Kinetics of Spontaneous Hydrolysis of O-(2,2-Dimethylcyclopentyl)-methylfluorophosphonate and of Hydrolysis During Constant pH Value of the Reaction Medium

2003 ◽  
Vol 178 (7) ◽  
pp. 1521-1540 ◽  
Author(s):  
Boban Ceković ◽  
Bratislav Jovanović ◽  
Zoran Luković
Keyword(s):  
Ph Value ◽  
Reaction Medium ◽  
Constant Ph ◽  
Spontaneous Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Inhibition of the elastase of Pseudomonas aeruginosa by N.alpha.-phosphoryl dipeptides and kinetics of spontaneous hydrolysis of the inhibitors

Biochemistry ◽  
1984 ◽  
Vol 23 (12) ◽  
pp. 2766-2772 ◽  
Author(s):  
Louis Poncz ◽  
Thomas A. Gerken ◽  
Dorr G. Dearborn ◽  
Damian Grobelny ◽  
Richard E. Galardy
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Spontaneous Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Effect of Vapor Pressure of H2O on the Formation of Nano-Crystalline TiO2 Ultrafine Powders

1999 ◽  
Vol 581 ◽  
Author(s):  
K. R. Lee ◽  
S. J. Kim ◽  
J. S. Song ◽  
S. Park
Keyword(s):  
Vapor Pressure ◽  
Reaction Rate ◽  
Ph Value ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Precipitation Process ◽  
Nano Crystalline ◽  
Natural Decrease ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of

ABSTRACTMono-dispersed TiO2 ultrafme particles with diameters 40-400nm were obtained from aqueous TiOCl2 solution with 0.67M Ti4+ concentration prepared diluting TiCl4 by homogeneous precipitation process in the ranges of 17-230°C. With the spontaneous hydrolysis of TiOCl2, which means the natural decrease of pH value in the aqueous solution, all mono-dispersed precipitates were crystallized with the anatase or rutile TiO2 phase. TiO2 precipitate with the pure rutile phase was fully formed at the temperatures below 65 °C, not involving the evaporation of H2O, and above 155 °C, which were available by suppressing it. TiO2 precipitate with rutile phase including a small amount of the anatase phase started to be formed in the intermediate temperatures above 70 °C showing the full formation of the anatase above 95 °C under the free evaporation of H2O. However, in the case of completely suppressing H2O evaporation at the temperatures above 70°C, TiO2 precipitate with anatase phase was fully transformed into the precipitate with the rutile phase by the vapor pressure of H2O. Therefore, the formation of TiO2 precipitates with the rutile phase around room temperature would be caused due to the existence of the capillary pressure between the agglomerated needle-shaped particles or the ultrafme clusters, together with the slow reaction rate.

Alkaline hydrolysis of monomethyl esters of maleic and fumaric acids

1983 ◽  
Vol 48 (5) ◽  
pp. 1305-1313
Author(s):  
Petr Komadel ◽  
Vladislav Holba ◽  
Štefan Truchlik
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Alkaline Hydrolysis ◽  
Reaction Medium ◽  
Measured Data ◽  
Interaction Energies ◽  
Mutual Compensation ◽  
Experimental Activation Energy ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of maleic and fumaric acids monomethyl esters were studied as function of the temperature, ionic strength, and relative permittivity of the reaction medium. Electrostatic and nonelectrostatic contributions of the interaction energies of reacting species were calculated from the measured data and compared with the experimental activation energy values. The dependence of the rate constant on the temperature brings an evidence for the mutual compensation of the electrostatic and nonelectrostatic effects.

scholarly journals ENZYME KINETICS IN A HISTOCHEMICAL SYSTEM

1958 ◽  
Vol 6 (6) ◽  
pp. 431-434 ◽  
Author(s):  
EARL P. BENDITT ◽  
MARGARET ARASE
Keyword(s):  
Chemical Kinetics ◽  
Enzyme System ◽  
The Other ◽  
End Point ◽  
Straight Line ◽  
Spontaneous Hydrolysis ◽  
Fixed Quantity ◽  
Set Up ◽  
Kinetics Of ◽  
Hydrolysis Of

Modification of the Lineweaver and Burk method of handling the chemical kinetics of an enzyme system has been made to suit the histochemical conditions. Thus if the reaction is allowed to run to some fixed quantity of end point 1/v becomes proportion to the time necessary to reach this end point. In practice serial dilutions of substrate and serial increments in time of incubation are set up. Slides are then separated under the microscope into groups of equal intensity. A plot of 1/[S] v.s. t fits a straight line as expected. Competition between two substrates, one chromogenic the other non-chromogenic, can be demonstrated. One source of deviation from the theoretical due to spontaneous hydrolysis of substrate has been recognized and can be accounted for.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

Belousov–Zhabotinskii type oscillation reaction with glycerol and kinetics of reactions between the system components

1987 ◽  
Vol 52 (10) ◽  
pp. 2375-2382 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Peter Ševčík
Keyword(s):  
Oscillation System ◽  
Chemical Oscillations ◽  
Oscillation Reaction ◽  
Reaction Solution ◽  
System Components ◽  
Probable Source ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Type Oscillation

Glycerol causes chemical oscillations in Belousov-Zhabotinskii reaction in a closed system as well as in a reaction solution bubbled with nitrogen. Since the oxidation of glycerol with bromate ions does not proceed autocatalytically and bromine in the oxidation state 0 or +1 in the absence of light does not react with glycerol, hydrolysis of bromine is the probable source of bromide ions in the studied oscillation system.

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.

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