Formation Of Cyanide Research Articles

Cyanide Production and Degradation during Growth of the Snow Mould Fungus

Summary: Isolate W2 of the snow mould basidiomycete produced cyanide only at the start of the stationary phase when it was grown in shake cultures on a glucose-containing synthetic medium in which growth stopped because of glucose depletion. Cyanogenesis was stimulated by inclusion of glycine in the medium, but the presence of methionine in addition to glycine caused little further cyanide formation. Addition of cyclic AMP to the medium had no effect on the time of production or the concentration of cyanide formed. Cultures that contained excess glucose at the start of the stationary phase also produced cyanide. Cultures which contained acetate as the carbon source formed cyanide during growth and in the stationary phase; cyanogenesis was again stimulated by glycine. In cultures containing glucose, [1-14C]glycine was converted to 14CO2 during both the growth and stationary phases, whereas [2-14C]glycine was the precursor of [14C]cyanide only at the start of the stationary phase: Very little of the cyanohydrins of glyoxylic acid or pyruvic acid were formed. Cyanide was converted to CO2, as the major detoxication product; there was little formation of alanine, β-cyanoalanine, glutamate. formamide, or aspartate plus asparagine.

The formation of hydrogen cyanide from histidine in the presence of amino acid oxidase and peroxidase

Conditions were sought to increase the yield of HCN from l-histidine incubated with l-amino acid oxidase ( l-amino acid:oxygen oxidoreductase (deaminating), EC 1.4.3.2) from snake venom, and horseradish peroxidase (donor:hydrogen-peroxide oxidoreductase, EC 1.11.1.7). Small amounts of histidine and high buffer concentrations favored high HCN yields, which reached a maximum of 72%. Imidazole 4-aldehyde and imidazole 4-carboxylic acid were identified among the reaction products, together with CO 2, NH 3, H 2O 2 and imidazole acetic acid. The CO 2 formed was equal to the histidine oxidized, and to the sum of NH 3 plus HCN formed. The production of HCN was associated with an increased O 2 uptake, which was established from the beginning of the reaction, with no apparent lag and ranged from 1.2 to 1.6 μmol extra O 2 taken up/μmol HCN formed. The system was inhibited by catalase, but added superoxide dismutase caused a small stimulation of both HCN production and O 2 consumption, and a larger stimulation of H 2O 2 accumulation. Added hydroxylamine was cooxidized to nitrite in an amount equimolar with the HCN formed. This nitrite formation was inhibited by superoxide dismutase. The facts could be interpreted in terms of superoxide anion formation during the HCN-producing reaction.

Formation of molecules of biological interest from formaldehyde and hydroxylamine in a modified sea medium.

As reported previously, glycine, serine, aspartic acid, and beta-alanine are the predominant amino acids produced from equimolecular formaldehyde and hydroxylamine in a modified sea medium enriched with essential transition metal ions. The time course of formation of the amino acids, and related substances was studied. Among the amino acids, glycine was produced earlier. Urea was produced initially and disappeared rapidly. Formation of cyanide, glycinenitrile, and glycinamide preceded the formation of amino acids. Probable pathways for the formation of amino acids and urea are suggested.

Stimulation of cyanide formation by ADP and its possible role in the regulation of nitrate reductase

Stimulation of cyanide formation by ADP and its possible role in the regulation of nitrate reductase

ChemInform Abstract: HYDROGEN CYANIDE PRODUCTION DURING REDUCTION OF NITRIC OXIDE OVER PLATINUM CATALYSTS‐ TRANSIENT EFFECTS

AbstractHydrogenzyanid‐Herstellung während der Reduktion von Stickstoffmonoxid über Platin‐Katalysatoren: Transient Effekte.

Hydrogen Cyanide Production During Reduction of Nitric Oxide over Platinum Catalysts: Transient Effects

The formation of hydrogen cyanide during the catalytic reduction of nitric oxide (NO) with carbon monoxide and hydrogen was studied with a bench-scale flow reactor. The previously reported inhibition by sulfur dioxide of the formation of hydrogen cyanide was found to be counteracted by transient admission of oxygen to the catalyst. These results are discussed in the context of the control of automotive emissions of NO and the prevention of hydrogen cyanide production during such control.

A new channel for the formation of hydrogen cyanide in CH2-N2 systems

Hydrogen cyanide has been observed as a product from the photolysis of the CH2CO-N2 and CH2N2-N2 systems. The rate constant for the reaction of CH2(X3B1) with N2 has been determined to be ⩽10−16 cm3 molecule−1 s−1. A time history of the HCN production has been obtained and a hypothesis advanced to explain its production.

Accumulation of hypothiocyanite ion during peroxidase-catalyzed oxidation of thiocyanate ion.

An oxidized form of thiocyanate accumulated during incubation of lactoperoxidase or myeloperoxidase with thiocyanate ion and low concentrations of peroxide. Addition of one mole of peroxide resulted in loss of one mole of thiocyanate and formation of one mole of the oxidation product. The oxidation product reacted with two moles of sulfhydryl to yield one mole of disulfide and one mole of thiocyanate. The same product was obtained by alkaline hydrolysis of thiocyanogen. The product is proposed to be hypothiocyanite ion. The peroxidases may catalyze the oxidation of thiocyanate to hypothiocyanite, or to thiocyanogen. Hypothiocyanite may be the antimicrobial agent formed during peroxidase‐catalyzed oxidation of thiocyanate.Hypothiocyanite decomposed slowly with a second‐order rate constant of 0.1 M−1 s−1 at 25°C. When the amount of peroxide added approached the amount of thiocyanate, the yield of hypothiocyanite reached a maximum and then declined. This result suggested that hypothiocyanite was oxidized by excess peroxide. Efforts to produce high concentrations of hypothiocyanite were unsuccessful, even when thiocyanate was well in excess of peroxide. As the hypothiocyanite concentration approached 0.5 mM, decomposition was accelerated and small amounts of cyanide were produced. Hypothiocyanite reacted stoichiometrically with cyanide to give products that did not oxidize sulfhydryls. Hydrolysis of thiocyanogen at neutral pH also resulted in rapid decomposition and formation of cyanide.

Cyanide formation from histidine in Chlorella a general reaction of aromatic amino acids catalyzed by amino acid oxidase systems

The formation of HCN from d-histidine in Chlorella vulgaris extracts is shown to be due to the combined action of a soluble protein and a particulate component. Either horse-radish peroxidase (EC 1.11.1.7) or a metal ion with redox properties can be substituted for the particulate component. Ions of manganese and vanadium are especially effective, as are o- phenanthroline complexes of iron. Cobalt ions are less active. The d-amino acid oxidase (EC 1.4.3.3) from kidney and the l-amino acid oxidase (EC 1.4.3.2) from snake venom likewise cause HCN production from histidine when supplemented with the particulate preparation from Chlorella or with peroxidase or with a redox metal ion. The stereospecificity of the amino acid oxidase determines which of the two stereoisomers of histidine is active as an HCN precursor. Though histidine is the best substrate for HCN production, other naturally occurring aromatic amino acids (viz. tyrosine, phenylalanine and tryptophan) can also serve as HCN precursors with these enzyme systems. The relative effectiveness of each substrate varies with the amino acid oxidase enzyme and with the supplement. With respect to this latter property, the particulate preparation from Chlorella behaves more like a metal ion than like peroxidase.

In vitro production of cyanide in normal human blood and the influence of thiocyanate and storage temperature.

Normal human blood stored at room temperature (about 20 degrees C) may, over a period of weeks, undergo a slow transformation of its cyanide content. In contrast, when normal blood is stored at -20 degrees C there is formation of cyanide, usually occurring most rapidly during the first few days of storage. Peak concentrations are never greater than 20 microgram/100 ml, and although some fluctuation in concentration occurs over several months of storage at deep freeze temperature, levels are always higher than in the freshly drawn blood. The amount of cyanide produced appears to be a function of both the initial thiocyanate concentration and the freezing and/or thawing of blood. Blood stored at refrigerator temperature (about 4 degrees C) has the least fluctuation in cyanide concentration over a storage period up to three months. During this study it was found that there is significant difference in whole blood cyanide concentration between smokers and nonsmokers.

Equilibrium studies of sulphur, carbon, oxygen, nitrogen and hydrogen species under the conditions of the reductive sulphur method

High-temperature equilibrium calculations are used in a theoretical study of the interference from nitrogen in the reductive microcoulometric method for trace sulphur determinations. Conditions are outlined which give a high recovery of hydrogen sulphide without the formation of interfering amounts of hydrogen cyanide. In addition to oxygen, argon is useful in suppressing the formation of hydrogen cyanide. Possible mechanisms in the reductive sulphur method are discussed. The theoretical results obtained are compared with some experimental results from the literature.

Pharmacokinetics of cyanide in poisoning of dogs, and the effect of 4-dimethylaminophenol or thiosulfate.

Cyanide in blood, plasma, and urine of dogs after administration of K14CN was determined with the isotope dilution technique. The addition of large amounts of inactive KCN as soon as possible to a sample to be analyzed inhibited the decrease of the original cyanide concentration. After administration of several lethal doses of cyanide into the stomach or by slow intravenous infusion a concentration of about 40 micron cyanide in plasma was found at the moment of respiratory arrest. Since 60% of the cyanide in plasma was bound to proteins the concentration of free cyanide which stopped respiration was about 16 micron. Quick formation of ferrihemoglobin by i.v. injection of 4-dimethylaminophenol after plasma cyanide had risen to or above 40 micron decreased the cyanide concentration in plasma and restored respiration, while cyanide was accumulated in red cells by formation of ferrihemoglobin cyanide. Equilibrium constants calculated for the reaction between ferrihemoglobin and cyanide in vivo indicated that the reaction approached equilibrium in a few minutes. Up to 60% of the radioactive cyanide absorbed was found as non-cyanide radioactivity in the urine.

The formation and destruction of hydrogen cyanide from atmospheric and fuel nitrogen in rich atmospheric-pressure flames

A novel method involving direct sampling of natural flame ions into a mass spectrometer has been used to measure the concentration of HCN, NH 3 and NO in atmospheric-pressure flames. It is found that HCN is formed from N 2 in the reaction zone of rich hydrocarbon flames and is subsequently completely oxidized within the flame, in part to NO. This corresponds to Fenimore's ‘prompt NO’. The amount of HCN formed is proportional to the N 2 concentration, but is not very dependent on the nature of the fuel (CH 4, C 2H 4 and C 2H 2) or on the temperature (between 2000 and 2560 K). It varies strongly with the equivalence ratio and is greater, the richer the flame. In contrast to N 2, nitrogen compounds in the fuel, whatever their nature (NO, NH 3, CH 3CN or pyridine), are converted quantitatively to HCN in the reaction zone of rich hydrocarbon flames. The subsequent disappearance of HCN within the flame has been studied, and between 2300 K and 2560 K the rate is consistent with the reaction CN + OH → NCO + H being the rate-limiting step with a rate constant of approximately 1 × 10 −10 cm 3 molecule −1 s −1, although other mechanisms may be important at lower temperatures.

Hydrogen Cyanide Formation over Automotive Catalytic Converters

Hydrogen Cyanide Formation over Automotive Catalytic Converters

Cyanide formation in preparations from Chlorella vulgaris Beijerinck: Effect of sonication and amygdalin addition

A critical evaluation of a method for recovering HCN from cell extracts is presented. Since crude extracts often bind or metabolize HCN extensively, the HCN recovered by distillation at room temperature represents only the difference between production and consumption. Sonication leads to HCN release from the alga, Chlorella vulgaris Beijerinck. Illumination of extracts at high light intensity in oxygen, with added Mn(2+) and peroxidase, also stimulates HCN production. In both processes, the HCN is probably formed by oxidation of nitrogenous precursors. Chlorella extracts cause formation of HCN from added amygdalin. No evidence was found, however, for the presence of cyanogenic glycosides in the algae.

Cyanide formation in preparations from Chlorella and New Zealand spinach leaves: Effect of added amino acids

As part of an effort to identify the natural precursor(s) of HCN in the alga Chlorella vulgaris Beijerinck, and in leaves of New Zealand spinach (Tetragonia expansa, Murr.), HCN release was measured after addition of various amino acids to illuminated algal extracts and grana preparations. Histidine is particularly effective as an HCN precursor, both with Chlorella extracts and leaf grana. With the algal extracts, D-histidine is about ten times more effective than L-histidine and histamine, whereas the two isomers (and histamine) are about equally effective with leaf grana. In the presence of leaf grana plus added Mn(2+) and peroxidase, L-tyrosine and L-cysteine like-wise cause HCN formation; but these amino acids cause little or no HCN formation in the presence of Chlorella extracts. A stimulation of HCN production by L-histidine was observed with intact Chlorella cells. Because of the limitations of the assay method, the possibility can not be excluded that other substances than histidine may also lead to HCN generation in Chlorella vulgaris, but the results show that histidine has an important role in HCN generation by this species.

The Radiation Synthesis of Hydrogen Cyanide from the Nitrogen–ethylene System. The Effect of Fission-fragment Irradiation

Abstract Upon irradiation by (FF+n+γ), the G(HCN) value from the nitrogen-ethylene system increased with the rise in the pressure, while upon y and (n+γ) radiations it decreased. This pressure effect was explained in terms of the high concentration of the active species in the FF tracks. At a high pressure, Reaction (5) is considered to take place in the tracks; &N_2^++e^-→2N\ ag5 \intertextAt low pressures, Reaction (6) predominates, as in the γ-ray radiolysis, over Reaction (5) even in the FF tracks, &N_2^++C_2H_4→N_2+C_2H_4^+\ ag6 and nitrogen molecule cations do not contribute to the formation of hydrogen cyanide.

Glutathione S-transferase in the formation of cyanide from organic thiocyanates and as an organic nitrate reductase

Evidence is presented that glutathione S-transferases, a group of enzymes active in the formation of thioethers from glutathione and a large number of compounds with an electrophilic carbon atom, can also catalyze the formation of nitrous acid and oxidized glutathione from organic nitrate esters such as nitroglycerin. In addition, organic thiocyanates are cleaved by these enzymes to form cyanide and the respective asymmetric disulfide of glutathione.

Characterization of some gem-dinitrilo sneeze and tear gases by electron-impact induced fragmentation.

Reaction products obtained during the decomposition of somegem dinitrilo sneeze and tear gases upon electron-impact are described. The spectra of benzal,o-chloro, andm-nitro malonitriles show some common characteristics which can be used for identification and characterization of these compounds. These are: (a) a base peak at [M-substituted atom or group]+; (b) diagnostic intense peak at m/e 76 and 77 due to C2H(CN)2 and C2(CN)2 besides other cyano fragmentation products; and (c) rearrangement reaction lead-ing to the formation of phenyl cyanide.

Formimidoyl cyanide and isocyanide from azidoacetonitrile by photolysis

Photoelimination of nitrogen from azidoacetonitrile (1) produced formimidoyl cyanide (2). At –196 °C further irradiation transformed the cyanide (2) into formimidoyl isocyanide (3); both (2) and (3), detected by i.r. absorption, can be intermediates in the formation of hydrogen cyanide and adenine (4) from a solution of (1) irradiated at 25–40 °C. Photodissociation of N-ethyl-(5a), N-isopropyl-(5b), and N-t-butyl-formimidoyl cyanide (5c) gave the corresponding N-alkyl isocyanide (7a–c)(3 %) at 25–40 °C and in detectable amounts at –196 °C. Azidoacetonitrile (1) at 125 °C dimerised to give 5H,10H-ditetrazolo[1,5-a:1′,5′-d]pyrazine(15).