CYANHYDRIC ACID

From Big Medical Encyclopedia

CYANHYDRIC ACID (synonym: hydrocyanic acid, formonitrile) — solution of HCN hydrogen cyanide in water, the strongest poison, blocks cellular respiration at the stage catalyzed by cytochrome oxydase (KF 1.9.3.1) therefore the sharp fabric hypoxia develops. Page to. treats all-poisonous to toxic agents (see). Nek-ry salts C. to. — Cyamidum (see), mercuric cyanide the main, etc. — is applied in medicine as pharmaceuticals, its solutions use for disinfection, fight against rodents, etc. In production of synfils, butadiene-nitrile rubber, plastic, organic glass, etc. also apply S. to. In these productions of S. to. and others cyanic connections (see) represent professional harm.

In S.'s nature to. the hl meets in free, but. obr. in chemically connected state in nek-ry plants, in the form of a glycoside dl-mandelonitrile gentiobioside (see) it contains in almonds, stones of cherries, apricots, peaches, plums and other fruits. S. is found to. and in tobacco smoke.

Anhydrous S. to. represents a volatile easily mobile colorless liquid with t°kip + 25,7 °, t°pl — 134 °, edges mixes up with water and with the majority of organic solvents. Page to. possesses a characteristic smell of bitter almonds.

S.'s structure to. and its main chemical properties answer the nitrile H — C≡N form (see. Nitriles ), however nek-ry features of chemical behavior and high toxicity of S. to. are explained by its tautomeric isonitrile form C better - ≡N + — N, abundance cover in S. to. 0,5 — 1%. At neutralization by alkalis C. to. forms salts — cyanides, however S. to. — very weak to - that, from the salts it is forced out even coal and boric to-tami. Page to. forms complex connections with salts of many metals, including iron, than and blocking of a metalloprotein of cytochrome oxydase at S.'s poisonings is caused to., and also formation of a tsianmetgemoglobin from a methemoglobin. In the presence of traces of acids anhydrous S. to. it is stable, under the influence of the bases, and also in water solutions it will be polymerized. Mineral to-tami S. to. it is hydrolyzed to formic acid (see). Addition reactions of S. to. on carbonyl group aldehydes (cm.) and ketones (see) to the activated double bonds, to epoxy and other connections are widely used in laboratory and industrial organic synthesis.

Page to. receive by means of high-temperature catalytic reaction of methane with ammonia and oxygen, in laboratory — processing of alkaline cyanide or ferricyanide strong to - that, and also dehydration forms yes.

For qualitative test of S. to. staining reactions, napr serve, to reaction of formation of Prussian blue, rhodanate of trivalent iron, etc. Quantitatively S. to. determine by titration in alkaline solution caustic silver (Libikh's method), in trace amounts of S. to. define photometric (see. Photometry ), gas-liquid chromatography (see), polyarografiya (see) and other methods.

Getting to an organism, S. to. and its salts are soaked up in went. - kish. a path within several seconds, penetration of poison into an organism through skin happens more slowly. Page to. quickly collapses in an organism; its main metabolites are less toxic rhodanates, to-rye are formed under the influence of enzyme of a rodaneza (KF 2.8.1.1). It is experimentally shown that the greatest number of rhodanates is removed with urine for the 2nd day after single introduction of HGN. S. entered into an organism to. partially is oxidized to CO2 carbonic acid through cyanic to - that HCNO. After S.'s introduction to. an experimental animal it is found in the air exhaled by them. In experiences with H 14 CN is shown that 14 With joins in a row biologically active compounds — sincaline (see), methionine (see), cyanocobalamine (see).

Professional

Hydrogen cyanide can be emitted to harm in air of workrooms at S.'s receiving to., benzene, a xylol and toluene, cyanic connections (potassium cyanide and sodium, cyanogen chloride, cyanogen bromide, etc.), rhodanates, oxalic to - you, at a galvanoplastic covering of surfaces of metals gold, silver and copper, and also on coke-chemical productions, during the burning of celluloid, incomplete combustion and dry distillation of organic nitrogenous matters, at action on proteins concentrated nitric and sulfuric to-tami, etc. It can be present at blast-furnace gas, at rinsing waters at gas purification, etc.

Toxic action of HCN and other tsrganisty connections capable to dissociate in an organism with formation of an ion of CN" is based almost entirely on their ability to block respiratory enzymes (see) owing to what fabrics lose an opportunity to consume the oxygen delivered by blood. At hron. impact of HCN on an organism an important role in intoxication is played by the oppression of products of thyroid hormones a thyroid gland caused not directly HCN, and the rhodanate connections which are formed of it in an organism.

Hron. poisoning of HGN in its initial stage is characterized by decrease in the ABP, oppression of cordial activity, hurried breathing, sometimes an enlargement of the thyroid gland, change of gastric acidity, falling of the weight (weight) of a body. At the termination of contact with the toxic agent these phenomena disappear almost completely.

At expressed hron. poisoning of HCN and connections C. to. weakness, a febricula, dizziness, perspiration, bystry fatigue, an acrimony, pains in an anticardium, a heartache and extremities, tachycardia, dyspepsia are noted a headache (preferential in temporal area). Develop a neurotic syndrome (see. Neurasthenia ), a vegetoastenichesky syndrome (see. Asthenic syndrome ), vegeto-vascular dystonia (see. Neurocirculatory dystonia ), nystagmus (see), expansion of borders and deaf cardiac sounds are auskultativno defined. Hypotonia, protein in urine, decrease in concentration of glucose in blood and increase in concentration in blood milk to - you, the high content of hemoglobin are characteristic at not changed quantity of erythrocytes, an enlargement of the thyroid gland. At hron. poisoning of HCN always note painful reaction to alcohol.

The rhodanates which are formed in fabrics at hron. poisoning of HCN, breaking synthesis of thyroid hormones, promote development hypothyroidism (see).

Sometimes distinguish several forms hron. poisonings of HCN: cardiopulmonary — with the phenomena of a hypertrophy of heart, decrease in the ABP and a bronchoalveolar staz; a hematologic form — with increase in a hemoglobin content and erythrocytes, a neutropenia, mono - and a lymphocytosis; alimentary — with increase in standard metabolism and concentration of glucose in blood; gastrointestinal — with the phenomena of dyspepsia; renal — with the advent of protein in urine; skin — with mestnsh damage of skin in the form of cracks, eczemas, and also with conjunctivitis and lachrymation; nervous — with short wind, dizzinesses, an adynamy, myotonia of a stomach, trembling of extremities, sleeplessness, loss of memory and other mental disorders, to-rye in total can give a picture intoksikatsionny psychosis (see).

Acute poisoning of S. to. at high concentration of HCN in inhaled air or at its hit inside causes almost instant loss of consciousness; there comes paralysis of a respiratory center, and soon — a cardioplegia (a so-called apoplektiformny form of poisoning). At smaller concentration of poison distinguish several stages of poisoning. Initial stage: the scratching in a throat, is burning - bitter taste in a mouth, hypersalivation, numbness of lips and language, reddening of a conjunctiva, muscular weakness, difficulty of the speech, dizziness, a headache, feeling of warmth in a stomach, nausea, vomiting, desires on defecation, rush of blood to the head, heartbeat, retrosternal pains, pains in heart and in epigastriums; breath becomes frequent, then becomes deeper. If at this stage of poisoning to bring the person to fresh air, all symptoms quickly disappear. Stage of an asthma: the increasing weakness, pains in heart, rare and deep breath, an urezheniye of pulse, severe short wind, nausea, vomiting, expansion of pupils, an exophthalmos. Stage of spasms: feeling of melancholy, the amplifying asthma, a loss of consciousness, severe spasms, including chewing muscles with a bite of language. Stage of paralysis or asphyxia: full loss of sensitivity and reflexes, an involuntary urination and bowel emptying, breath becomes even more rare, superficial and wrong and at last stops.

To effects of acute intoxication of S. to. or cyanic connections the adynamy, encephalopathy, cerebral focal disturbances belong (parkinsonism, cerebellar and pyramidal syndromes, etc.).

The diagnosis of intoxication of S. to. and cyanic connections the wedge, pictures taking into account circumstances is based on features, at to-rykh there was poisoning. Diagnostic value have a smell of bitter almonds from a mouth, at intoxication of considerable degree — bright pink complexion and mucous membranes. Hron. intoxication is diagnosed generally in the presence of the nonspecific manifestations of functional disturbance of a nervous system arising at persons with a long standing of work in the conditions of contact with S. to. or with cyanic connections in the concentration exceeding maximum allowable concentration. At the same time other reasons of functional disturbances of a nervous system are excluded.

For diagnosis hron. S.'s intoxications to. the instruction in the anamnesis on the acute poisonings with cyanic connections postponed in the past in initial stages matters.

First aid and emergency treatment

It is necessary to begin antidotal therapy immediately (see. Antidotes of OV ), to stop further intake of poison, injured to take out on fresh air, to take off the contaminated clothes, to provide rest, heat. Along with antidotal therapy carry out inhalations by oxygen (optimum — hyperbaric oxygenation!), subcutaneously — 1 ml of 5% of solution of ephedrine and 2 ml of Cordiaminum. The close check behind size ABP is necessary! At hit of poison through a mouth along with antidotal therapy immediately do a gastric lavage of 0,1% by solution of potassium permanganate, 5% solution of sodium thiosulphate or 2% solution of hydrosodium carbonate; give salt laxative, plentiful drink. Intravenously repeatedly enter on 20 — 40 ml 40% of solution of glucose with thiamin (1 ml of 5% of solution) and ascorbic to - that (5 ml of 5% of solution). At a low pulse and the lowered ABP in addition intravenously enter 40 ml of 1,5% of So2-EDTA solution (dicobalt salt of ethylene diamine tetraacetate), at weak effect — repeated administration of this drug in half quantity. At disturbance or an apnoea intravenously enter 0,5 ml of 1% of solution of lobeline or 1 ml of 0,5% of solution of Cytitonum, it is long carry out an artificial respiration. After the victim recovered consciousness also its breath was recovered, immediate hospitalization is necessary.

At hron. S.'s poisoning to. symptomatic treatment.

Measures of the prevention

ensuring strict tightness of devices and the equipment Is necessary, from to-rogo HCN, and observance of measures for safety of storage of S. can be allocated to. and its salts, their transportation, on destruction and neutralization of a container according to. dignity. the rules of design, the equipment and the maintenance of warehouses for storage of strong toxic agents approved by M3 of the USSR.

On productions, in air of workrooms to-rykh HCN can be allocated, use industrial filtering is obligatory gas masks (see) at high concentration of HCN in air — the isolating gas masks. Skin shall be protected by rubber or polyvinyl chloride gloves, aprons and boots. Improvement corresponding tekhnol is important. processes with replacement of cyanic connections and S. to. on chemical substances, safe for the person, and also continuous control of air, a working zone with the automatic sound and light alarm system.

All working shall know about toxic action of HCN and cyanides and about measures of first aid by the victim. On the productions connected with receiving and S.'s use to., where there is a danger of emergence of HCN in air, once a year perform medical examinations (see. Medical examination ). Working with S. to. and other cyanic connections provide privileges.

Examination of working capacity

After the postponed acute poisonings of S. to. working capacity remains to easy degree kept, at the residual phenomena of intoxication (adynamy) is shown temporary (for 1 — 2 month) discharge from works with toxicants. At the resistant nature of disturbances of health (an adynamy, encephalopathy, etc.), including and at hron. intoxications of working transfer to disability owing to occupational disease. Due to the hypersensitivity of such patients to influence of many environmental factors work not only in contact with chemical substances, but also connected with considerable physical and nervnoemotsionalny tension, in a heat, closeness and so forth is quite often contraindicated to them.

Maximum-permissible concentration of cyanic connections in terms of hydrogen cyanide in air of a working zone makes 0,3 mg! m*.

Cyanhydric acid in the medicolegal relation

S.'s Poisonings to. and cyanic connections are rather rare. Generally they have character of accidents at careless handling of poisons in a lab. conditions or as a result of consumption of a large number of kernels of drupaceous fruits (bitter almonds, peaches, plums, apricots, sweet cherry). The absolute lethal dose for the person makes 40 g of bitter almonds or 100 cleared seeds of the apricots containing 1 g of dl-mandelonitrile gentiobioside — the alkaloid which is easily hydrolyzed on S. to., glucose and oil of bitter almonds. Isolated cases of suicide and murder by means of potassium cyanide meet. The conclusion about poisoning as to a cause of death is based on set a wedge, manifestations and results court. - medical and a lab. methods of a research. At a fulminant (apoplektiformny) form of poisoning of S. to. death comes in 3 — 5 min., at slowed down a little later.

At survey and necropsy note characteristic cerise color of livors mortis, auricles, lips, faces, a smell of bitter almonds from internals, red color of fabrics and internals, swelling of a mucous membrane of a stomach. At poisoning with kernels of drupaceous fruits in a stomach find undigested particles of these kernels — white grains and brown scales of a cover.

Court. - subject to a chemical research a stomach with contents, a brain, a liver, a kidney, blood and urine. Page to. isolate from acidified biol. material by distillation. Its high-quality detection is based on reaction of formation of Prussian blue, quantitative — on definition with solution of caustic silver or a fotokolorimetrirovaniya (see. Colorimetry ). At a spectral blood analysis the range of a tsiangemoglobin comes to light. At suspicion of poisoning with tsiansoderzhashchy kernels of drupaceous fruits conduct a botanical research of contents of a stomach and intestines.



Bibliography: Avdeev M. I. Forensic medical examination of a corpse, page 371, M., 1976; Bobkov S. S. and About m and the district about in S. K. Cyanhydric acid, M., 1970; Harmful substances in the industry, under the editorship of N. V. Lazarev and I. D. Gadaskina, t. 3, page 260, L., 1977; Treatment of acute poisonings, under the editorship of M. L. Tarakhovsky, page 179, Kiev, 1982; L at N and to about in E. A. Clinical toxicology, page 189, M., 1982; Occupational diseases, under the editorship of A. A. Letavet, etc., M., 1973; The Guide to forensic medical examination of poisonings, under the editorship of R. V. Berezhny, etc. „page 141, M., 1980; The Reference book on professional pathology, under the editorship of L. N. Gratsianskaya and V. E. Kovshilo, page 341, L., 1981; Shvaykova M. D. Toxicological chemistry, page 69, M., 1975.


L. E. Milkov (gigabyte.), A. I. Tochilkiv (chemical), K. I. Hizhnyakova (court.).

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