Presence Of Sulfate Research Articles

Kinetics of Hydrochloric Acid Oxidation by Cerium(IV) in the Presence of Sulphate Ions

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Semi-micro determination of azo and nitroso compounds and quinones with vanadium(II) sulphate

Semi-micro methods for the determination of azo and nitroso compounds and quinones with vanadium(II) sulphate have been described. About 100% excess of vanadium(II) sulphate is added in presence of sodium acetate and the excess of vanadium(II) is determined by titrating with iron(III) sulphate in presence of Neutral Red, Phenosafranine or Safranine-T as internal indicator. Results are accurate to less than ± 1%.

Determination of sulfate in presence of phosphate, arsenate, and other ions. Part II

Abstract Sulfate ions are titrated with barium chloride in presence of ammonium chloride, ammonia, eriochrome black-T, and magnesium EDTA complex. Alkaline earth interference is avoided with EDTA, and iron and aluminum masked with DCyTA. After sequestration of cations, phosphate and arsenate may be titrated with magnesium chloride. Finally, sulfate titration is carried out in the same solution with barium chloride.

Natural Activators for Liver Fructose 1,6-Diphosphatase and the Reversal of Adenosine 5′-Monophosphate Inhibition by Muscle Phosphofructokinase

1. The addition of a chelating agent was necessary in order to obtain maximal activity of rabbit liver fructose 1,6-diphosphatase at neutral pH. All attempts to demonstrate that this 10-fold or greater activation was merely due to the removal of trace heavy metal contaminants have been negative. 2. A naturally occurring material has been found in rabbit liver supernatant which produces a similar increase in enzymatic activity. Properties of the activator may be summarized as follows: (a) it is nondialyzable and destroyed by crystalline Bacillus subtilis proteolytic enzyme, and therefore it is probably a protein; (b) it can be precipitated at pH 6 and redissolved at pH 7.8; (c) it is unaffected by either p-mercuribenzoate or N-ethylmaleimide; (d) it is readily converted to aggregates upon purification. A very high concentration of activator was found in extracts of Novikoff hepatoma. 3. Purification of the muscle activator of liver fructose 1,6-diphosphatase paralleled phosphofructokinase activity. Twice recrystallized rabbit muscle phosphofructokinase activated rabbit liver fructose 1,6-diphosphatase 4-fold and both prevented and reversed the specific inhibition of the enzyme by adenosine 5′-monophosphate. Both phenomena were very specific for phosphofructokinase. The reversal of inhibition appears to be due to protein-protein interaction. Addition of adenosine 5′-triphosphate to this system counteracted the inhibition reversal. Similar results have been found with rabbit muscle fructose 1,6-diphosphatase. 4. Dissociation of muscle phosphofructokinase into active subunits of molecular weights 235,000 and 125,000 has been observed upon sucrose density gradient centrifugation in the presence of sulfate ions and liver supernatant (pH 6). It is suggested that these may be the active dimer and monomer, respectively, of phosphofructokinase. 5. The molecular and physiological significance of these observations is discussed.

Polarographic Behavior of Hydrogen Peroxide in the Presence of Sulfate Ion

Polarographic Behavior of Hydrogen Peroxide in the Presence of Sulfate Ion

Studies on Some New Indazole and Benzimidazole Derivatives

AbstractAlkylation of 5‐nitroindazole (I) with dimethyl sulphate and/or diethyl sulphate in presence of sodium hydroxide yields mixtures containing more 2‐alkylated than 1‐alkylated products. The action of diazomethane on 5‐nitro (I) and 6‐nitro‐indazole (IV) was investigated. Reduction of nitroindazoles with hydrogen on Pd/charcoal proceeds smoothly. The synthesis of several new benzimidazole and indazole dye intermediates is also described.

Vulcanization of Elastomers. 40. Vulcanization of Natural Rubber and Synthetic Rubber with Sulfur in Presence of Sulfenamides. III

Abstract Vulcanization of natural rubber with sulfur was studied in presence of six sulfenamides, to determine the effect of the chemical constitution of the sulfenamide on sulfur decrease and on crosslinking. The results can be condensed as follows: (1) The kinetics of sulfur disappearance is in every respect qualitatively independent of the chemical constitution of the sulfenamide. (2) For the sulfenamides investigated, the smallest and largest rate constants for sulfur decrease differed only by a factor of two. (3) Greater differences are encountered in the induction times for sulfur decrease and for crosslinking. The latter are notably longer than those for sulfur disappearance. (4) The same activation energy, 23 kcal/mole, is derived from the temperature dependence of the induction times for all the sulfenamides. (5) The dissociation of sulfenamides in solution and their reaction with mercaptobenzothiazole were investigated further. The results provide the basis for a proposed reaction mechanism, which is presented in detail and can account for a number of the features typical of sulfenamide-accelerated vulcanization. (6) The drop in sulfur concentration goes at practically the same rate, if one introduces, instead of N, N-dicyclohexyl-2-benzothiazolesulfenamide, the corresponding ammonium mercaptide in equimolar concentration.

Vulcanization of Elastomers. 39. Vulcanization of Natural and Synthetic Rubbers by Sulfur and Sulfenamides. II

Abstract The dependence of the kinetics of vulcanization of natural rubber by sulfur in presence of N-cyclohexyl-benzothiazolylsulfenamide (CHBS) on temperature and for varied molar ratios of accelerator and sulfur was more exactly investigated. 1. Although the vulcanization of natural rubber accelerated with N-cyclohexyl-benzothiazolylsulfenamide with conventional experimental conditions is characterized by very long induction times, nevertheless—as also for other accelerated vulcanization reactions—sulfur decrease follows a time law with nt&amp;lt;1 and the activation energy, as in other cases, is calculated to be 29 kcal/mole. 2. The value nt=0.6 is found for the exponent of the time law, independent of temperature and concentration of reactants. 3. The concentration dependence of the rate of sulfur decrease under conditions of constant sulfur content and increasing sulfenamide concentration is found to be consistent with catalysis by an intermediate compound. 4. The actual accelerator may be essentially cyclohexylammonium-benzothiazoylmercaptide. 5. The temperature and concentration dependence of the induction periods for sulfur decrease and crosslinking were investigated. The course of crosslinking with reaction time, which is characterized by strong reversion, is discussed.

Influence of pH and sulphate content of the solution on the corrosion of graphite anodes in alkali chloride electrolysis

Graphite anode corrosion exhibits a maximum at neutral pH values. This is explained as the result of two opposing factors: the amount of oxygen evolved per unit time and the activity of the anodic oxygen.The presence of sulphate ion in the solution increases graphite anode corrosion strongly in concentrated chloride solutions (200 g/l. NaCl) but not noticeably in dilute solutions (50 g/l. NaCl). Specific adsorption of sulphate ion and the swelling of graphite are suggested as reasons for the detrimental effect of sulphate.

Existence d'un mécanisme de transport de la chitinase a travers les membranes cellulaires

Abstract The effect of various substances has been studied on the secretion of chitinase (chitin glycanohydrolase, EC 3.2.1.14) by the isolated gastric mucosa of Reptilia and Amphibia. Our results show that N -methylpyridinium-2-aldoxime iodide, the antidiuretic hormone, glycine and DNP are without effect on the secretory process. The electrical potential difference existing spontaneously between the two faces of the epithelium is also unaffected except in the case of DNP which abolishes it. On the contrary, monoiodoacetate and sulfate ions inhibit the secretion of chitinase, and remove the electrical potential difference. In the presence of sulfate ions the potential difference is sometimes reversed. When the potential difference is short-circuited by means of an external electromotive force, the secretion is not modified. Consequently, there is no direct relationship between potential difference and chitinase secretion. One way of explaining the effect of monoiodoacetate is to postulate an action on the sulfhydryl group of the membrane. From our results it is reasonable to suggest that the secretion of chitinase depends on a mechanism involving the formation of a complex between the enzyme and some structural element of the membrane.

Titrimetric Determination of Semimicro Amounts of Sulfate in Presence of Phosphate.

Titrimetric Determination of Semimicro Amounts of Sulfate in Presence of Phosphate.

Electrolytically Regenerated Manganic Sulfate for the Oxidation of Aromatic Hydrocarbons: II . Oxidation of Xylenes to Tolualdehydes

A two‐stage process for the oxidation of xylenes to tolualdehydes is described which consists of the oxidation of manganous sulfate to manganic sulfate in the cell and reacting the manganic sulfate obtained with xylene outside the cell. The reason for low current efficiency for the in‐cell oxidation is explained on the basis of anode potential measurement. Measurement of the oxidation potential of manganic sulfate in presence of xylene indicates that the steady potential attainable during the reaction makes it possible to control the oxidation of xylene to tolualdehyde. A large laboratory cell is described.

Iron(II) + Iron(III) Isotope Exchange in Presence of Sulfate Ions

Iron(II) + Iron(III) Isotope Exchange in Presence of Sulfate Ions

Ferrous-ferric redox reaction in the presence of sulphate ion

Ferrous-ferric redox reaction in the presence of sulphate ion

Stability of Lyophobic Sols

The adsorption of stabilising ion H+ has been determined for a precipitate of hydrous ferric oxide and that of SO4″ for the positively charged sol of hydrous ferric oxide during its coagulation as affected by potassium sulphate in presence of various non-electrolytes. The adsorption of both the stabilising and coagulating ions decreases in presence of ethyl alcohol and acetone, an increase is, however, observed in presence of glucose and urea. With gelatin at lower concentration the adsorption of both H+ and SO4″ decreases whilst the reverse is noticed at higher concentrations. It is concluded that the cutting down of the adsorption of either the stabilising or the coagulating ion cannot explain sensitisation or stabilisation.

The Thermal Decomposition of Tertiary Butyl Chloride in the Presence of Sulphur Hexafluoride

No acceleration of the gas-phase decomposition of tertiary butyl chloride at 284-309 �C occurs in the presence of sulphur hexafluoride. This behaviour contrasts with that of a variety of unimolecular decompositions probably occurring via triplet states where an extension of the simple theory of activation has been found necessary.

Stability of lyophobic sols

The adsorption of stabilising ion H+ has been determined for a precipitate of hydrous ferric oxide and that of SO4″ for the positively charged sol of hydrous ferric oxide during its coagulation as affected by potassium sulphate in presence of various non-electrolytes. The adsorption of both the stabilising and coagulating ions decreases in presence of ethyl alcohol and acetone, an increase is, however, observed in presence of glucose and urea. With gelatin at lower concentration the adsorption of both H+ and SO4″ decreases whilst the reverse is noticed at higher concentrations. It is concluded that the cutting down of the adsorption of either the stabilising or the coagulating ion cannot explain sensitisation or stabilisation.

On the reaction between cerium (IV) ions and peroxysulphuric acid

During cerimetric determination of solutions containing hydrogen peroxide and peroxysulfuric acid, the amount of peroxysulfuric acid consumed depends on the rate of titration. Since the same consumption occurs in the absence of hydrogen peroxide, the decomposition must be attributed to the reaction between cerium(IV) ions and peroxyaulfuric acid. Therefore, cerimetric titrations with ceric sulfate and ceric nitrate were investigated. The results showed that in the presence of sulfate ion, the amount of peroxysulfuric acid decomposed in one minute increases proportional to the concentration of Ce/sup 4+/ . The addition of Ce/sup 3+/ to the solution de creases the decomposition as a function of the ratio Ce/sup 4+//Ce/sup 3+/. The reaction between peroxysulfuric acid and Ce/sup 4+/ is more rapid in the presence of nitrate ions than sulfate ions. The reaction rate increases with the addition of Ce/sup 3/. (J.S.R.)

Vulcanization of Elastomers XV. The Vulcanization of Natural and Synthetic Rubber with Sulfur in Presence of Organic Bases (I)

Abstract The results obtained from preliminary kinetic studies of the vulcanization of natural rubber (NR) with sulfur in the presence of organic bases may be summarized as follows. 1) The change of concentration of sulfur with time during reaction with NR for an initial sulfur concentration of 2.5 g per 100 g of mixture follows a fractional reaction order, n, of 0.6 at all temperatures. This result and the findings of other authors suggest that the reaction of sulfur with rubber is autocatalytic. From the temperature dependence of the rate constant the activation energy is found to be 35.3 kcal. 2) In the presence of zinc oxide and with a similar initial sulfur concentration, the reaction is first order and the activation energy, namely 35.6 kcal, is practically the same. 3) In the presence of diphenylguanidine (DPG) during cure sulfur decrease is a reaction of fractional order, n=0.75, and the activation energy is 29.8 kcal. 4) For a given initial concentration of sulfur and at constant temperature the rate of sulfur decrease during vulcanization increases with rising DPG content and reaches a limiting value; i.e., the rate constant depends on DPG concentration. Also, for various base (DPG is basic) concentrations sulfur decrease is of various fractional orders, n=0.5…0.7, etc. 5) The influence of base on the rate of sulfur decrease is interpreted broadly as a case of intermediate-catalysis (Zwischenstoff-Katalyse). 6) Vulcanization with sulfur is unaffected by tertiary amines and secondary amines have only a slight effect. 7) Primary amines, depending on basic strength, are strong accelerators of the rate of sulfur decrease. 8) In the presence of organic bases (aromatic amines) other than DPG, sulfur decrease is of fractional order where n varies between 0.5 and 0.7.

Direct titration of potassium ferricyanide with hydrazine sulphate in presence of zinc sulphate determination of hydrazine

Operative conditions for direct titration of potassium ferricyanide solution with a solution of hydrazine sulphate which contains zinc sulphate are described. The results are comparable with those obtained by the standard iodate procedure. The chief advantages of the present method of estimating hydrazine are (1) titration in slightly acidic medium and (2) no indicator is required. Determination of substituted hydrazines, hydroxylamine and other reducing substances on similar lines is suggested.