Substitution reactions on arsenic(V). The formation and hydrolysis of pentaamminearsenatocobalt(III) in aqueous solution

1973 ◽  
Vol 26 (9) ◽  
pp. 1877 ◽  
Author(s):  
TA Beech ◽  
NC Lawrence ◽  
SF Lincoln
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Bond Formation ◽  
The Other ◽  
Substitution Reactions ◽  
Rate Law ◽  
Hydrolysis Of ◽  
Hydrolysis Reactions

The formation of Co(NH3)5HAsO4+ and Co(NH3)5H2AsO42+ conforms to the rate law: ����������� rate = [Co(NH3)5H2O3+](k-1[HAsO42-]+k-2[H2AsO4-]) where k-1 = (11�1)x10-2 l. mol-1 s-1 and k-2 = (120�15)x10-4 l. mol-1 s-1 at 295 K and unit ionic strength. The hydrolysis of the arsenato complex conforms to the rate law: ������ rate = [total arsenato complex](Ka2k1+k2[H+]+k3[H+]2)(Ka2+[H+])-1 where k1 = (290�15)x10-7s-1, k2 = (408�20)x 10-6 s-1, k3 = (670�34)x10-3 l. mol-1 s-1, and pKa2 = 3.30�0.05 at 295 K and unit ionic strength. The formation and hydrolysis reactions proceed through bond formation and cleavage between oxygen and arsenic. The mechanisms of the reactions characterized by k1 and k-1 are considered to be associative substitutions on arsenic(v), but the mechanisms of the other reactions are less certain.

The hydrolysis of halogenopentamminechromium(III) complexes

1967 ◽  
Vol 20 (5) ◽  
pp. 893 ◽  
Author(s):  
SC Chan ◽  
KY Hui
Keyword(s):  
Bond Formation ◽  
The Other ◽  
Nucleophilic Substitutions ◽  
Hydroxide Ion ◽  
Solvent Water ◽  
Hydrolysis Of

The Croup Replacement Factors (G.R.F.) of halogens in nucleophilic substitutions of halogenopentamminechromium(III) complexes both by solvent water and by hydroxide ion have been compared with the corresponding data available for the analogous cobalt(III) cations. Although reactions in the latter system are typical SN2 processes with concurrent bond formation and fission, the mechanism of substitutions in halogenopentamminechromium(III) complexes depends on the nature of the halogen, being bimolecular for the fluoro and unimolecular for the other halogeno cations. The kinetic results are discussed partly along lines similar to those employed for the interpretation of organic nucleophilic substitutions.

scholarly journals Vanadium(III) binding strengths of small biomolecules

2005 ◽  
Vol 77 (9) ◽  
pp. 1583-1594 ◽  
Author(s):  
Péter Buglyó ◽  
Eszter Márta Nagy ◽  
Imre Sóvágó
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Ionic Strength ◽  
Metal Ion ◽  
Donor Ligands ◽  
Spectroscopic Techniques ◽  
Hydroxo Complexes ◽  
Similarities And Differences ◽  
Small Biomolecules ◽  
Hydrolysis Of

The hydrolysis of vanadium(III) and the complex formation reactions between V(III) and weakly coordinating [glycine (GLY), DL-aspartic acid (ASP), D-penicillamine (PEN), DL-histidine (HIS)] or strongly coordinating [N,O] donor [picolinic (PIC) or 6-methylpicolinic acid (MePIC)] and [O,O] donor [maltol (MALT), 1,2-dimethyl-3-hydroxy-4-(1H)-pyridinone (DHP), tiron (TIR)] ligands were studied at 25.0 °C and an ionic strength of 0.20 M (KCl) in aqueous solution using combined pH-potentiometric and UV-vis spectroscopic techniques. Although some interaction between the amino acids and V(III) was found, we could not obtain reliable models for these systems owing to the intensive hydrolysis of the metal ion and the formation of polynuclear hydroxo complexes. With pyridine carboxylates or [O,O] donor ligands 1:1, 1:2 (in the latter case, also 1:3 species) were found to be present as major complexes in solution. The similarities and differences in binding V(III) by these ligands are discussed.

Kinetics and mechanisms of oxidations by metal ions. Part VIII. Oxidation of n-propanol by aquomanganese(III) ions

1987 ◽  
Vol 65 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Mahendra Mehta ◽  
Ratan R. Nagori ◽  
Raj N. Mehrotra
Keyword(s):  
Ionic Strength ◽  
Metal Ions ◽  
Equilibrium Constant ◽  
Thermodynamic Parameters ◽  
The Other ◽  
Constant Ionic Strength ◽  
Rate Law

The oxidation of n-propanol by aquomanganese(III) ions in perchlorate medium of constant ionic strength (4 mol dm−3, NaClO4) is described by the rate law [i] which is based on the consideration of the reactions [ii]–[ix].[Formula: see text]A further analysis of the rate law in terms of the results indicated that MnOH2+ (aq) is the major oxidant. The values of the equilibrium constant (β1) and rate determining constant (k1) are reported together with the associated thermodynamic parameters. The values of the other constants, k, Ka, and β, could not be determined though an assumption was made that β ≈ β1.

scholarly journals A study of factors influencing hydration of sodium hyaluronate from compressibility and high-precision densimetric measurements

1983 ◽  
Vol 213 (2) ◽  
pp. 363-369 ◽  
Author(s):  
A Davies ◽  
J Gormally ◽  
E Wyn-Jones ◽  
D J Wedlock ◽  
G O Phillips
Keyword(s):  
Aqueous Solution ◽  
Hyaluronic Acid ◽  
Ionic Strength ◽  
Pure Water ◽  
Bond Formation ◽  
Sodium Hyaluronate ◽  
Type Solution ◽  
Salt Form ◽  
Density Measurements ◽  
Factors Influencing

A study of the factors influencing the hydration of the biopolymer hyaluronic acid was made by compressibility and density measurements. The factors investigated were the hydration changes on glycosidic bond formation, and also the influence of counterion type, solution ionic strength and temperature. The results indicate that, with this biopolymer, the hydration of the glucuronate residue is significantly more than that of the N-acetylglucosamine residue, and further that the biopolymer is less hydrated than the sum of its component monosaccharide residues. Change of the counterion salt form of this polyelectrolyte from univalent to bivalent counterion type (Na+ to Ca2+) leads to a small though significant increase in the total hydration sheath surrounding the polymer. An increase in the background ionic strength of the solvent leads to a quantifiable lowering of the hydration of the polymer at physiological ionic strength compared with its value in salt-free aqueous solution. A decrease in hydration with increase in temperature in the range 20-50 degrees C is the opposite of previous reports, and was observed when the polymer was dissolved both in pure water and in 0.15 M-NaCl.

Kinetics of oxidation of nitrite by hypochlorite ions in aqueous basic solution

1976 ◽  
Vol 54 (21) ◽  
pp. 3401-3406 ◽  
Author(s):  
J. M. Cachaza ◽  
J. Casado ◽  
A. Castro ◽  
M. A. López Quintela
Keyword(s):  
Ionic Strength ◽  
Initial Step ◽  
Activation Energies ◽  
The Other ◽  
Basic Solution ◽  
Unimolecular Decomposition ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Kinetics Of

The kinetics of oxidation of nitrite to nitrate by hypochlorite ions in aqueous basic solution [Formula: see text] have been studied using a dynamic spectrophotometric technique. The rate law is[Formula: see text]At 298.0 K and ionic strength 0.40 M, d = (3.4 ± 0.2) × 10−8 mol l−1 s−1 and e = (2.8 ± 0.2) × 10−6 s−1. The associated activation energies are 56 ± 3 and 61 ± 3 kJ mol−1 respectively. A mechanism is proposed involving the reversible initial step:[Formula: see text]with the NO2Cl undergoing two parallel subsequent reactions, one a unimolecular decomposition and the other an attack by NO2− on NO2Cl.

Model Reactions for the Degradation of DNA-4′ Radicals in Aqueous Solution. Fast Hydrolysis of α-Alkoxyalkyl Radicals with a Leaving Group in β-Position Followed by Radical Rearrangement and Elimination Reactions

1982 ◽  
Vol 37 (11-12) ◽  
pp. 1205-1227 ◽  
Author(s):  
Günter Behrens ◽  
Günther Koltzenburg ◽  
Dietrich Schulte-Frohlinde
Keyword(s):  
Aqueous Solution ◽  
Radical Cations ◽  
Cyclic Ethers ◽  
Γ Irradiation ◽  
A Value ◽  
Leaving Group ◽  
Catalyzed Reactions ◽  
Hydrolysis Of ◽  
Model Reactions ◽  
Hydrolysis Reactions

Abstract α-Alkoxyalkyl radicals with a leaving group L = Cl or OCOCH3 in β-position are produced by H-abstraction from the corresponding saturated substrates by ·OH, SO·4- or (CH3)3CO· radicals. From ESR spectroscopic observations it is concluded that in aqueous solution at pH 5 -9 the following fast hydrolysis reactions take place: The rate constants of these reactions and for the hydrolysis of CH3O-ĊH-CH2Cl are k ≥ 106 s-1, whereas the rate constant for CH3O-ĊH-CH2OCOCH3 was determined to be ≈ 2 × 103 s-1 at room temperature. The radicals with L = Cl cannot be scavenged by O2 which fact leads to a value of k ≥ 2 × 10-7 s-1. α-Alkoxyalkene radical cations are assumed as intermediates in the hydrolysis reactions. The radicals with L = OCOCH3 and the radical CH3O--ĊH-CH2Cl are observable in acetone solution ESR spectroscopically. In aqueous solution at pH below 3 proton catalyzed reactions are observed by ESR spectroscopy: Radicals resulting from H-abstraction at the CH3O-groups of the substrates or at the 5-positions of the cyclic ethers are also observed. The ESR parameters and the pH-ranges of existence of the above radicals are given. Support of the reported reactions comes from quantitative analysis of stable products such as H+, Cl- or CH3OH after 60Co-γ-irradiation of N2O saturated aqueous solutions of the substrates. The behaviour of the radicals is used as a model to describe a modified version of the degradation of DNA-4′ radicals in aqueous solution in the absence of oxygen.

Solubility of B-Nb2O5 and the Hydrolysis of Niobium(V) in Aqueous Solution as a Function of Temperature and Ionic Strength

2010 ◽  
Vol 39 (2) ◽  
pp. 197-218 ◽  
Author(s):  
C. Peiffert ◽  
C. Nguyen-Trung ◽  
D. A. Palmer ◽  
J. P. Laval ◽  
E. Giffaut
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Hydrolysis Of

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

Sign in / Sign up

Export Citation Format

Share Document