THE MECHANISM OF THE ALCOHOLYSIS OF ALIPHATIC NITRITES: II. ACID-CATALYZED ALCOHOLYSIS OF 1-METHYLHEPTYL NITRITE

1961 ◽  
Vol 39 (4) ◽  
pp. 947-953 ◽  
Author(s):  
A. D. Allen ◽  
G. R. Schonbaum
Keyword(s):  
Reaction Rate ◽  
Chloride Ion ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Lithium Salts ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Low Concentrations ◽  
Acid Catalyzed ◽  
Asymmetric Carbon

The acid-catalyzed alcoholysis of 1-methylheptyl nitrite has been studied kinetically. The reaction rate is first order with respect to both the nitrite and the hydrogen ion concentration, and the reaction does not involve the asymmetric carbon center. Addition of lithium salts (chloride and perchlorate) indicates catalysis by chloride ion. Addition of water in low concentrations inhibits the reaction strongly. These results and the mechanism of the reactions are discussed in terms of the properties of the alcohols and the dissociation of the acid catalysts in the alcohols used.

Kinetics and Mechanism of Oxidation of Tin(II) by Hexachloroiridate(IV) in Aqueous Perchlorate Solutions

1992 ◽  
Vol 57 (2) ◽  
pp. 326-331 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Reaction Mechanism ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Mechanism Of Oxidation ◽  
Kinetics Of ◽  
Overall Kinetics

The kinetics of hexachloroiridate(IV) oxidation of tin(II) in aqueous perchlorate media at a constant ionic strength of 2.0 mol dm-3 have been studied spectrophotometrically. The reaction was found to follow second-order overall kinetics and first order with respect to each of the reactants. The results showed hydrogen ion dependence where the reaction rate increased with increasing hydrogen ion concentration. The activation parameters were evaluated and a tentative reaction mechanism has been discussed.

THE ELECTRODE POTENTIAL OF IRON IN RELATION TO HYDROGEN ION CONCENTRATION

1936 ◽  
Vol 14b (1) ◽  
pp. 31-40 ◽  
Author(s):  
J. W. Shipley ◽  
J. H. Shipley
Keyword(s):  
Electrode Potential ◽  
Chloride Ion ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Iron Electrode ◽  
General Corrosion ◽  
Citrate Buffer ◽  
Hydrogen Ion Concentration ◽  
Electrically Conducting ◽  
Ph Values

The electrode potential of iron immersed in phosphate, borate and citrate buffers of varying hydrogen ion concentration was measured, using a normal calomel electrode as the second half of the cell. Breaks in the potential of the iron electrode amounting to as much as 0.7 volts were found to occur at definite pH values for each series of buffers. The electrode exhibited an "initial" and "final" potential depending on the pH of the electrolyte and the time of immersion, the "final" value requiring several days to become established. The "final" break in the electrode potential of 0.74 volts in the pure phosphate buffer occurred between a pH of 3.1 and 4.0, that in the pure borate buffer, of 0.75 volts, occurred between a pH of 4.3 and 4.6, and in the pure citrate buffer, of 0.77 volts, between a pH of 10.1 and 10.9. The effect of chloride ion and de-aeration on the electrode potential was observed. It is suggested that the potential of the iron electrode is determined by the presence or absence of a non electrically conducting film or deposit on the iron, the formation of which is a function of the nature of the electrolyte and its hydrogen ion concentration. De-aeration apparently had no effect on the electrode potential, but the presence of chloride ion affected the establishing of the "final" potential and caused the break in voltage to appear irregularly at a much lower hydrogen ion concentration.At pH values below that at which the break in potential occurred, corrosion of the iron electrode was marked, and the electrode potential remained high, while, at pH values above the break, corrosion was virtually inhibited or confined to local spots on the electrode, and the electrode potential remained low. The presence of the chloride ion stimulated local corrosion and permitted general corrosion to proceed at a lower hydrogen ion concentration.

scholarly journals An Investigation of Some Aspects of the Coordination Chemistry of Synthetic Macroheterocyclic Ligands

2021 ◽  
Author(s):  
◽  
Peter Osvath
Keyword(s):  
Solid State ◽  
Rate Constant ◽  
Variable Temperature ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Dissociation ◽  
Ligand Field ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Chelate Rings

<p>The preparation of a range of fully saturated, unsubstituted pentaazamacrocycles is described. The macrocycles vary in ring size from fifteen to twenty members, and comprise every possible arrangement of dimethylene and trimethylene linkages between five nitroqens in a monocyclic arrangement. A new linear homologue of tetraethylene pentamine with trimethylene linkages between nitrogens is also reported. The copper(II) and nickel(II) complexes of these amines have been prepared; the conductivity and spectral properties have been determined in order to investigate their stereochemistry. The nickel(II) complexes of the two largest macrocycles appear to be five-coordinate both in the solid state and in solution. The remainder of the complexes are either five-coordinate (as the perchlorate salts in the solid state or in non-coordinating solvents) or six-coordinate (with a coordinated nitrate). Cobalt(III) complexes of the fifteen to eighteen membered macrocycles have been prepared with a variety of ligands occupying the sixth coordination site. Ligand field parameters have been derived from the electronic spectra of the complexes. The stereochemistry of the complexes and their behaviour on ligand substitution have been investigated principally by 13C n.m.r. Only a few of the numerous possible isomers of each species were formed. The structures of [Co(1, 4, 7, 10, 14-pentaazacycloheptadecane) Cl]Br0.33 Cl1.67. H2O and [Co(1, 4, 7, 11, 15-pentaazacyclooctadecane)Br]Br2, which were determined by single-crystal x-ray diffraction studies, are described. The spontaneous aquation rates of the bromo complexes have been investigated semi-quantitatively, and found to span many orders of magnitude. The most labile bromo complex [Co(1, 4, 8, 11, 15-pentaazacyclooctadecane)Br]Br2 spontaneously aquates in a matter of seconds at room temperature. The increasing strain and steric crowding caused by successive replacement of five-membered chelate rings by six-membered chelate rings, or by simply altering the sequence of five- and six-membered chelate rings is manifested in a progressive increase in the instability of the complexes. In the case of the nineteen- and twenty-membered macrocycles, this crowding and strain results in the formation of stable five-coordinate cobalt(II) complexes; for these ligands, no stable complexes were formed with the smaller cobalt(III) cation. The acid-dissociation kinetics of the copper(II) complexes have been examined in nitric acid at 298 K. A variable temperature study has also been performed on the complex of l, 4, 7, 10, 14-pentaazacycloheptadecane in order to determine the activation parameters. The complexes are labile by comparison with most tetraazamacrocyclic complexes. The dissociation reactions are first-order in complex concentration, but the acid-dependence varies. The observed rate constant is second-order in hydrogen ion concentration for the complex of 1, 4, 7, 10, 13-pentaazacyclopentadecane, first-order in hydrogen ion concentration for 1, 4, 7, 10, 14-pentaazacycloheptadecane and takes the form kobs = a[H+]2/(l+b[H+]2) for the complex of 1, 4, 7, 10, 13-pentaazacyclohexadecane. For the remainder of the complexes, the observed rate constant takes the form kobs = (c[H+] + d[H+]2)/(e + [H+]). Possible mechanisms that are consistent with the above behaviour are presented.</p>

INFLUENCE OF pH AND TEMPERATURE ON MYOSIN INACTIVATION

1961 ◽  
Vol 39 (2) ◽  
pp. 265-272 ◽  
Author(s):  
Gérard E. Pelletier ◽  
Ludovic Ouellet
Keyword(s):  
Structural Changes ◽  
Electrostatic Charge ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Kcal Mole ◽  
Order Process ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Inactivation Process ◽  
Influence Of Ph

The inactivation of myosin adenosine triphosphatase activity was studied in 0.6 M potassium chloride solution at pH ranging from 7.0 to 10.8 and for 5 °C to 40 °C. The inactivation is a first-order process with respect to time and 0.6th order with respect to the concentration of protein. The rate of inactivation is independent of the pH for pH 7.0 to pH 8.5 at 35 °C and increases rapidly with pH at higher pH. At 12 °C, close to pH 10.4, the rate is inversely proportional to the 4.5th power of the hydrogen ion concentration. The energies of activation are 56 kcal mole−1 at pH 8.0 and 58 kcal mole−1 at pH 10.5. A discussion of the data stresses the importance of structural changes and indicates a possible role for the electrostatic charge in the inactivation process.

The Formation of 3-Phenyl-2-thiohydantoins from Phenylthiocarbamyl Amino Acids

1963 ◽  
Vol 16 (3) ◽  
pp. 411 ◽  
Author(s):  
D Ilse ◽  
P Edman
Keyword(s):  
Amino Acids ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ions ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Degradation Of Peptides

In an attempt to extend the application of the phenylisothiocyanate degradation of peptides it was found necessary to study the kinetics of the conversion of phenylthiocarbamyl amino acids into phenylthiohydantoins. The conversion was found to obey first-order kinetics and to be catalyzed by hydrogen ions. A set of conditions with regard to time, hydrogen ion concentration and temperature was found, which allowed the quantitative or near quantitative conversion of all phenylthiocarbamyl amino acids into phenylthiohydantoins with the only exception of the phenylthiohydantoin of serine, which was returned in a yield of 20%.

scholarly journals An Investigation of Some Aspects of the Coordination Chemistry of Synthetic Macroheterocyclic Ligands

2021 ◽  
Author(s):  
◽  
Peter Osvath
Keyword(s):  
Solid State ◽  
Rate Constant ◽  
Variable Temperature ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Dissociation ◽  
Ligand Field ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Chelate Rings

<p>The preparation of a range of fully saturated, unsubstituted pentaazamacrocycles is described. The macrocycles vary in ring size from fifteen to twenty members, and comprise every possible arrangement of dimethylene and trimethylene linkages between five nitroqens in a monocyclic arrangement. A new linear homologue of tetraethylene pentamine with trimethylene linkages between nitrogens is also reported. The copper(II) and nickel(II) complexes of these amines have been prepared; the conductivity and spectral properties have been determined in order to investigate their stereochemistry. The nickel(II) complexes of the two largest macrocycles appear to be five-coordinate both in the solid state and in solution. The remainder of the complexes are either five-coordinate (as the perchlorate salts in the solid state or in non-coordinating solvents) or six-coordinate (with a coordinated nitrate). Cobalt(III) complexes of the fifteen to eighteen membered macrocycles have been prepared with a variety of ligands occupying the sixth coordination site. Ligand field parameters have been derived from the electronic spectra of the complexes. The stereochemistry of the complexes and their behaviour on ligand substitution have been investigated principally by 13C n.m.r. Only a few of the numerous possible isomers of each species were formed. The structures of [Co(1, 4, 7, 10, 14-pentaazacycloheptadecane) Cl]Br0.33 Cl1.67. H2O and [Co(1, 4, 7, 11, 15-pentaazacyclooctadecane)Br]Br2, which were determined by single-crystal x-ray diffraction studies, are described. The spontaneous aquation rates of the bromo complexes have been investigated semi-quantitatively, and found to span many orders of magnitude. The most labile bromo complex [Co(1, 4, 8, 11, 15-pentaazacyclooctadecane)Br]Br2 spontaneously aquates in a matter of seconds at room temperature. The increasing strain and steric crowding caused by successive replacement of five-membered chelate rings by six-membered chelate rings, or by simply altering the sequence of five- and six-membered chelate rings is manifested in a progressive increase in the instability of the complexes. In the case of the nineteen- and twenty-membered macrocycles, this crowding and strain results in the formation of stable five-coordinate cobalt(II) complexes; for these ligands, no stable complexes were formed with the smaller cobalt(III) cation. The acid-dissociation kinetics of the copper(II) complexes have been examined in nitric acid at 298 K. A variable temperature study has also been performed on the complex of l, 4, 7, 10, 14-pentaazacycloheptadecane in order to determine the activation parameters. The complexes are labile by comparison with most tetraazamacrocyclic complexes. The dissociation reactions are first-order in complex concentration, but the acid-dependence varies. The observed rate constant is second-order in hydrogen ion concentration for the complex of 1, 4, 7, 10, 13-pentaazacyclopentadecane, first-order in hydrogen ion concentration for 1, 4, 7, 10, 14-pentaazacycloheptadecane and takes the form kobs = a[H+]2/(l+b[H+]2) for the complex of 1, 4, 7, 10, 13-pentaazacyclohexadecane. For the remainder of the complexes, the observed rate constant takes the form kobs = (c[H+] + d[H+]2)/(e + [H+]). Possible mechanisms that are consistent with the above behaviour are presented.</p>

The Relation between the Rate of Production of Gastric Juice and its Electrolyte Concentrations

1970 ◽  
Vol 39 (1) ◽  
pp. 61-75 ◽  
Author(s):  
M. Hobsley ◽  
W. Silen
Keyword(s):  
Linear Relationship ◽  
Gastric Juice ◽  
Chloride Ion ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Acid Component ◽  
Volume Rate ◽  
Fixed Composition ◽  
Analytical Errors

1. Repeated 15-min collections of gastric juice were made during the plateau of response to an intravenous infusion of histamine diphosphate 0·01 mg h−1 kg−1 and the samples measured and their electrolyte concentrations estimated. A linear relationship was found between chloride output and the volume-rate of overall secretion and between hydrogen ion output and the same rate of secretion, while a multivariate linear relationship was also found between all three variables. 2. A mathematical analysis of these results suggests that if gastric secretion consists of an acid and a non-acid component, each of fixed composition, then the acid component has the composition H = 143 mEq/l, K = 16 mEq/l, Cl = 169 mEq/l, and the non-acid component is secreted at the same rate in different subjects under these circumstances. 3. The data enable gross sampling and analytical errors to be detected; in particular, the volume-rate of secretion can be predicted from hydrogen ion concentration, better from chloride ion concentration, and best from the concentrations of both ions. 4. For single samples such predictions appear to be superior to the direct measurement of volume.

Kinetics of the oxidation of Pu(IV) by manganese dioxide

2002 ◽  
Vol 90 (2) ◽  
Author(s):  
A. Morgenstern ◽  
Gregory R. Choppin
Keyword(s):  
Manganese Dioxide ◽  
Rate Equation ◽  
Oxidation Reaction ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Order Dependence ◽  
Ph Range ◽  
Kinetics Of

SummaryThe kinetics of the oxidation of plutonium(IV) by manganese dioxide were studied in 1.0 M NaCl over the pH range from 2.5 to 8.2 with variable concentrations of manganese dioxide from 0.01 mIn the pH range from 2.0 to 3.5, the oxidation of Pu(IV) by manganese dioxide was first order with respect to the concentration of manganese dioxide and −0.21 with respect to the hydrogen ion concentration. Consequently, assuming a first order dependence with respect to the concentration of Pu(IV), the oxidation reaction can be described by the following rate equation:with

scholarly journals ANOMALIES IN THE ABSORPTION SPECTRUM AND BLEACHING KINETICS OF VISUAL PURPLE

1936 ◽  
Vol 19 (4) ◽  
pp. 577-599 ◽  
Author(s):  
Aurin M. Chase
Keyword(s):  
Seasonal Variation ◽  
Order Equation ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Seasonal Effect ◽  
Hydrogen Ion Concentration ◽  
Winter Condition ◽  
First Order ◽  
Summer Condition ◽  
Kinetics Of

Visual purple from winter frogs shows an intermediate yellow color during bleaching by light; summer extractions do not. This seasonal effect can be duplicated by variations in the hydrogen ion concentration and in the temperature of the solutions. Increasing the pH approximates the summer condition, while decreasing the pH approximates the winter condition. Temperature has no effect on the bleaching of alkaline solutions but greatly influences acid solutions. At low temperatures the bleaching of add solutions resembles the winter condition, while at higher temperatures it resembles the summer condition. A photic decomposition product of frog retinal extractions is an acid-base indicator: it is yellow in acid and colorless in alkaline solution. Its color is not dependent upon light. The hydrogen ion concentration of visual purple solutions does not change under illumination, nor is there a difference in the pH of summer and winter extractions. Bile salt extractions of visual purple are usually slightly acid. The conflicting results of past workers regarding the appearance of "visual yellow" may be due to seasonal variation with its differences in temperature, or to the presence of base in the extractions. It is also possible that vitamin A may be a factor in the seasonal variation. The photic decomposition of visual purple in bile salts solution, extracted from summer frogs, follows the kinetics of a first order reaction. Visual purple from winter frogs does not conform to first order kinetics. Photic decomposition of alkaline, winter visual purple extractions also follows a first order equation. Acid, winter extractions appear to conform to a second order equation, but this is probably an artefact due to interference by the intermediate yellow.

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