results are discussed in terms of formation of an activated complex Co-C1-Hg, followed by a simple rate-determining aquation in which HgCl+ acts as the leaving group.

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.

Hydrates of Quaternary Ammonium Aldehydes as Potential Reactivators of Sarin-Inhibited Acetylcholinesterase

1998 ◽  
Vol 63 (7) ◽  
pp. 1021-1030 ◽  
Author(s):  
Jiří Cabal ◽  
František Hampl ◽  
František Liška ◽  
Jiří Patočka ◽  
František Riedl ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Quaternary Ammonium ◽  
Second Order ◽  
Trimethylammonium Chloride ◽  
Natural Substrate ◽  
Order Rate ◽  
Diphenyl Phosphate ◽  
Bonding Site

Synthesis of 2- (5a), 3- (5b) and 4-formyl-1-methylpyridinium iodides (5c) and (2,2-dihydroxyethyl)trimethylammonium chloride (6a) is described. In aqueous solution aldehydes 5 exist predominantly as hydrates - geminal diols 7. The ability of the geminal diols 6a and 7 to reactivate acetylcholinesterase inhibited by isopropyl methylfluorophosphonate (Sarin) was tested in vitro. Although compounds 6a and 7 exhibit an affinity towards the acetylcholinesterase bonding site comparable with that of the natural substrate acetylcholine, their reactivation ability was negligible. Second-order rate constants for cleavage of 4-nitrophenyl diphenyl phosphate (PNPDPP) with anions of the studied geminal diols were measured in order to determine their nucleophilicity.

The Lewis-acidity of square-planar nickel(II) complexes. III. A kinetic study of the effects of substituents on the addition of 1,10-Phenanthroline to Bis(monothioacetylacetonato)nickel(II) and Bis(dithiophosphato)nickel(II) complexes in toluene

1978 ◽  
Vol 31 (7) ◽  
pp. 1439 ◽  
Author(s):  
MU Fayyaz ◽  
MW Grant
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Activation Parameters ◽  
Adduct Formation ◽  
Second Order ◽  
Lewis Acidity ◽  
Order Rate ◽  
Measured Rate ◽  
Square Planar ◽  
Inductive Effects

The second-order rate constants and activation parameters for the addition of 1,10-phenanthroline to bis(dialkyldithiophosphato)nickel(II) complexes and substituted bis(monothioacetylacetonato)-nickel(II) complexes in toluene have been measured. Rate constants are in the range 102-108 1. mol-1 s-1 at 25°C, while ΔH‡ is in the range 10-50 kJ mol-1 and ΔS‡ is in the range from -30 to -110 J mol-1 K-1. The higher rate constants, smaller ΔH‡ and more negative ΔS‡ values are associated with complexes with electron- withdrawing substituents. The results are related to the thermo- dynamics of adduct formation, the inductive effects of the substituents and the pKa of the ligands.

Styrene Forming Elimination Reaction from β-Phenylethylphosphonium Salts+

1983 ◽  
Vol 38 (1) ◽  
pp. 115-116 ◽  
Author(s):  
S. Alunni ◽  
G. Giulietti
Keyword(s):  
Rate Constants ◽  
Second Order ◽  
Elimination Reaction ◽  
Order Rate ◽  
Leaving Group

β-Phenylethylphosphonium salts in RO-/ROH give styrene in amount depending on the steric requirements of the nucleophile and of the salt. The % of styrene formed increases from 22.9 with leaving group PPH3 to 85.0 with leaving group P(<-BU)3 in t-BuOK/t-BuOH. Second order rate constants at 30 °C in t-BuOK/t-BuOH are 1.1 · 10-2lm-1s-1 with leaving group P(n-Bu)3 and 0.96- 10-2 lm-1s-1 with leaving group P (cyclohexyl)3. The data are consistent with a mechanism of β-elimination.

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.

Inhibition in Purified Systems and in Human Plasma of Chimaeric Plasminogen Activators Consisting of the NH2-Terminal Region of Tissue-Type Plasminogen Activator and the COOH-Terminal Region of UrokinaseType Plasminogen Activator

1988 ◽  
Vol 60 (02) ◽  
pp. 247-250 ◽  
Author(s):  
H R Lijnen ◽  
L Nelles ◽  
B Van Hoef ◽  
F De Cock ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Rate Constants ◽  
Plasminogen Activators ◽  
Second Order ◽  
Tissue Type ◽  
Single Chain ◽  
Chain Molecules ◽  
Order Rate ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

SummaryRecombinant chimaeric molecules between tissue-type plasminogen activator (t-PA) and single chain urokinase-type plasminogen activator (scu-PA) or two chain urokinase-type plasminogen activator (tcu-PA) have intact enzymatic properties of scu-PA or tcu-PA towards natural and synthetic substrates (Nelles et al., J Biol Chem 1987; 262: 10855-10862). In the present study, we have compared the reactivity with inhibitors of both the single chain and two chain variants of recombinant u-PA and two recombinant chimaeric molecules between t-PA and scu-PA (t-PA/u-PA-s: amino acids 1-263 of t-PA and 144-411 of u-PA; t-PA/u-PA-e: amino acids 1-274 of t-PA and 138-411 of u-PA). Incubation with human plasma in the absence of a fibrin clot for 3 h at 37° C at equipotent concentrations (50% clot lysis in 2 h), resulted in significant fibrinogen breakdown (to about 40% of the normal value) for all two chain molecules, but not for their single chain counterparts. Preincubation of the plasminogen activators with plasma for 3 h at 37° C, resulted in complete inhibition of the fibrinolytic potency of the two chain molecules but did not alter the potency of the single chain molecules. Inhibition of the two chain molecules occurred with a t½ of approximately 45 min. The two chain variants were inhibited by the synthetic urokinase inhibitor Glu-Gly-Arg-CH2CCl with apparent second-order rate constants of 8,000-10,000 M−1s−1, by purified α2-antiplasmin with second-order rate constants of about 300 M−1s−1, and by plasminogen activator inhibitor-1 (PAI-1) with second-order rate constants of approximately 2 × 107 M−1s−1.It is concluded that the reactivity of single chain and two chain forms of t-PA/u-PA chimaers with inhibitors is very similar to that of the single and two chain forms of intact u-PA.

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