From Big Medical Encyclopedia

CYANIC CONNECTIONS — chemical compounds, the molecule to-rykh contains one or several cyanogroups (C=N). Salts of cyanhydric acid (see) — cyanides, including complex cyanides, and also organic compounds with the general formula X — C=N where X — Cl, Br, CN, etc. belong to cyanic connections. Cyanic connections are, as a rule, highly toxic; many C. pages are industrial poisons. Nek-ry natural glycosides (see), enzymatically or chemically hydrolyzed with education hydrocianic to - you, and also nitriles belong to cyanic connections (see).

From C. pages in biochemical clinical diagnostic laboratories are most often applied cyanic potassium and sodium — cyanides of alkali metals (see). These salts are thermally steady, well rastvorima in water, in water solutions they are hydrolyzed to such an extent that these solutions remind mix of caustic alkali and hydrocianic to - you. In a firm look and in solution under the influence of carbon dioxide cyanic potassium and sodium gradually decay with allocation hydrocianic to - you: 2KCN + C02 + + H20 -> K2C03 + 2HCN. Cyanides of alkaline earth metals (see) have similar properties. Cyanides of heavy metals, e.g. CuCN, AgCN are thermally unstable, in water are insoluble. The cyanide and oxycyanide of bivalent Hg (CN) 2 and Hg (CN) 2*H20 mercury of a rastvorima applied in medicine as antiseptic agents in water, but owing to very small extent of dissociation practically do not form an ion of CN"; to-tami they decay to HCN. Reactions of transformation of cyanides into thiocyanates, or rhodanates (KCN -> f-S — KGNS), and oxidations in cyanates (KCN + About —> KOCN) can serve

for neutralization of C. page, including in a human body. Alkaline cyanides form with cations of many metals complex salts, stability to-rykh depends by nature metal-kompleksoobra-zovatelya. To the most known C. pages of this type belong hexacyanoferrate (P) of K4Fe (CN) 6 potassium (a synonym: potassium ferrocyanide, potassium ferrocyanide, yellow blood salt) and hexacyanoferrate (Sh) of K3Fe (CN) 6 potassium (synonym: red prussiate of potash, ferricyanide of potassium, red blood salt). Complex anions of these salts are very strong (do not give reactions to CN”) in this connection they are malotoksichna, however heating with mineral to-tami leads to their decomposition with education hydrocianic to - you that should be considered during the work with yellow and red blood salt; hexacyanoferrate (Sh) of potassium oxidizes hemoglobin in a methemoglobin. Sodium nitroprussidum of Na2FeNO (CN) 5 which is easily chipping off CN-is strongly poisonous.

The cyanogen halides (acid halides cyanic to - you are HOC=N) received at interaction of alkaline cyanides or HCN with halogens: NaCN + X2 — >NaX + XCN, where X. — C1, Vg or I. are highly toxic like cyanhydric acid and possess strong tear action.

Cyanogen chloride at a usual temperature — the gas relating to all-toxic toxic agents (see), g°pl-6,90, / °ki11+12,6 °. Cyanogen bromide (g°pl52 °, g°kip61,6 °) and iodo-cyanogen (sublimating temperature apprx. 136 °) — the colourless, easily sublimated crystals. Fluorine cyanide — gas, at chemical and biochemical researches is used seldom. Cyanogen chloride is applied in industrial organic synthesis, cyanogen bromide — in biochemistry as reagent at fragmentation of proteins and activation of hydroxylic groups at receiving adsorbents to an affine chromatography (see). Oxalonitrile [cyan, (CN)2] — colorless gas with a pungent smell, g°ksh1 — 20,7 °, water soluble, is formed as a result of thermal decomposition of cyanides of heavy metals or exchange reactions, meets as a by-product at nek-ry organic reactions, in domain and illuminating gases, in trace quantities contains in tobacco smoke. On character and degree of toxicity it is similar to cyanhydric acid.

Trace amounts of cyanides (micrograms and less), and also cyanogen halides in biol. liquids, water, etc. define photometric (see Photometry) by highly sensitive staining reactions and other methods.

In detail qualitative and quantitative test of cyanides, cyanides as professional harm and cyanides in the medicolegal relation — cm. Cyanhydric acid.

Bibliography: Harmful substances in the industry, under the editorship of N. V. Lazarev and I. D. Gadaskina, t. 3, page 260, D., 1977; Nekrasovb. B. Fundamentals of the general chemistry, t. 1, M., 1973. A. I. Tochilkin.