THE MECHANISMS OF PERMANGANATE OXIDATION VI. THE OXIDATION OF CYANIDE ION

1960 ◽  
Vol 38 (11) ◽  
pp. 2237-2255 ◽  
Author(s):  
Ross Stewart ◽  
R. Van der Linden
Keyword(s):  
Salt Effect ◽  
Ion Concentration ◽  
Cyanide Ion ◽  
Barium Ions ◽  
Ion Concentrations ◽  
Permanganate Oxidation ◽  
Parallel Processes ◽  
Hydroxyl Ion ◽  
Kinetic Expression ◽  
Tracer Experiments

Kinetic and oxygen-18 tracer experiments have been used in an attempt to elucidate the mechanism(s) of permanganate oxidation of cyanide. From pH 12 to 14.6 the oxidation is represented by the equation,[Formula: see text]From pH 12 to 6 the reaction was found to be complex and unstoichiometric yielding cyanate, carbon dioxide, cyanide ion, and finally cyanogen at pH 9 to 6.The rate of reduction of permanganate, as followed iodometrically and spectrophotometrically, is found to be markedly dependent on the pH of the medium and reactant concentration. The rate is negligible in acid solution but rapid in basic media.At pH greater than 12 two parallel processes are indicated which have been designated as reaction A and reaction B. Reaction A appears at low reactant concentrations 0.0004 M cyanide and higher hydroxyl ion concentrations pH 13 and is represented by the kinetic expression[Formula: see text]where k2 is independent of hydroxyl ion concentration and is insensitive to the presence of manganate and barium ions. A positive salt effect is observed and labeling experiments using permanganate enriched in oxygen18 showed that the oxygen introduced into the product cyanate comes mainly from the oxidant (70%–80% oxygen-18 transferred).The existence of a second process reaction B was indicated by the changing kinetics at higher reactant concentrations and lower basicities, by the non-linear Arrhenius plots, and by the observation that only 15–25% oxygen-18 transfer from permanganate to substrate had occurred at pH 13. The rate of this latter process is approximately represented by the kinetic expression[Formula: see text]These reactions are discussed in terms of mechanism

A Pretreatment Method for Detection of Cyanide Ion Concentration in Decontamination Wastewater

2013 ◽  
Vol 864-867 ◽  
pp. 101-105
Author(s):  
Ya Wei Cai ◽  
Lian Yuan Wang ◽  
Hai Yan Zhu ◽  
Meng Meng Ma ◽  
Hong Peng Zhang ◽  
...  
Keyword(s):  
Ion Concentration ◽  
Cyanide Ion ◽  
Indicator Method ◽  
Pretreatment Method ◽  
Standing Time ◽  
Ion Concentrations ◽  
Detection Process ◽  
Iodide Solution

Three oxidant decontaminants, including NaClO, H2O2 and an organic peroxyl acid, were introduced to destroy the cyanide ion. The residual cyanide ion concentrations in different decontamination water were detected by a cyanide ion selective meter. Before the detection process, the oxidants left in the cyanide decontamination water were pretreated by adding a certain amount of Na2SO3. Results showed that starch-iodide solution indicator method presented a perfect function on determining the dosage of Na2SO3. Values of the relative mean deviations on residual cyanide detection were below 5%. After the decontamination water was deoxidized by Na2SO3, whether the sample distillated or not could not affect the value of CN- quite much. Non-distillation was confirmed alternative in the detection of cyanide ion decontamination water. Too much standing time would lead to a relatively lower CN- concentration, especially in that of non-distillation.

The reaction of N-t-Butyl-2,4,6-trinitrobenzamide with sodium hydroxide. A unimolecular nucleophilic aromatic substitution

1965 ◽  
Vol 18 (5) ◽  
pp. 699 ◽  
Author(s):  
PJ Hutchison ◽  
RJL Martin
Keyword(s):  
Nucleophilic Substitution ◽  
Equilibrium Constant ◽  
Kinetic Data ◽  
Zero Order ◽  
Ion Concentration ◽  
Nucleophilic Aromatic Substitution ◽  
Anionic Complex ◽  
Aromatic Substitution ◽  
Ion Concentrations ◽  
Hydroxyl Ion

N-t-Butyl-2,4,6-trinitrobenzamide undergoes a nucleophilic substitution with hydroxyl ions to form nitrite ions. The amide is stable during this reaction and will only undergo hydrolysis under the more drastic conditions of higher hydroxyl ion concentrations at higher temperatures. The observed rate of the nucleophilic substitution is inversely proportional to the hydroxyl ion concentration. In the presence of alkali, the amide is in equilibrium with a red anionic complex and the equilibrium constant has been calculated from the kinetic data. When allowance has been made for this equilibrium, it is found that the formation of nitrite ions from the amide is zero order with respect to the hydroxyl ion concentration.

Properties of an electroless copper process as a function of nickel and cyanide ion concentrations

2021 ◽  
Author(s):  
Delilah A. Brown ◽  
Alex R. MacDonald ◽  
Eamon A. McCarron ◽  
Sebastian Zarwell ◽  
Tobias Bernhard ◽  
...  
Keyword(s):  
Cyanide Ion ◽  
Ion Concentrations ◽  
Electroless Copper

Thermal stability of ribosomes from a thermophilic and a mesophilic fungus

1973 ◽  
Vol 19 (6) ◽  
pp. 761-763 ◽  
Author(s):  
H. M. Miller ◽  
M. G. Shepherd
Keyword(s):  
Thermal Stability ◽  
Ion Concentration ◽  
Magnesium Ion ◽  
Penicillium Notatum ◽  
Ribosomal Subunits ◽  
Ion Concentrations ◽  
Thermal Stability Of

Ribosomes and ribosomal subunits from the thermophile Penicillium duponti were found to be more thermostable than the corresponding particles from the mesophile Penicillium notatum. The thermostability of the ribosomes from both organisms was dependent on magnesium ion concentration. The dissociation of the 80-S ribosomes into 60-S and 40-S subunits occurred at higher magnesium ion concentrations for the mesophile than the thermophile.

scholarly journals From ionising radiation to air ion formation in the lower atmosphere

2016 ◽  
Author(s):  
Xuemeng Chen ◽  
Veli-Matti Kerminen ◽  
Jussi Paatero ◽  
Pauli Paasonen ◽  
Hanna E. Manninen ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Ionising Radiation ◽  
Ion Concentration ◽  
Lower Atmosphere ◽  
Forest Site ◽  
Long Distance ◽  
Ion Concentrations ◽  
Ion Formation ◽  
Depth Analysis ◽  
Ion Production

Abstract. Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes, such as clustering or attachment to pre-existing aerosol particles. This study aimed 1) to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, 2) to reveal the linkage between them, and 3) to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003–2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8–1.7 nm in mobility diameters). Clear promotion effects of the ionising radiation on air ion production were demonstrated. Typically, features observed in the 0.8–1 nm ion concentration were in connection to variations of the ionising capacity. Further by carefully constraining perturbing variables, a clear relationship was also identifiable between the cluster ion concentration and the ionising capacity, proving the functionality of ionising radiation in air ion production in the lower atmosphere.

Zeolite Syntheses from Superalkaline Reaction Mixtures

1992 ◽  
Vol 57 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Falk Fischer ◽  
Marianne Hadan ◽  
Günter Fiedrich
Keyword(s):  
Ir Spectroscopy ◽  
Crystalline Phase ◽  
Ion Concentration ◽  
Single Crystalline ◽  
Hydroxyl Ion ◽  
Type Zeolite

The synthesis of faujasite-type zeolite from superalkaline reaction mixtures are described. The contribution shows the influence of component K2O added in the system Na2O-Al2O3-SiO2-H2O with H2O/(K2O + Na2O) = 13-15. The reaction course was investigated in the range K2O/(K2O + Na2O) from about 0.07 to 0.5. Under used conditions it is quite possible to isolate faujasite-type zeolite as a single crystalline phase. By means of IR spectroscopy, low SiO2/Al2O3 ratios from 2.0 to 2.1 in the faujasite framework have been indicated. The low SiO2/Al2O3 ratios are interpreted by a higher stability of the Si-O-Al- than the Si-O-Si- bond with increasing hydroxyl ion concentration.

scholarly journals OPTIMIZATION OF TIME REACTION AND HYDROXIDE ION CONCENTRATION ON FLAVONOID SYNTHESIS FROM BENZALDEHYDE AND ITS DERIVATIVES

2010 ◽  
Vol 5 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Sri Handayani ◽  
Sunarto, Sunarto, ◽  
Susila Kristianingrum
Keyword(s):  
Reaction Time ◽  
Optimum Concentration ◽  
Ion Concentration ◽  
Optimum Time ◽  
Hydroxide Ion ◽  
Synthesis Time ◽  
Flavonoid Synthesis ◽  
Hydroxyl Ion ◽  
Optimum Reaction ◽  
Time Of Reaction

The aim of this research is to determine the optimum time of reaction and concentration of hydroxide ion on chalcone, 4-methoxychalcone and 3,4-dimethoxychalcone synthesis. Chalcone and its derivatives were synthesized by dissolving KOH in ethanol followed by dropwise addition of acetophenone and benzaldehyde. Then, the mixture was stirred for several hours. Three benzaldehydes has been used, i.e : benzaldehyde, p-anysaldehyde and veratraldehyde. The time of reaction was varied for, 12, 18, 24, 30 and 36 hours. Furthermore, on the optimum reaction time for each benzaldehyde the hydroxyl ion concentration was varied from 5,7,9,11 and 13%(w/v). The results of this research suggested that the optimum time of chalchone synthesis was 12 hours, while, 4-methoxychalcone and 3,4-dimethoxychalcone were 30 hours. The optimum concentration of hydroxide ion of chalcone synthesis was 13% and for 4-methoxychalcone and 3,4-dimethoxychalcone were 11%. Keywords: Chalcone synthesis, time of reaction, hydroxide ion concentration.

Local mechanisms of phase-dependent postsynaptic modifications of NMDA-induced oscillations in the abducens motoneurons: a simulation study

1996 ◽  
Vol 76 (2) ◽  
pp. 1015-1024 ◽  
Author(s):  
I. L. Kopysova ◽  
S. M. Korogod ◽  
J. Durand ◽  
S. Tyc-Dumont
Keyword(s):  
Synaptic Input ◽  
Pattern Generation ◽  
Ion Concentration ◽  
Extracellular Potassium ◽  
Pump System ◽  
Voltage Gated ◽  
Ion Concentrations ◽  
Concentration Changes ◽  
Transmembrane Currents

1. In vivo experiments have shown that extracellular microelectrophoretic application of N-methyl-D-aspartate (NMDA) induced oscillatory plateau potentials with bursts of action potentials in rat abducens motoneurons. The period of these slow NMDA oscillations could be altered by single trigeminal non-NMDA excitatory input delivered at low frequency during the NMDA oscillations. 2. A resetting of the oscillations was observed depending on the phase of slow oscillatory cycle during which the trigeminal excitation occurred. 3. We investigated local mechanisms responsible for the phase-dependent modifications of NMDA oscillations, including contributions of voltage and concentration transients, in the mathematical model of the isopotential membrane compartment equipped with voltage-gated Na+, K+, and Ca2+ channels, with Ca2+-dependent K+ channels, and with ligand-gated NMDA and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor channels. The faithful model was constructed with the use of models described earlier, which were modified by increasing time constants of kinetic variables of all voltage-gated conductances and by including coupled dynamics of voltages and ion concentrations. The changes in ion concentrations were produced near the membrane by transmembrane currents and removal mechanisms (pumps, diffusion). 4. This work focuses on local arrangement of voltage- and ligand-gated conductances and on local ion concentration changes in two separate pools: the postsynaptic pool of AMPA receptors and the extrasynaptic pool. In terms of the electrotonic and diffusional length constants, these pools were electrotonically close but diffusionally remote. 5. It was found that the effect of resetting can be produced by a local interaction between plateau and spike-generating conductances and glutamate receptors. 6. In vivo phase-dependent interactions between NMDA oscillations and AMPA synaptic input were reproduced by the local model only when changes in intracellular sodium and extracellular potassium concentrations were taken into account and the mechanisms of ion removal from postsynaptic pools had slower kinetics than the fast pump system operating in the extracellular pool. 7. Postsynaptic changes in ion concentrations of Na+ and K+ in intra- and extracellular layers near the membrane shift of Nernst equilibrium potentials for these ions depending on the phase of activation of synaptic input. Thus Na+ and k+ components of all transmembrane currents involved in the pattern generation are differently affected by synaptic action during the oscillations. We conclude that slow postsynaptic changes in ion concentrations near the membrane play a key role in the resetting of the NMDA oscillations.

scholarly journals THE RELATION OF THE PNEUMOCOCCUS TO HYDROGEN ION CONCENTRATION, ACID DEATH-POINT, AND DISSOLUTION OF THE ORGANISM

1919 ◽  
Vol 30 (4) ◽  
pp. 389-399 ◽  
Author(s):  
Frederick T. Lord ◽  
Robert N. Nye
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Direct Relation ◽  
Hydrogen Ion Concentration ◽  
Ion Concentrations ◽  
Cent Glucose ◽  
Fluid Media

1. In the growth and death of the pneumococcus in fluid media containing 1 per cent glucose the production of acid is the most important bactericidal factor. 2. 1 per cent glucose bouillon cultures of the pneumococcus allowed to grow and die out usually reach a final acidity of a pH of about 5.1. 3. At a hydrogen ion concentration of about 5.1 or higher, the pneumococcus does not survive longer than a few hours. 4. In hydrogen ion concentrations of about 6.8 to 7.4 the pneumococcus may live for at least many days. 5. In the intervening hydrogen ion concentrations, between 6.8 and 5.1, the pneumococcus is usually killed with a rapidity which bears a direct relation to the hydrogen ion concentration; i.e., the greater the acidity the more rapid is the death. 6. Cloudy suspensions of washed pneumococci in hydrogen ion concentrations varying from 8.0 to 4.0 show, after incubation, dissolution of organisms in lower hydrogen ion concentrations than about 5.0. This dissolution is most marked at about 5.0 to 6.0. Some dissolution also takes place toward the more alkaline end of the scale. No dissolution occurs at the most acid end of the scale.

SECONDARY KINETIC SALT EFFECT IN THE CASE OF HYDROXYL-ION CATALYSIS

1925 ◽  
Vol 47 (10) ◽  
pp. 2523-2531 ◽  
Author(s):  
J. N. Brönsted ◽  
Cecil V. King
Keyword(s):  
Salt Effect ◽  
Hydroxyl Ion
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