Phosphato complexes of cobalt(III). III. Hydrolysis reactions in perchloric acid media

1968 ◽  
Vol 21 (1) ◽  
pp. 67 ◽  
Author(s):  
SF Lincoln ◽  
DR Stranks
Keyword(s):  
Perchloric Acid ◽  
Rate Constants ◽  
Intramolecular Hydrogen Bonding ◽  
Acid Media ◽  
Water Solvent ◽  
Rate Of Hydrolysis ◽  
Intramolecular Hydrogen ◽  
Hydrolysis Of ◽  
Protonated Complexes ◽  
Rate Behaviour

Rates of hydrolysis of phosphato complexes of oobalt(111) in perchloric acid media ranging from 10-3 to 11.4M have been measured by the rates of release of phosphate from 32P-labelled phosphato complexes. First-order rate behaviour is exhibited under all conditions and half-times range from hours to minutes within the range 45-70�. Bidentate phosphato complexes exhibit the same rates of hydrolysis as the corresponding monodentate complexes due to a rapid conversion of the bidentate into the monodentate form. Rate constants have been measured for three distinct protonated complexes (PI, P2, P3). At 60� these rate constants, expressed in the order of aquo-tetraammine, -penhammine, and ?bisethylenediamine complexes, are PI: 74.0, 1.20, 5.5 X 10-3 min-1; P2: 2.5, 1.20, 0.40 x 10-3 min-1; P3: 20.0, 9.0, 5.5 x 10-3 min-1. A tetraprotonated complex (P4) is incompletely generated even in 11.4M HClO4 where observed rate constants at 60� are 8.2, 3.4, 7.0 x 10-2 min-1 respectively. Intramolecular hydrogen bonding is considered important in the P1 and P2 species, especially in the cis-aquophosphato complexes. The rate of hydrolysis of P3 complexes is linearly dependent on the activity of the water solvent consistent with a mechanism involving SN2 attack of water at a cobalt(111) centre. The P4 complex is considered to hydrolyse via an SNICA mechanism.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

The proton affinities and deprotonation enthalpies of β-D-fructopyranose and α-L-sorbopyranose

1991 ◽  
Vol 69 (12) ◽  
pp. 1917-1928 ◽  
Author(s):  
Robert J. Woods ◽  
Walter A. Szarek ◽  
Vedene H. Smith Jr.
Keyword(s):  
Hydrogen Bonding ◽  
Oxygen Atom ◽  
Intramolecular Hydrogen Bonding ◽  
Hydroxyl Group ◽  
Proton Affinities ◽  
Naturally Occurring ◽  
Acid Catalyzed ◽  
Acids And Bases ◽  
Intramolecular Hydrogen ◽  
Hydrolysis Of

The proton affinities (PAs) and deprotonation enthalpies (DPEs) were calculated for the pyranoid forms of two naturally occurring sugars, D-fructose and L-sorbose. In both molecules the PAs of the primary hydroxyl group (HO-1), the anomeric hydroxyl group (HO-2), and the ring-oxygen atom (O-6) were calculated, as were the DPEs of HO-1 and HO-2. The stabilities of the conjugate acids and bases of these sugars are enhanced by the presence of intramolecular hydrogen bonding, a feature that is significant in explaining the differences in sweetness and the rates of mutarotation of the title compounds, as well as the differences in the rates of acid-catalyzed hydrolysis of ketopyranosides. Key words: proton affinity, deprotonation enthalpy, ab initio calculations, AM1, hexuloses.

The Hydrolysis of Bis(2-chloroethyl) Sulfide (Sulfur Mustard) in Aqueous Mixtures of Ethanol, Acetone and Dimethyl Sulfoxide

1993 ◽  
Vol 46 (3) ◽  
pp. 293 ◽  
Author(s):  
RI Tilley
Keyword(s):  
Transition State ◽  
Dimethyl Sulfoxide ◽  
Rate Constants ◽  
Charge Separation ◽  
Sulfur Mustard ◽  
Transition States ◽  
Aqueous Mixtures ◽  
Sulfide Sulfur ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The rate of hydrolysis of bis (2-chloroethyl) sulfide (sulfur mustard) in aqueous mixtures of ethanol, acetone and dimethyl sulfoxide has been measured and compared with previously reported values. Rate constants in water at 25°C for the two consecutive hydrolysis reactions undergone by sulfur mustard were estimated to be (2.93�0.15)×10-3 and (3.87�0.14)×10-3 s-1. Charge separation of 0.42 in the transition states was indicated together with significant solvation of the positive end of the transition state dipoles.

scholarly journals Properties of methyl acetimidate and its use as a protein-modifying reagent

1981 ◽  
Vol 193 (1) ◽  
pp. 245-249 ◽  
Author(s):  
A J Makoff ◽  
A D B Malcolm
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Effect Of Ph ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The rate of hydrolysis of the imido ester methyl acetimidate and its rate of amidination of denatured aldolase were investigated under different conditions of temperature, pH and ionic strength. Both rate constants increase greatly with temperature, whereas ionic strength has no effect on either. The effect of pH is more complex. Between pH 6.8 and 8.8 the rate of hydrolysis decreases and the rate of amidination increases. These results are discussed in terms of the reaction mechanisms involved.

THE EFFECT ON REACTION RATES CAUSED BY THE SUBSTITUTION OF C14 FOR C12: I. THE ALKALINE HYDROLYSIS OF CARBOXYL-LABELED ETHYL BENZOATE

1949 ◽  
Vol 27b (10) ◽  
pp. 807-812 ◽  
Author(s):  
William H. Stevens ◽  
Richard W. Attree
Keyword(s):  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Room Temperature ◽  
Reaction Rates ◽  
Ethyl Benzoate ◽  
Hydrolysis Rate ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

A study of the alkaline hydrolysis of C14 carboxyl-labeled ethyl benzoate has shown that the substitution of C14 for C12 changes the rate of hydrolysis of the ester. Ester molecules containing C14 hydrolyze at a slower rate than normal ester molecules. The ratio of the hydrolysis rate constants at room temperature has been found to be 0.86 ± 0.016.

Kinetics of acid-catalysed hydrolysis of the α and β Carbonato(4,7-dimethyltriethylenetetramine) cobalt(III) ions

1974 ◽  
Vol 27 (2) ◽  
pp. 269 ◽  
Author(s):  
DJ Francis ◽  
GH Searle
Keyword(s):  
Acid Hydrolysis ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Bond Cleavage ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Rate Laws ◽  
Kinetics Of ◽  
Hydrolysis Of

The synthesis and separation of the complexes α-[Co(dmtr)CO3] ClO4 and β-[Co(dmtr)CO3] C1O4,H2O (dmtr = 4,7-dimethyltriethylenetetramine or N,N'-bis(2-aminoethyl)-N,N'-dimethylethane-1,2-diamine) are described. The kinetics of the acid hydrolysis of both complexes, studied in perchloric acid at 25�C and μ = 1.0M (LiC1O4), follow rate laws of form -d[complex]dt=(k0 + k1[H+I)[complex] The values of ko and k1 for the K-complex are 1.0 x 10-3 s-1 and 1.8 x 10-2 1. mol-1 s-1 respectively, while for the β-complex the corresponding values are 3.6 x 10-5 s-1 and 5.6 x 10-4 1. mol-1 s-1. Comparisons of these rate constants with the values for similar carbonato(tetramine)cobalt(111) complexes previously studied suggest that the ko path could involve O-C bond cleavage in the present dmtr complexes. The values of the acid dissociation constants of dmtr,4HCl, determined by potentiometric titration, are 1.61, 5.86, 8.18 and 9.95.

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