Cyanides formation

Thermal decomposition under hydrogen of a series of pentacyanocobaltate complexes (CN-, N02-, NO- or N3-ligands) revealed that the latter complex is the most exothermic by far. Presence of iron powder suppresses hydrogen cyanide formation. 

The ferrocyanide complex is not easily biodegradable (Belly and Goodhue 1976 Pettet and Mills 1954). However, when an aqueous solution of potassium ferrocyanide was seeded with pure culture of Pseudomona aeruginosa, E. coli, or a mixture of the two bacteria, formation of free cyanide was observed after a delay period of 2 days (Cherryholmes et al. 1985). The rate of free cyanide formation increased with addition of nutrient in water, and a free cyanide concentration <4,000 pg/L was detected at the end of 25 days. It was shown that the free cyanide formation was due to biodegradation and not to either photolysis or hydrolysis. The relevance of this study to the fate of ferrocyanide complexes in natural water or industrial effluents is difficult to assess because cyanide concentrations used in these experiments (3,300 mg/L) are rarely encountered in these media. 

The U S. EPA is funding research at Emec Consultants, Export, Pennsylvania, on methods to the suppress or eliminate cyanide formation in spent potlining from industrial primary aluminum production cells. Because over 100,000 tons of this material are disposed in landfills annually, it would be desirable to avoid the formation of cyanide during the production of the cells. 

The efficiency of the spectrally sensitized cyanide formation was monitored by the estimation of the photochemical turnover number U instead of the quantum yield for practical reasons. 

The results summarized in Table II illustrate the increase of the photo induced formation of cyanide achieved by IT excitation of Cu( 11 )/tMo(CN)g]4 as compared with K [Mo(CN)g]. However, despite the increase of cyanide formation the efficiency of the spectral sensitization is rather low. The low efficiency is due to the circumstance that the rate (k ) o cyanide aquation in the valence isomeric form Cu( I)/TMo(CN)gl is low compared with the very fast back electron transfer (k ).°ln order to make the proper choice of a scavenging reaction (k ) which may compete successfully with back electron transfer, we have attempted a rough estimate of the rate constant k of the back electron transfer following the theoretical treatment proposed by Hush (20). 

Following a similar motivation, a schematic flow scheme of a miniplant for hydrogen cyanide formation via the Degussa route was proposed in [30],... 

Cyanide Formation of cyanohydrins Titration Toxic reagents, overestimation [85]... 

Tuovinen, H., Blomqvist, P., and Saric, F. Modelling of hydrogen cyanide formation in room fires. Fire Safety Journal, 2004. 39(8), 737-755. 

When l-[14C]methyl-pyridinium aldoxime iodide or radioactive pralidoxime [14C]-labelled in the oxime group was parenterally administrated to rats, 90% of the radioactivity was recovered in urine and 6% in the faeces, irrespective of the position of the label. About 90% of the urinary radioactivity was associated with intact pralidoxime. In addition, some 5% of the dose was excreted as l-methyl-2-pyridone, indicating some cyanogenesis (Enandcret al., 1962). In humans, the l-methyl-2-cyanopyridinium ion was detected in urine of male volunteers without significantly increased urinary thiocyanate. Since 90% of pralidoxime chloride, 5 mg kg 1 IV, was recovered from urine, cyanide formation is probably of no toxicological concern (Garrigue etal., 1990). 

Scheme 1. Parallel degradation pathways forpralidoxime leadingto cyanide formation underbasic pH conditions. (Reproduced from Ref. 1 with permission.)...

Johnson, W.R. and J.C. Kang Mechanisms of hydrogen cyanide formation from the pyrolysis of amino acids and related compounds J. Org. Chem. 36 (1971) 189-192. 

Koji, T, M. Risa, F. Masahiro, and T. Hideki A pyrolysis study on hydrogen cyanide formation in tobacco smoke 56th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 56, Paper No. 76, 2002, pp. 66-67. 

Physicochemical properties of cyanogen (NC—CN, 1) were the subject of thorough investigations. Papers published deal with Raman spectra, with proton affinity, reactions with low-energy electrons " and cyanide formation by electron attachments. Kinetics of basic hydrolysis of cyanogen were investigated in detail. Photolysis at 193 nm was studied... 

The lethal effect of acrylonitrile increased in rats when coadministered with organic solvents (Gut et al. 1981), although the latter decreased the formation of cyanide. Metabolic cyanide formation was found to play only a minor role in the inhalation toxicity of acrylonitrile (Peter and Bolt 1985). This was in contrast to the toxicity of methylacrylonitrile, where the observed clinical symptoms suggest a metabolically formed cyanide. 

Hydrogen cyanide formation may contribute to the toxicity of snake venom, owing to the high levels of L-amino acid oxidase in some snake venoms. This enzyme is harmless on injection, but the tissue destruction caused by other venom components probably provides the required substrate and cofactor for HCN production. Cyanide inhibits ion... 

Separations at high pH common anions, silicate, borate, cyanide, formate, acetate... 

Complete cyanide recoveries are typically attained for the most important metal-cyanide complexes found in environmental samples. Detection limits below 0.05 pg/1 have been reported. The main drawback of this system is that the UV radiation promotes thiocyanate decomposition, what leads to sulfide and cyanide formation. To overcome this problem, it is recommended to use borosilicate glass instead of a quartz reactor, which cuts off radiation below 300 nm. 

Cyanide Formation of a blue dye from reaction of cyanogen chloride, CNCl, with p5Tidine-pyrazolone reagent, measured at 620 mn... 

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