Hydrogen cyanide, atmosphere

Hartzell, G.E. Stacy, H.W. Switzer, W.G. Priest, D.N. "Modeling of Toxicological Effects of Fire Gases V. Mathematical Modeling Intoxication of Rats by Combined Carbon Monoxide and Hydrogen Cyanide Atmospheres," J. Fire Sciences 1985, 3(5), 330-342. 

In the final step the dinitrile is formed from the anti-Markovrukov addition of hydrogen cyanide [74-90-8] at atmospheric pressure and 30—150°C in the hquid phase with a Ni(0) catalyst. The principal by-product, 2-methylglutaronitrile/4j5 j5 4-ti2-, when hydrogenated using a process similar to that for the conversion of ADN to hexamethylenediamine, produces 2-meth5i-l,5-pentanediamine or 2-methylpentamethylenediamine [15520-10-2] (MPMD), which is also used in the manufacture of polyamides as a comonomer. 

Some hydrogen cyanide is formed whenever hydrocarbons (qv) are burned in an environment that is deficient in air. Small concentrations are also found in the stratosphere and atmosphere. It is not clear whether most of this hydrogen cyanide comes from biological sources or from high temperature, low oxygen processes such as coke production, but no accumulation has been shown (3). 

Hydrogen cyanide is a weak acid and can readily be displaced from a solution of sodium cyanide by weak mineral acids or by reaction with carbon dioxide, eg, from the atmosphere however, the latter takes places at a slow rate. 

The use of black cyanide as a fumigant and rodenticide makes use of the atmospheric humidity action that Hberates hydrogen cyanide gas. It can only be used effectively ia confined spaces where hydrogen cyanide builds up to lethal concentrations for the particular appHcation. Black cyanide is also used ia limited quantities ia the production of pmssiates or ferrocyanides (see Iron compounds). 

Emissions to the atmosphere from ammonia plants include sulfur dioxide (SOj), nitrogen oxides (NOJ, carbon monoxide (CO), carbon dioxide (COj), hydrogen sulfide (HjS), volatile organic compounds (VOCs), particulate matter, methane, hydrogen cyanide, and ammonia. The two primary sources of pollutants, with typical reported values, in kilograms per ton (kg/t) for the important pollutants, are as follows ... 

Hydrogen cyanide is a reactant in the production of acrylonitrile, methyl methacrylates (from acetone), adiponitrile, and sodium cyanide. It is also used to make oxamide, a long-lived fertilizer that releases nitrogen steadily over the vegetation period. Oxamide is produced by the reaction of hydrogen cyanide with water and oxygen using a copper nitrate catalyst at about 70°C and atmospheric pressure ... 

Direct acidihcation of cyanide waste streams was once a relatively common treatment. Cyanide is acidified in a sealed reactor that is vented to the atmosphere through an air emission control system. Cyanide is converted to gaseous hydrogen cyanide, treated, vented, and dispersed. 

As already mentioned, hydrogen cyanide is formed in simulation experiments using reducing primeval atmospheres. CN was discovered in interstellar space as early as 1940 by optical spectroscopy (Breuer, 1974), and later HCN itself (from measurements using millimetre wavelengths). Only a few years after the Miller-Urey experiments, Kotake et al. (1956) obtained HCN in good yields by reacting methane with ammonia over aluminium-silicate contacts ... 

In spite of the complexity of dealing with atmospheres containing multiple toxicants, considerable progress has been made in understanding some of the effects from studies using rodents. For example, it is fairly well agreed that carbon monoxide and hydrogen cyanide appear to be additive when expressed as fractional doses required to cause an effect (21,22). Thus, as a reasonable approximation, the fraction of an effective dose of CO can be added to that of HCN and the time at which the sum becomes unity (100%) can be used to estimate the presence of a hazardous condition. 

Hydrogen cyanide has frequently been associated with the odor of bitter almonds (Ballantyne 1983 Gee 1987). The threshold odor for olfactory detection of atmospheric HCN is 1 mg/L, but the odor may not be detected for various reasons, including the presence of other odors and the fact that only 20 to 40% of those tested could detect a cyanide odor. 

Cardiovascular Effects. Peripheral vasoconstriction and gross plasma extravasation were reported in a man who accidentally fell into a cistern with hot copper cyanide (Dodds and McKnight 1985). Palpitations were recorded in 3 men who wore respiratory masks while working in an atmosphere containing 20,000 ppm hydrogen cyanide for 8-10 minutes (Drinker 1932). The masks were reported to give excellent respiratory protection. Therefore, the effects seen in these men may have been due to dermal exposure. 

Environmental Fate. The environmental fate of hydrogen cyanide gas in air is well studied (Cicerone and Zellner 1983 Fritz et al. 1982) however, it would be useful if the role of particulate cyanides (e.g., sodium cyanide, potassium cyanide) in determining the fate of total cyanides in the air was known. Given that hydrogen cyanide occurs in the atmosphere from both natural and anthropogenic processes (Cicerone... 

Cicerone RJ, ZellnerR. 1983. The atmospheric chemistry of hydrogen cyanide (HCN). JGeophysRes 88 10689-10696. 

Irradiation of toluene (80 ppm) by UV light (A, = 200-300 nm) on titanium dioxide in the presence of oxygen (20%) and moisture resulted in the formation of benzaldehyde and carbon dioxide. Carbon dioxide concentrations increased linearly with the increase in relative humidity. However, the concentration of benzaldehyde decreased with an increase in relative humidity. An identical experiment, but without moisture, resulted in the formation of benzaldehyde, carbon dioxide, hydrogen cyanide, and nitrotoluenes. In an atmosphere containing moisture and nitrogen dioxide (80 ppm), cresols, benzaldehyde, carbon dioxide, and nitrotoluenes were the photoirradiation products (Ibusuki and Takeuchi, 1986). 

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