Cyanide Ion Concentration Research Articles

Kinetics of autoreduction of iron(III) porphyrins by cyanide ion

The autoreduction of ferric porphyrins in the presence of cyanide ions in dimethyl sulfoxide (DMSO) is followed by visible spectroscopy. The presence of an isosbestic point during autoreduction from iron(III) to iron(II) porphyrins suggests it to be an equilibrium process. The observed rate of reduction was found to be linearly dependent on the concentration of cyanide ion. The rate constants calculated for three iron porphyrins viz. tetraphenyl- porphyrin iron(III), deuteroporphyrin dimethyl ester iron(III) and octaethyl porphyrin iron(III) are 240, 165 and 120 M −1 s −1, respectively. The rate constants are found to increase with a decrease in the basicity of the porphyrin. Based on these observations, a nucleophilic attack mechanism is proposed which explains the linear dependence of the observed rate.

In Vitro Cyanide Release from Sodium Nitroprusside in Various Intravenous Solutions

The concentration of cyanide, a toxic metabolite of sodium nitroprusside, in solutions other than 5% dextrose in water, has not been reported. In this study, cyanide ion levels were measured by a cyanide ion-specific electrode in 250 ml of six different intravenous solutions (5% dextrose in water, 10% dextrose in water, distilled water, 0.9% sodium chloride, and lactated Ringer's solution with and without 5% dextrose) exposed to 300 foot candles of fluorescent light for 72 hours after sodium nitroprusside was dissolved in each solution. The rates of the increase in cyanide ion concentration in all six solutions were fairly constant between 4 and 24 hours. At 24 hours, there were no statistically significant differences in cyanide ion concentration among the six solutions. After 24 hours, the rate of the increase in cyanide ion concentration in the electrolyte solutions decreased more than that in the nonelectrolyte solutions. At 72 hours, the electrolyte-containing solutions had statistically significant lower mean cyanide ion concentrations than 5% dextrose, often the recommended diluent for sodium nitroprusside. There was no difference in mean cyanide ion concentration between lactated Ringer's solution with and without 5% dextrose. Solutions containing electrolytes are preferable to 5% dextrose for the dilution of sodium nitroprusside.

Kinetics of the reversible photoaquation of the octacyanomolybdate(IV) ion

The kinetics of the photoaquation of the octacyanomolybdate(IV) ion in aqueous solution were studied by potentiometric and spectrophotometric methods. In an alkaline medium a simple scheme analogous to the photoaquation of the hexacyanoferrate(II) ion describes the process. The values of the constants of the kinetic equation are: (Φ = 1.0, k 8 = (6.55 ± 0.8) x 10 −9 s −1, and k −8 = (7.88 ± 0.5) x 10 −2 mol −1 dm 3 s −1 (pH = 10.5). The reversibility of the photoaquation is also explained by the scheme. A simultaneous measurement of free cyanide ion concentration and the absorbance at 512nm shows that the red coloured transition product is a heptacyano complex.

Kinetics and mechanism of ligand substitution reactions of NiL and Ni2L with cyanide ion (L = hexamethylenediaminetetraacetic acid)

The kinetics and mechanism of reactions of cyanide ion with [NiL] and [Ni2L] (L = hexamethylenediaminetetraacetic acid) have been studied spectrophotometrically at 25 ±0.1 °C, with pH=11.0±0.02, and I=0.1 M(NaClO4). In both reactions the final product was [Ni(CN)4]2−. The order with respect to [CN−] was found to be one over a wide range of cyanide ion concentrations for both the systems.

An electrochemical and Raman spectroscopic investigation of synergetic effects in the corrosion inhibition of copper

The synergetic inhibition of copper corrosion by benzotriazole (BTA) and benzylamine (BZA) in chloride and cyanide media is assessed by voltammetric and ac impedance measurements. BZA enhances the performance of the strong inhibitor BTA by accelerating the growth of a protective surface layer; used alone, BZA is ineffective as an inhibitor. The competitive adsorption of aggressive anions and inhibitors is studied by surface enhanced Raman scattering (SERS). The dramatic increase in corrosion caused by low concentrations of cyanide ions is shown to be due to the displacement of BTA from the copper electrode surface; comparisons are made with the behaviour of mercaptobenzoxazole (MBO).

Interaction of lead ions with bovine carbonic anhydrase: further studies

Lead-substituted bovine carbonic anhydrase is investigated and the return to the holoenzyme form with exchange of Pb 2+ by Zn 2+ is followed by uv difference spectroscopy and by esterase activity methods. Equimolar amounts of Pb 2+ added to apocarbonic anhydrase release one hydronium ion per molecule below pH 6. Above this pH there is a net gain of hydronium ions by the enzyme, due to Pb(OH) + → Pb(OH 2) 2 +, when the metal is bound within the active site of the enzyme molecule. The reduced hydrolysis by lead when it is bound to the enzyme is relevant to the theory of Zn 2+ hydrolysis as a mechanism for carbon dioxide hydration by the holoenzyme and to the idea of an altered p K hydrolysis when Zn 2+ is bound in the enzyme active site cavity. Lead appears to be bound to a His residue in the active site and to interact with a Tyr residue nearby. The Tyr interaction is disrupted by a high concentration of chloride ions, (also by lower concentrations of cyanide ions), but such anions do not displace lead from the enzyme. At pH 8.0 the buffer-free exchange of Pb 2+ by Zn 2+ is found to be consistent with a second-order process with an effective β = (95 ± 7) M −1 sec −1. Thus lead is more rapidly replaced by zinc than is Mn 2+ or VO 2+ whose replacement kinetics have been reported by others. Comparison of esterase-activation and spectral curves with second-order models shows that the effective β is both large and buffer dependent, indicating that a proton transfer process or buffer anion effects may be rate limiting in the buffer-free case.

Use of a Silver Ion Selective Electrode for the Determination of Stability Constants of Metal Complexes

The potential response of a sulfide-based silver ion selective electrode was examined in various metal buffer solutions. In every system tested, the potential response of the electrode was rapid and the electrode potential correctly reflected the free silver ion concentration in the solution. The stability constants of silver complexes with seven ligands were determined. This electrode was used also to measure the free cyanide ion concentration in the solutions containing silver, cyanide and a second metal ion. The stability constants of zinc and cadmium cyano complexes were obtained. The behavior of the silver ion selective electrode is discussed in contrast to that of the mixed sulfide membrane electrodes.

The chemistry of uranium. Part XXVI. Alkaline dissolution of gold and/or uranium dioxide powders

The simultaneous dissolution of gold and uranium dioxide in solutions containing sodium carbonate, sodium bicarbonate and potassium cyanide has been studied. The effect of the presence of 0.025% potassium cyanide on the dissolution rate of uranium dioxide alone has been studied at different temperatures. The effect of 4% sodium carbonate and 1.5% sodium bicarbonate on the dissolution rate of gold has similarly been investigated. The presence of potassium cyanide proved to have little effect on the dissolution rate of uranium dioxide within the temperature range 30°–80°C. The decrease in the rate of dissolution of gold, in the presence of sodium carbonate and sodium bicarbonate, is attributed to the lower pH (10.2) and resulting lower cyanide ion concentration of the system, compared to that of the industrial cyanide solution (11.8). Whereas the dissolution rate of uranium dioxide is temperature dependent that of gold is approximately temperature independent in the range 60–80°C. It was found that 85% of the uranium dioxide and 95% of the gold could be dissolved in a simultaneous leach.

Spectrophotometric determination of cyanide ions through ligand exchange reaction in solution

A simple spectrophotometric method for the determination of trace amounts of cyanide ions in aqueous medium, using a heterocyclic azo dye complexed with mercury(II) for the first time, is described. The visual comparative method has been used in which a stronger complexing anion displaces a coloured reagent from the metal-ligand complex. Ammonium (2′-amino-3′-hydroxy-pyridyl-4′ azo)benzene-4-arsonate (AHP-4A) complexed with mercury(II) has been used for the determination of 0.13–1.46μg/ml of cyanide ions with fair accuracy. The anion has also been determined, when cyanide ion reacts with mercury(II)-(AHP-4A) complex, probably forming a bridged complex. The increase in absorbance is proportional to the cyanide ion concentration in the range of 0.04–0.37μg/ml, but this method is not very precise. The effect of foreign ions has also been studied. The sensitivities of other mercury(II) complexes in the determination of cyanide ions have been compared.

Synthetic applications of N–N linked heterocycles. Part 4. The reaction between 1-pyridinio-4-pyridone cations and cyanide ion: mechanism of cyanopyridine formation, and a regioselective synthesis of 4-cyanopyridines

The 1-pyridinio-4-pyridone cations (1) give with aqueous sodium cyanide mixtures of 2- and 4-cyanopyrigines, 2-cyanopyridine formation being favoured by high cyanide ion concentration, and 4-cyanopyridine formation by low cyanide ion concentration, when small amounts of the intermediate 1,4-dihydro-4-cyano-adducts (7) or (9) are also observed. The 2,6-dimethyl-1-pyridinio-4-pyridone cations (2) in contrast give high yields of the 1,4-dihydro-4-cyano-adducts (8) or (10), the former being decomposed quantitatively by heat to 4-cyanopyridines and 2,6-dimethyl-4-pyridone. Only very small amounts of 2-cyanopyridines are formed. Mechanisms for the two reactions are proposed which account for the experimental observations.

The kinetics of the dissolution of chalcocite in alkaline cyanide solution

A kinetic study of the dissolution of chalcocite in an alkaline cyanide solution indicates that the reaction is first order with respect to surface area and free cyanide ion concentration, and inversely proportional to the sulfide ion concentration to approximately the 0.1 power. The experimental rate constant is approximately 7.5 × 10−5 (mole Cu1+/ min) ([S−2]0.1/[CN1−]/cm2/l at 25°C. The activation energy of 2.5 kcal/mole indicates rate control by diffusion through a limiting boundary layer. The concentrations of the important ions in the cyanide solutions are obtained by solving the ionic equilibria and mass balance equations for the system.

An improved ion exchange resin method for removal and recovery of zinc cyanide and cyanide from electroplating wastes

Abstract The removal, concentration, and recovery of zinc cyanide and cyanide ion from industrial electroplating wastes can be readily achieved with the weakly basic anion exchange resin, Amberlite XE‐275. Dilute sodium hydroxide easily strips both the metal cyanide and cyanide in a regeneration cycle. This new nondestructive process is promising for the recovery and recycle of water and costly chemicals now wasted and for the elimination of sludge disposal problems associated with current destructive pollution abatement methods.

Reactions of the bis(ethylenediamine)-(pyrazinecarboxylate)cobalt(III) complex with the aquopentacyanoferrate(III) and pentacyanocobaltate(II) ions

The reactions of the complex bis(ethylenediamine)-(pyrazinecarboxylate)cobalt(III) perchlorate with the complex ions aquopentacyanoferrate(II) and pentacyanocobaltate(II) are described. An inner sphere mechanism was postulated for the electron transfer reaction with the pentacyanocobaltate(II) ion, based on the analysis of the products and on the independence of the rates with respect to the cyanide ion concentration. The specific rate, ΔH ‡, and ΔS ‡ at 25°C and μ = 0·10 M LiClO 4, were 3·1 × 10 7 M −1 s −1, 5 kcal/mole and −7 e.u., respectively. The reaction of the cobalt(III)-pyrazinecarboxylate complex with the aquopentacyanoferrate(II) ion yielded a very stable binuclear complex, of an association constant equal to 8·3 × 10 6 M −1 at 25°C and μ = 0·20 M, LiClO 4. The reaction of the bis(ethylenediamine)(pyridine-carboxylate)cobalt(III) complex with the pentacyanocobaltate(II) ion, studied under similar conditions, was found to occur by competitive inner sphere and outer sphere mechanisms. The specific rates for the inner and outer sphere pathways were equal to 1·6 × 10 3 M −1 s −1 and 8·3 × 10 4 M −2 s −1, respectively (25°C, μ = 0·10 M LiClO 4).

Kinetics and mechanism of replacement of nitrosobenzene in the pentacyano(nitrosobenzene)ferrate(II) ion by cyanide ion

The rate of replacement of nitrosobenzene by cyanide ion in the complex [Fe(CN)5(PhNO)]3– increases non-linearly with the cyanide-ion concentration, reaching an asymptotic value at [CN–]ca. 2 × 10–3M in 1·5 × 10–4M complex solution. A limiting SN1 mechanism is proposed.

KINETICS OF THE REACTION BETWEEN CYANIDE AND N,N′-ETHYLENEDIAMINEDISUCCINATONICKEL(II)

Abstract Fourth order kinetics are observed in rate of formation of Ni(CN)4 2- from N,N′-ethylenediaminedisuccinatonickel (II), (NiEDDS2-). The reaction is first order in NiEDDS2- and third order in total cyanide (CN− + HCN) over a -log[H+] range of 7.5 to 11.0 The rate of formation of Ni(CN)4 2- is equal to (K 1 K 2 k 3,0[CN−]3 + K 1 K 2 k 2,1[CN−]2[HCN])[NiEDDS2-] where K 1 K 2 k 3,0=2.0 × 107 M −3 sec−1 and K 1 K 2 k 2,1=1.1 × 107 M −3 sec−1. The reverse reaction is first order in Ni(CN)4 2-, first order in EDDS and inverse order in cyanide ion concentration, confirming the forward kinetics. The kinetic results indicate that all six donor sites of EDDS are coordinated to the nickel atom.

Fluid transport in the rabbit blastocyst.

Osmolaritätsmessungen zeigen, daß während früher Schwangerschaftsstadien die Blastocoel-Flüssigkeit isoosmotisch ist mit der uterinen Flüssigkeit, daß sie aber in vitro hypotonisch wird mit Bezug auf das Inkubationsmedium. Blastozysten können Flüssigkeit aufnehmen gegen einen erheblichen osmotischen Gradienten von Saccharose oder Mannitol. Diese Beobachtungen eliminieren die Möglichkeit, daß einfache Osmose für die Flüssigkeitsakkumulation verantwortlich ist, die während des Wachstums von Blastozysten erfolgt. Aktiver Transport wird nahegelegt durch die Tatsache, daß definierte Konzentrationen von Zyanidionen oder 2,4-Dinitrophenol die Akkumulation von Flüssigkeit verhindern.Ergebnisse von Experimenten von kultivierten Embryonen zeigen, daß optimale Natrium- und Chloridionenkonzentrationen nötig sind für die Ausdehnung des Blastozysten, während Natrium-, Calcium- und Magnesiumionen den Flüssigkeitstransport nicht direkt zu beeinflussen scheinen.Das elektrochemische Verhalten von Trophoblasten wurde durch Mikroelektroden untersucht, die in das Blastocoel eingeführt wurden. Kleine, aber dauernde elektrische Potentiale existieren; die Seite, gegen welche Flüssigkeittransport gerichtet war, wurde negativ bei etwa zwei mV. Hohe Osmolarität des Mediums bewirkte, daß das Potential um einen Faktor 3 anstieg, während Zyanidionen oder Dinitrophenol das Potential elimierten. Ein Natriummengelmedium erhielt ein Transtrophoblast-Potential vergleichbar mit einem in normalem F 10, während in einem Chloridionenmangelmedium die Potentialdifferenz verschwand. Wenn F 10 Natriumsulfat statt Natriumchlorid enthielt, zeigte der Trophoblast kein Potential; wenn aber Sodiumchlorid durch Sodiumbromid ersetzt wurde, kam es zu einer relativ hohen negativen Spannung.Diese Ergebnisse stehen im Einklang mit Beobachtungen an der Gallenblase des Kaninchens, für welche das Curran Doppelmembranmodell in Anwendung kommt. Wenn man physiologische, elektrische und strukturelle Eigenschaften betrachtet, ist dieses Modell relevant für die Flüssigkeitsaufnahme der Kaninchenblastozysten.

Chemical Behavior of the Components of the KCN / KAu ( CN ) 2 Electroplating System

The chemical reactions occurring within aqueous solutions of potassium cyanide, potassium cyanide and metallic gold, potassium gold cyanide, and mixtures of these compounds with potassium hydroxide have been examined. It was determined that aqueous potassium cyanide solutions are unstable to water and air. The major reaction products formed were the formate and carbonate ions which increased in concentration with time. This increase, which was temperature dependent, was accompanied by a corresponding decrease in the cyanide ion concentration. Analyses confirmed that gold would dissolve, to any extent, only in those aqueous potassium cyanide solutions exposed to air. The reactions of potassium cyanide with water and oxygen within solutions of potassium cyanide and metallic gold produced similar products to those found in pure potassium cyanide solutions.The addition of potassium hydroxide in concentrations greater than ∼0.1M to aqueous potassium cyanide solutions depressed the rate of hydrolysis of potassium cyanide. However, concentrations far in excess of 1M potassium hydroxide would be necessary to prevent the formation of formate ion completely. Analyses confirmed that aqueous potassium gold cyanide solutions are very stable to heat, high concentrations of hydroxide ion and atmospheric oxygen, and show no detectable signs of decomposition. The solutions are likewise stable to acid at room temperature down to a pH of ∼4.5, below which a slow decomposition to insoluble gold cyanide occurs. At pH 1, aqueous potassium gold cyanide solutions remain stable indefinitely at a temperature of 1°C. In mixtures of potassium gold cyanide, potassium cyanide, and potassium hydroxide, which are typical electroplating solution components, the stability of potassium gold cyanide was apparently unaffected. The reactions of potassium cyanide with water and oxygen within these mixtures gave no other products but those detected in a pure potassium cyanide solution. Potassium hydroxide merely decreased the rate of hydrolysis of the potassium cyanide.Activated charcoal treatment of the cyanide solutions did not remove any of the ionic products of decomposition.

Kinetics of silver cementation on zinc in alkaline cyanide and perchloric acid solutions

The rates of silver cementation were measured by chemical analysis while rotating zinc cylinders in deoxygenated silver (I) solutions at controlled peripheral velocities and temperatures.The rates were dependent on peripheral velocity in both alkaline cyanide and perchloric acid solutions. They were more rapid in the acid media. In both media the cementation rates obeyed a pseudo-first-order rate law at the beginning of the experiments when the deposited silver did not influence the reaction.In alkaline cyanide solutions the deposits were dense and adherent platings, but in perchloric acid solutions they were loose and finely divided powders. In the cyanide media the deposits had little or no influence on the rate constant k, except at very low free cyanide ion concentrations, when k markedly decreased after a certain amount of reaction. In perchloric acid solutions, the rate constant, which was constant initially, increased with increasing deposition. This increase was caused by the formation of powder deposits.Activation energies, calculated for the temperature range of 5°C to 55°C, were 5 to 6 kcal/mole for both alkaline and acidic solutions. Résumé Les taux de cémentation d'argent ont été mesurés par analyse chimique sur des cylindres de zinc toumant dans des solutions (I) désoxygénées d'argent, tout en assurant régulation de la vitesse tangentielle et de la température.Les taux dépendaient de la vitesse tangentielle tant dans les solutions de cyanures alcalines que dans les solutions d'acide perchlorique. Ils étaient plus élevés en milieu acide. Dans chaque milieu les taux de cémentation obéissaient à une loi de pseudopremier ordre au débu t des essais alors que l'argent déposé n'influenčait pas la réaction.Dans les solutions de cyanures alcalines les dépôts étaient des plaqués denses et adhérents mais dans les solutions d'acide perchlorique les dépôts étaient des grains fins de poudre, non adhérents. Dans le milieu de cyanures, les dépôts avaient peu ou pas d'influence sur la constante de vitesse k, sauf pour des trés faibles concentrations d'ions libres de cyanures, alors que k décroissait de fačon marquée après un certain temps de réaction. Dans les solutions d'acide perchlorique, la vitesse spécifique qui était constante initiallement, croissait avec une déposition accrue. Cette augmentation était due à la formation de dépôts non recouvrants.Les valeurs d' énergie d'activation, calculées sur l'intervalle de 5 à 55°C, étaient de 5 à 6 kcal/mole, pour les solutions alcalines et acides.

Hygienic Chemistry of Cyanide in Waste Water

It has been discussed and proposed by the Central Pharmaceutical Affairs Council of Japan that the maximum allowable concentration of cyanide ion (CN-) in plating waste water should be under 2 ppm. The standard value of 2 ppm is not applied to such complex cyanides as ferrocyanide and ferricyanide, but to the free cyanide which is liberated by aeration through the test solution at pH 5.0 and 50∼55°C, because the toxicity of the complex cyanide is less than onethousandth of that of the free cyanide. The determination procedure of free cyanide ion listed in Japanese Industrial Standard (JISK0102-1964) was modified to improve in several points, for example, pH control of the test solution and the adoption of ball filter in aeration apparatus and 1N NaOH solution as absorbing solution for HCN. The methods for removal of HCN, such as alkali-chlorine method and Fe-complex method, were reviewed shortly.

Studies on the mechanism of inhibition of monoamine-oxidase by hydrazine derivatives

A comparative study has been made of the inhibition of monoamineoxidase by hydrazine derivatives and of their cupric-ion catalysed decomposition. Both processes require oxygen and both are potentiated by low concentrations of cyanide ions. Several compounds which chelate with cupric ions suppress the catalysed decomposition of hydrazines and reduce the extent of inhibition of monoamine-oxidase produced by 2-phenylisopropylhydrazine or iproniazid. Hydroquinone and 1,2-naphthaquinone-4-sulphonic acid also protect monoamine-oxidase from inhibition by iproniazid but accelerate its cupric-ion catalysed decomposition. Some of these chelating agents and related compounds themselves inhibit monoamine-oxidase. 8-Hydroxyquinoline behaves as a typical competitive inhibitor but inhibition by hydroquinone is largely non-competitive. Inhibition of monoamine-oxidase by hydrazines may also be prevented by 2-phenylisopropylamine, a reversible, competitive monoamine-oxidase inhibitor, which does not affect the catalysed decomposition of hydrazines. The inhibitory activity of 2-phenylisopropylhydrazine is considerably reduced by N-methylation and almost abolished by N′-methylation. N-Alkylation of benzylhydrazine also reduces its inhibitory action. In contrast, N-methylation, N-ethylation or N, N-dimethylation of 2-phenylisopropylamine do not appreciably diminish its monoamine-oxidase inhibitory properties. p-Tolylhydrazine, tert.-butylhydrazine and N-benzylhydroxylamine are irreversible inhibitors of monoamine-oxidase, similar in their kinetic behaviour to arylalkylhydrazines, but less potent. The suggestion that monoamine-oxidase is a copper enzyme in which the copper catalyses the decomposition of hydrazine derivatives in a similar manner to free cupric ions, would explain many of these characteristic features of monoamine-oxidase inhibition.