The Hydrolysis of AuCl 4 − and the Stability of Aquachlorohydroxocomplexes of Gold(III) in Aqueous Solution

2009 ◽  
Vol 38 (6) ◽  
pp. 725-737 ◽  
Author(s):  
I. V. Mironov ◽  
E. V. Makotchenko
Keyword(s):  
Aqueous Solution ◽  
The Stability ◽  
Hydrolysis Of

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

Modelling the Hydrolysis of Iron-Sulfur Clusters

2019 ◽  
Author(s):  
Murilo H. Teixeira ◽  
Felipe Curtolo ◽  
Sofia R. G. Camilo ◽  
Martin J. Field ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Density Functional ◽  
Catalytic Efficiency ◽  
Implicit Solvent ◽  
Hybrid Functional ◽  
Iron Sulfur ◽  
The Stability ◽  
Dynamics Simulations ◽  
High Level ◽  
Hydrolysis Of

<div>Iron-sulfur (FeS) clusters are essential metal cofactors involved in a wide variety of biological functions. Their catalytic efficiency, biosynthesis and regulation depend on FeS stability in aqueous solution. Here, molecular modelling is used to investigate the hydrolysis of an oxidized (ferric) mononuclear FeS cluster by bare dissociation and water substitution mechanisms in neutral and acidic solution. First, approximate electronic structure descriptions of FeS reactions by density functional theory are validated against high-level wave-function CCSD(T) calculations. Solvation contributions are evaluated by an all-atom model with hybrid quantum chemical/molecular mechanical (QM/MM) potentials and enhanced sampling molecular dynamics simulations. The free energy profile obtained for FeS cluster hydrolysis indicates the hybrid functional M06 together with an implicit solvent correction capture the most important aspects of FeS cluster reactivity in aqueous solution. Then, 20 reaction channels leading to two consecutive Fe--S bond ruptures were explored with this calibrated model. For all protonation states, nucleophilic substitution with concerted bond breaking and forming to iron is the preferred mechanism, both kinetic and thermodynamically. In neutral solution, proton transfer from water to the sulfur leaving group is also concerted. Dissociative reactions show higher barriers and will not be relevant for FeS reactivity when exposed to solvent. These hydrolysis mechanisms may help to explain the stability and catalytic mechanisms of FeS clusters of multiple sizes and proteins</div><div><br></div>

Modelling the Hydrolysis of Iron-Sulfur Clusters

2019 ◽  
Author(s):  
Murilo H. Teixeira ◽  
Felipe Curtolo ◽  
Sofia R. G. Camilo ◽  
Martin J. Field ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Density Functional ◽  
Catalytic Efficiency ◽  
Implicit Solvent ◽  
Hybrid Functional ◽  
Iron Sulfur ◽  
The Stability ◽  
Dynamics Simulations ◽  
High Level ◽  
Hydrolysis Of

<div>Iron-sulfur (FeS) clusters are essential metal cofactors involved in a wide variety of biological functions. Their catalytic efficiency, biosynthesis and regulation depend on FeS stability in aqueous solution. Here, molecular modelling is used to investigate the hydrolysis of an oxidized (ferric) mononuclear FeS cluster by bare dissociation and water substitution mechanisms in neutral and acidic solution. First, approximate electronic structure descriptions of FeS reactions by density functional theory are validated against high-level wave-function CCSD(T) calculations. Solvation contributions are evaluated by an all-atom model with hybrid quantum chemical/molecular mechanical (QM/MM) potentials and enhanced sampling molecular dynamics simulations. The free energy profile obtained for FeS cluster hydrolysis indicates the hybrid functional M06 together with an implicit solvent correction capture the most important aspects of FeS cluster reactivity in aqueous solution. Then, 20 reaction channels leading to two consecutive Fe--S bond ruptures were explored with this calibrated model. For all protonation states, nucleophilic substitution with concerted bond breaking and forming to iron is the preferred mechanism, both kinetic and thermodynamically. In neutral solution, proton transfer from water to the sulfur leaving group is also concerted. Dissociative reactions show higher barriers and will not be relevant for FeS reactivity when exposed to solvent. These hydrolysis mechanisms may help to explain the stability and catalytic mechanisms of FeS clusters of multiple sizes and proteins</div><div><br></div>

REMOVAL OF HEAVY METAL Cr (II), Ni (II), Cu (II), Zn (II), Cd (II), Pb (II) IONS FROM AQUEOUS SOLUTION BY MENTHA PIPERITA EXTRACT

2020 ◽  
pp. 15-20
Author(s):  
Ersin Yucel ◽  
Mine Yucel
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
High Efficiency ◽  
Correlation Coefficients ◽  
Langmuir Model ◽  
Mentha Piperita ◽  
Freundlich Model ◽  
Biosorption Capacity ◽  
Peppermint Extract ◽  
The Stability

In this study, the usage of the peppermint (Mentha piperita) for extracting the metal ions [Mg (II), Cr (II), Ni (II), Cu (II), Zn (II), Cd (II), Pb (II)] that exist at water was investigated. In order to analyze the stability properties, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were used at removing the metal ions and the highest correlation coefficients (R2) were obtained at Langmuir isotherm. Therefore, it is seen that the Langmuir model is more proper than the Freundlich model. However, it was found that the correlation coefficients of removing Ni and Cd is higher at Freundlich model than Langmuir and low at Dubinin-Radushkevich isotherm. It is established that the biosorption amount increase depends on the increase of biosorbent and it can be achieved high efficiency (95%) even with small amount (0.6 mg, peppermint extract) at lead ions. It is also determined that the peppermint extracted that is used at this study shows high biosorption capacity for metal ions and can be used for immobilization of metals from polluted areas.

Reactions in Activated Peroxide Systems and their Influences on Bleaching Performance

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiaoyan Wang ◽  
Jinmei Du ◽  
Changhai Xu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Energy Efficiency ◽  
Textile Industry ◽  
High Energy ◽  
Side Reactions ◽  
Competitive Reactions ◽  
High Energy Efficiency ◽  
Hydrolysis Of ◽  
Bleach Activators

Abstract:: Activated peroxide systems are formed by adding so-called bleach activators to aqueous solution of hydrogen peroxide, developed in the seventies of the last century for use in domestic laundry for their high energy efficiency and introduced at the beginning of the 21st century to the textile industry as an approach toward overcoming the extensive energy consumption in bleaching. In activated peroxide systems, bleach activators undergo perhydrolysis to generate more kinetically active peracids that enable bleaching under milder conditions while hydrolysis of bleach activators and decomposition of peracids may occur as side reactions to weaken the bleaching efficiency. This mini-review aims to summarize these competitive reactions in activated peroxide systems and their influence on bleaching performance.

Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

1983 ◽  
Vol 29 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
M W McGowan ◽  
J D Artiss ◽  
B Zak
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Amniotic Fluid ◽  
Enzymatic Reaction ◽  
Detergent Solution ◽  
Enzymatic Determination ◽  
Red Color ◽  
Hydrolysis Of ◽  
Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

The Hydrolysis of Sodium Polyphosphates

1971 ◽  
Vol 26 (6) ◽  
pp. 543-545
Author(s):  
Leopoldo J. Anghileri ◽  
Esther S. Miller
Keyword(s):  
Aqueous Solution ◽  
Slow Reaction ◽  
Linear Variety ◽  
The Cross ◽  
Hydrolysis Of

The hydrolysis of 32P-sodium polyphosphates (linear and cross-linked) in aqueous solution has been studied. The radiometric determinations indicate that the ortho-phosphate formation is a slow reaction, and that the amount formed by the linear variety is higher than that produced by the cross-linked form. There is a significant formation of metaphosphates during the hydrolysis of the cross-linked polyphosphate which is missing or at least reduced to a much lesser extent in the case of the linear polyphosphate.

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