Hydrocyanic acid properties

A general property of aldehydes and ketones is that when heated with hydrocyanic acid, additive compounds, termed nitriles or cyanohydrins, are produced, according to the general equations—... 

Glycosides that have soaplike properties are called saponins. Similarly, glycosides that liberate hydrocyanic acid (HCN) on hydrolysis are known as cyanogenic glycosides, and glycosides that have an effect on heart muscle are called cardiac glycosides. 

The discovery of Liebig, that when hydrocyanic acid was mixed with sulphide of ammonium, and subjected to a moderate degree of heat, a compound— snlphocyanide of ammonium—was formed, which possessed the property of giving an intense blood-red color with the sesquisalts of iron, afforded a test for hydrocyanic acid, which is equal, if not superior, to any at present known, Dr, Pereira remarks —When the acid is in small quantity, and mixed with solids or... 

Hydrogen cyanide, HCN, is also known as hydrocyanic acid, prussic acid and formonitrile. Although HCN is a colorless liquid, iron cyanide is blue (Prussian blue) and its presence as a slight contaminant usually gives HCN a bluish tint that led to the German name Blausaure - blue acid. Selected physical properties of hydrogen cyanide are shown in Table 19.1. 

To emphasize the concept of base strength, consider the basic properties of the cyanide ion. One relevant reaction is the dissociation of hydrocyanic acid in water ... 

This form of alteration has raised the problem of stabilisers, that is, substances which when added in quite small quantity, preserve the aggressive properties of the gas. For some of these gases, as acrolein, hydrocyanic acid, etc., efficient stabilisers are... 

With the aid of this theory it is explained that just as in coloured substances the introduction of some auxochromic groups changes the colour of the substances, so in the war gases the presence of certain autotoxes can alter the type of biological action. Thus, for example, halogen introduced into the hydrocyanic acid molecule reduces the toxicity of the toxophor, —CN, and confers on the product lachrymatory properties. 

So far as the physiopathological properties have been studied it has been observed that the iodo- derivatives are more toxic than the bromo-compounds and are also more poisonous than hydrocyanic acid. The toxic action exhibited by substances of this class has been attributed to the presence of the divalent carbon atom which, as already mentioned, has a greater chemical affinity than tetravalent carbon. 

In this case, use is made of the property of very dilute, gaseous hydrochloric acid of reacting with mercuric cyanide, liberating an equivalent quantity of hydrocyanic acid, while phosgene does not do this. ... 

Because of its strongly irritant properties, it has been used in insecticidal preparations " Zyklon A, which is a mixture of 90% of methyl cyanoformate and 10% of methyl chloroformate, and Zyklon B, a mixture of liquid hydrocyanic acid and irritant chlorinated and brominated compounds. ... 

The Michael addition of anions of C-acids, such as acetylacetone or hydrocyanic acid, to phenyl vinyl ketone follows a scheme similar to (7). In the cases studied it was possible to neglect the acid-base properties of the adduct and the reverse elimination reaction (Hrubcova, 1964). Equations analogous to (9) and (10) were used and the pH-dependence of the determined formal rate constant at a given analytical concentration of the C-acid follows a dissociation curve with an inflexion at the pKa value of the C-acid. 

Properties Needles odor resembles that of hydrocyanic acid. Stable at 0C, unstable at normal temperature. Small quantities volatilize, large quantities decompose. Aqueous solutions slowly decompose. Soluble in water, alcohol, ether, benzene shghtly soluble in carbon disulfide. 

Macy, R. (1937). Hydrocyanic acid Its military history and a summary of its properties (Edgewood Arsenal Tech. Rep. No. 219). Edgewood Arsenal, MD War Department, Chemical Warfare Service. (DTIC No. AD-B957 032)... 

HCN has the chemical synonyms of formonitrile, pmssic acid, and hydrocyanic acid. Some physicochemical properties are compared with those of the sodium, potassium, and calcium salts in Table 14.1. Relevant to the toxicity and hazards of HCN are its hquid state at NTP, poor ionization, low molecular weight (MW), low boiling point, high vapor pressure, low vapor density (0.947 at 31°C), and hence ready diffusibility. The salts are sohds that are readily soluble in water, ionize, and in spite of low vapor pressure they hydrolyze in moist conditions with the hberation of HCN, this being markedly increased under acidic conditions. 

Hydrogen cyanide (HCN) is also chemically identified by the synonyms formonitrile, prussic acid and hydrocyanic acid. The physicochemical properties most related to the biological activity and uses of HCN are summarized in Table 1. Notable with HCN is that it is a low boiling point liquid (26.5°C). Related to its low MW (27.04) it has a high vapor pressure (600 mm Hg at 20°C) and low vapor density (0.947 at 31°C), Thus,... 

It is usually met with in dull, white, amorphous masses odorless when dry, it-bas the odor of hydrocyanic acid when moist It is deliquescent, and very soluble in H,0 almost insoluble in alcohol Its solution is acrid, and bitter in taste, with an after-taste of hydrocyanic acid. It is very readily oxidized to the cysxuste, property which renders it valoable as a reducing agent. Solntions of CN dissolve Agd, the cyanides of Ag and Au, and many metallic oxides. 

Warburg,11 who suggested that cell respiration is catalyzed by heavy metals contained in living cells, observed that chemicals that poison such action also inhibit similar catalytic properties in charcoal. Thus, hydrocyanic acid poisons living cells and also the catalytic properties of carbon. Both effects are ascribed to adsorption on active centers that contain iron. 

MSS (abont 200 to 400 pg from a cigarette delivering 15 to 25 mg of FTC tar ), its toxicity (other than ciliastasis) when examined alone, and the fact that consumers would be more familiar with the toxic properties of hydrogen cyanide (also known as hydrocyanic acid or cyanide ) than with the toxic properties of MSS components such as acrolein or phenol. Most of the effort dnring this period dealt with filter-tip additives other than carbon. 

Hydrocyanic acid is a colorless liquid which boils at 26°, and when cooled forms crystals which melt at —14°. It has an odor which is similar to that of the oil of bitter almonds. It burns with a pale blue flame. Hydrocyanic acid is one of the most powerful poisons 0.05 gram is said to be a fatal dose. Hydrogen peroxide or the inhalation of air containing chlorine are said to be antidotes for hydrocyanic acid. The poisonous property of the acid is in some way associated with the CN ion. Substances from which this ion is produced are poisonous,whereas those, like potassium ferrocyanide, which do not give a simple CN ion are not poisonous. 

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