EFFECT OF CHANGING pH UPON THE RATE AND MECHANISM OF DECARBOXYLATION OF SUBSTITUTED ANTHRANILIC ACIDS

1965 ◽  
Vol 43 (11) ◽  
pp. 3080-3094 ◽  
Author(s):  
G. E. Dunn ◽  
P. Leggate ◽  
I. E. Scheffler
Keyword(s):  
Ionic Strength ◽  
Aromatic Ring ◽  
Maximum Rate ◽  
The Other ◽  
Constant Ionic Strength ◽  
Ionization Constants ◽  
Anthranilic Acids ◽  
Isoelectric Ph

The ionization constants of 4-methoxyanthranilic acid have been determined spectrophotometrically in water at 60 °C and ionic strength 0.10. The variation in rate of decarboxylation with varying pH at constant ionic strength has been measured at 90 °C with 4-methylanthranilic acid and at 60 °C with 4-methoxyanthranilic acid. With each acid the maximum rate occurs at a pH about 2 units less than the isoelectric pH. To account for these results it is necessary to postulate an equilibrium between at least two intermediates formed by protonation of the 1-position of the aromatic ring. One of these must be formed from the anion and the other(s) by protonation of neutral acid and (or) zwitterion.

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.

Adsorption of chlorate and bromate ions on mercury electrodes from constant ionic strength solutions

1988 ◽  
Vol 85 ◽  
pp. 523-527
Author(s):  
M.M. Zuleika ◽  
Palhares SILVA ◽  
Ernesto Rafael GONZALEZ ◽  
Luis Alberto AVACA ◽  
Artur de Jesus MOTHEO
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength ◽  
Mercury Electrodes

Endo-D-galacturonanase immobilized by adsorption on porous polyethyleneterephthalate

1982 ◽  
Vol 47 (10) ◽  
pp. 2716-2723 ◽  
Author(s):  
Lubomíra Rexová-Benková ◽  
Jiřina Omelková ◽  
Vladimír Kubánek
Keyword(s):  
Ionic Strength ◽  
High Stability ◽  
Relative Activity ◽  
Operational Stability ◽  
The Other ◽  
Fixation Strength ◽  
Action Pattern ◽  
Salt Solutions ◽  
Buffer Solution ◽  
Degradation Degree

Endo-D-galacturonanase of Aspergillus sp. was irreversibly adsorbed on polyethyleneterephthalate in an acetate 0.1 mol l-1 buffer solution of pH 4.2. Immobilization of the enzyme resulted in lowering of its activity, the measure of which depended on the amount of the enzyme fixed on the carrier. The highest relative activity (42.4%) had the preparation containing 5.25 mg of the enzyme per 1 g of the carrier. The velocity and intensity of the sorption of the enzyme depended on the ionic strength of the medium, whilst pH, on the other hand, was of no influence. Endo-D-galacturonanase immobilized in a 0.1 mol l-1 buffer was characteristic a) of its fixation strength in salt solutions of various ionic strength and pH, in a 3 mol l-1 guanidine solution, and also in sodium pectate and pectin solutions, b) of its high stability during a long-lasting storage at 4 °C, c) of its operational stability. The immobilization led to a partial change of the action pattern onto the high-molecular substrate, manifested in lowering the decrease of viscosity to degradation degree ratio.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

Filtration by superficial and deep glomeruli of normovolemic and volume-depleted rats

1986 ◽  
Vol 250 (1) ◽  
pp. F86-F91
Author(s):  
R. V. Pinnick ◽  
V. J. Savin
Keyword(s):  
Basement Membrane ◽  
Maximum Rate ◽  
Rate Of Change ◽  
The Other ◽  
Membrane Area ◽  
Morphometric Analyses ◽  
Three Samples ◽  
Glomerular Size ◽  
Glomerular Ultrafiltration

We measured glomerular ultrafiltration coefficient (Kf) of isolated superficial (S) and deep (D) glomeruli of normovolemic and volume-depleted rats. Filtration was induced in vitro, and Kf was calculated from the maximum rate of change in glomerular size. Basement membrane area (A) for each glomerulus was estimated from morphometric analyses, and glomerular capillary hydraulic conductivity (Lp) was calculated by the formula Lp = Kf/A. Kf of S and D glomeruli of normovolemic rats were 2.98 +/- 0.98 and 4.25 +/- 0.07 nl . min-1 . mmHg-1, respectively. In hypovolemic rats, Kf of S glomeruli fell by approximately 50% to 1.52 +/- 0.14 nl . min-1 . mmHg-1 (P less than 0.001), whereas Kf of D glomeruli remained unchanged at 4.28 +/- 0.10 nl . min-1 . mmHg-1. Lp, calculated using the peripheral capillary area, averaged 1.98 +/- 0.09 and 1.98 +/- 0.06 microliter . min-1 . mmHg-1 . cm-2 in S and D glomeruli of normovolemic rats and 1.89 +/- 0.11 microliter . min-1 . mmHg-1 . cm-2 in D glomeruli of hypovolemic rats. Lp of S glomeruli of volume-depleted rats (0.90 +/- 0.03 microliter . min-1 . mmHg-1 . cm-2) was lower than in any of the other three samples. Mild hypovolemia causes the Kf of S glomeruli to decline, whereas Kf of D glomeruli remains constant. The decrease in Kf occurs without an alteration in capillary area and is most likely due to a decrease in Lp.

Speciation of protactinium(V) at tracer scale

2009 ◽  
Vol 97 (7) ◽  
Author(s):  
Claire Le Naour ◽  
M. V. Di Giandomenico ◽  
Y. Zhao ◽  
M. Mendes
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Distribution Coefficient ◽  
Systematic Study ◽  
Chelating Agent ◽  
Constant Ionic Strength ◽  
Diethylene Triamine ◽  
Sulphate Chloride

AbstractSolvent extraction in the conditions of tracer scale chemistry was used to study protactinium(V) complexation with sulphate, chloride, oxalate and diethylene-triamine-pentaacetate. Extraction experiments were conducted using the chelating agent thenoyltrifluoroacetone (TTA) in toluene at constant ionic strength and temperature. Information on the species involved in partition equilibria relative to protactinium(V) complexation were deduced from a systematic study of the variations of distribution coefficient of Pa(V) as function of ligands, protons and TTA concentration.

scholarly journals Effects of Imprinting and Water Activity on Transesterification and Thermostability with Lipases in Ionic Liquid

2021 ◽  
Vol 35 (1) ◽  
pp. 57-63
Author(s):  
M. Matsumoto ◽  
K. Nakao ◽  
Y. Tahara
Keyword(s):  
Ionic Liquid ◽  
Water Content ◽  
Benzyl Alcohol ◽  
Vinyl Acetate ◽  
Water Activity ◽  
Maximum Rate ◽  
The Other ◽  
Organic Media ◽  
Catalytic Activities ◽  
Michaelis Constants

The effect of bio-imprinting and water activity on catalytic activities and the thermostability of lipases was investigated for transesterification using vinyl acetate and benzyl alcohol as substrates in ionic liquid, [Cnmim][PF6] (n=4,6,8), and benzene. The catalytic activities were enhanced by imprinting in benzene and [C4mim][PF6], and the relations between the transesterification activities and the water activity in both solvents were approximately bell shaped. The reactivity of the transesterification in benzene was higher than that in [C4<br /> mim][PF6]. The effects of water activity and imprinting on the kinetic parameters in [C4mim][PF6] were examined. Without controlling the water content, the values of Km,VA and Km,BA (Michaelis constants of vinyl acetate and benzyl alcohol, respectively) decreased, and the values of Vm (maximum rate) increased by imprinting. On the other hand, by controlling the water content in the organic media, the values of Vm, Km,VA, and Km,BA increased by imprinting. The activities of lipase in ionic liquid are more strongly affected by water activity and imprinting than those in benzene. We observed effects of water activity on thermostability but none from imprinting.

scholarly journals On the Nature of Bacterial Lag

1914 ◽  
Vol 14 (2) ◽  
pp. 215-241 ◽  
Author(s):  
William Jas. Penfold
Keyword(s):  
Maximum Rate ◽  
The Other ◽  
Water Culture ◽  
Rate Of Growth ◽  
Heat Stable ◽  
Other Hand ◽  
Parent Culture ◽  
Peptone Water ◽  
Effect On Growth

(1) If B. coli be subcultured into another sample of the same medium when growing at full pace, it will continue to grow at the same pace.(2) If the maximum rate of growth be interrupted by a short application of cold, growth will recommence without lag on the temperature being raised. If the cold be long continued, lag will tend to reappear.(3) Differences in the size of inoculum have practically no effect on lag in the case of large inoculums, in the case of small ones, on the other hand, diminution of the seeding has the effect of lengthening lag, and this lengthening effect is more marked the smaller the seedings become.(4) Lowering the temperature lengthens the lag. The effect is very similar to the effect on growth.(5) The older a parent culture (within limits) the longer the lag.(6) The length of lag varies with the medium even if adaptation has been arranged for beforehand.(7) Heat-stable products in B. coli cultures on peptone water have, in the case of overnight cultures, but little effect on lag.(8) After washing the bacteria for two hours with saline in order to remove possible inhibiting agents, it was found that the lag, on subculture, still occurred and was indeed slightly longer.(9) If a peptone water culture of B. coli be centrifuged, it is found that the few bacteria remaining in the supernatant commence to grow again at a quick rate but not without a period of lag.

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