Hydrocyanic acid cyanide

Hydrocyanic acid - [CYANIDES] (Vol 7) -atmospheric synthesis [IMINES, CYCLIC] (Vol 14)... 

Odour of hydrocyanic acid—cyanide, ferro- or ferri-cyanide. 

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequendy used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkaU catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonittile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkaU metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Grignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

Mandelic acid is best prepared by the hydrolysis of mandeloni-trile with hydrochloric acid. The mandelonitrile has been prepared from amygdalin, by the action of hydrocyanic acid on benzaldehyde, and by the action of sodium or potassium cyanide on the sodium bisulfite addition product of benzaldehyde. ... 

Mandelic Acid.—The reaction furnishes a simple and general method for obtaining hydroxy-acids from aldehydes or ketones by the aid of the cyanhydrin. The formation of the cyanhydrin may be effected in the manner described or by the action of hydrochloric acid on a mixture of the aldehyde or ketone with potassium cyanide, or, as in the case of the sugais, by the use of liquid hydrocyanic acid and a little amme-nia. 

Hydrocyanic acid may be approximately estimated by dissolving 1 gram of oil in 5 c.c. of alcohol, and adding 50 c.c. of water. Then add ammonio-silver nitrate solution and shake well. Acidify slightly with nitric acid, and collect, wash, and dry the silver cyanide precipitated. Ignite and weigh the silver, 4 parts of which correspond to practically 1 of hydrocyanic acid. 

Cyan-verbindung, /. cyanogen compound, -verg tung,/. cyanogen poisoning, -wasser-stoff, m. hydrogen cyanide hydrocyanic acid. 

Hydrogen cyanide (hydrocyanic acid) is a colorless liquid (b.p. 25.6°C) that is miscible with water, producing a weakly acidic solution. It is a highly toxic compound, but a very useful chemical intermediate with high reactivity. It is used in the synthesis of acrylonitrile and adiponitrile, which are important monomers for plastic and synthetic fiber production. 

As early as 1908, Rosenthaler found in the ferment mixture of emulsin a u-oxynitrilase , which directed the addition of hydrocyanic acid (hydrogen cyanide) to benzaldehyde asymmetrically to give x-hydroxybenzeneacetonitrilc (mandelonitrile)9. This result was confirmed1 °, however, it was not until 1963 that Pfeil ct al. first isolated and characterized the enzyme (R)-oxyni-trilase [EC 4.1.2.101 from bitter almonds (Prunus amygdalus)1 12. The yellow-colored enzyme contains a flavin-adenine dinucleotide (FAD)11 and loses its activity by splitting off this prosthet-... 

Nitriles are organic derivatives of hydrocyanic acid in which the substituting group is attached to carbon. Their formula is R.C N. Because most nitriles can be derived from corresponding acid amides, R.CO.NH2, by removal of w, they are called nitriles. For instance, the compd CH3.CN is called acetonitrile because it is derived from acetamide. It can also be called methyl cyanide. The compd C2HS.CN is called either propionitrile or ethyl cyanide, etc The first nitrile to be prepared was propionitrile which J. Pelouze obtained in 1834 by distg Ba ethyl sulfate with K cyanide... 

Another example of an acid is hydrogen cyanide, HCN, which transfers its proton to water when it dissolves to form the solution known as hydrocyanic acid, HCN(aq). However, only a small fraction of the HCN molecules donate their protons, and so we classify HCN as a weak acid in water. We write the proton transfer reaction with equilibrium half-arrows ... 

There is a discrepancy between the cyanide criteria for both aquatic and drinking water standards and the current analytical technology. The criteria are stated for free cyanide (which Includes hydrocyanic acid and the cyanide ion), but the EPA approved analytical methodology for total cyanide measures the free and combined forms (11). This test probably overestimates the potential toxicity. An alternative method (cyanides amenable to chlorination) measures those cyanide complexes which are readily dissociated, but does not measure the iron cyanide complexes which dissociate in sunlight. This method probably tends to underestimate the potential toxicity. Other methods have been proposed, but similar problems exist (12). The Department of Ecology used the EPA-approved APHA procedure which includes a distillation step for the quantification of total cyanide (13,14). A modification of the procedure which omits the distillation step was used for estimation of free cyanide. Later in the study, the Company used a microdiffusion method for free cyanide (15). 

Free cyanide is the primary toxic agent in the aquatic environment. Free cyanide refers to the sum of molecular HCN and the cyanide anion (CN ), regardless of origin. In aqueous solution with pH 9.2 and lower, the majority of the free cyanide is in the form of molecular HCN. The chemical names for HCN include hydrogen cyanide, hydrocyanic acid, cyanohydric acid, and prussic acid. 

Hydrogen cyanide (Table 15.1) is a colorless, flammable liquid or gas that boils at 25.7°C and freezes at minus 13.2°C. The gas rarely occurs in nature, is lighter than air, and diffuses rapidly. It is usually prepared commercially from ammonia and methane at elevated temperatures with a platinum catalyst. It is miscible with water and alcohol, but is only slightly soluble in ether. In water, HCN is a weak acid with the ratio of HCN to CN about 100 at pH 7.2, 10 at pH 8.2, and 1 at pH 9.2. HCN can dissociate into H+ and CN. Cyanide ion, or free cyanide ion, refers to the anion CN derived from hydrocyanic acid in solution, in equilibrium with simple or complexed cyanide molecules. Cyanide ions resemble halide ions in several ways and are sometimes referred to as pseudohalide ions. For example, silver cyanide is almost insoluble in water, as are silver halides. Cyanide ions also form stable complexes with many metals. 

Simple cyanides typically refer to alkali water-soluble salts, such as NaCN, KCN, Ca(CN)2, and Hg(CN)2, but also include several cyanide salts of alkali, alkaline earth, or heavy metals, that is, Zn(CN)2, Cd(CN)2, Ni(CN)2, and AgCN, of varying degrees of solubility. In water, NaCN and KCN will completely dissociate to give free cyanide. All simple cyanides ionize in water to release cyanide ion which, depending on pH, will form hydrocyanic acid. For sodium cyanide, the reaction proceeds as follows ... 

Casadei, E., P. Jansen, A. Rodrigues, A. Molin, and H. Rosling. 1984. Mantakassa an epidemic of spastic paraparesis associated with chronic cyanide intoxication in a cassava staple area of Mozambique. 2. Nutritional factors and hydrocyanic acid content of cassava products. Bull. World Health Org. 62 485-492. 

The precise technical name of HCN is Hydrocyanic Acid. The cyanides are true protoplasmic poisons, combining in the tissues with the enzymes associated with cellular oxidation. They thereby render the oxygen unavailable to the tissues, and cause death through asphyxia. Inhaling concentrations of more than 180 ppm of HCN will lead to unconsciousness in a matter of minutes, but the fatal effects would normally be caused by carbon monoxide poisoning after HCN has made the victim unconscious. Exposure to HCN concentrations of 100 to 200 ppm for periods of 30 to 60 minutes can also cause death. 

HYDROGEN CYANIDE, LIQUEFIED ICSC 0492 HYDROGEN CYANIDE, LIQUEFIED Hydrocyanic acid Prussic acid (liquefied)... 

Synonym(s) Formonitrile hydrocyanic acid prussic acid Cyanide of sodium hydrocyanic acid sodium salt Cyanide of potassium hydrocyanic acid, potassium salt Calcid calcyan cyanide of calcium... 

Aletor VA. 1993. Cyanide in garri. 1. Distribution of total, bound and free hydrocyanic acid in commercial garri, and the effect of fermentation time on residual cyanide content. Int J Food Sci Nutr 44(4) 281-287. 

Fairley A, Linton EC, Wild FE. 1934. The absorption of hydrocyanic acid vapour through the skin with notes on other matters relating to acute cyanide poisoning. J Hyg 34 283-294. 

Remarks on Sections 6 and 7.-—The method here described for the synthesis of cyanohydrins—treatment of the bisulphite compound of the aldehyde with potassium cyanide—cannot be used in all cases. Concentrated solutions of hydrocyanic acid or anhydrous hydrogen cyanide are often used. The general method for the synthesis of a-amino-acids, the nitriles of which are formed by the union of ammonium cyanide with aldehydes or ketones (Strecker), is to be contrasted with that for the synthesis of a-hydroxy acids. For additional amino-acid syntheses see Chap. VII. 2, p. 276. 

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