From Big Medical Encyclopedia

HYDROCHLORIC ACID (Acidum hydrochloricum) — strong monobasic acid, solution of HCl hydrogen chloride in water, is one of the most important components of a gastric juice; in medicine it is used as medicine at insufficiency of secretory function of a stomach. Page to. is one of the most usable chemical reactants used in biochemical sanitary and hygienic and clinical diagnostic laboratories. In stomatology of 10% solution C. to. apply to whitening of teeth at a fluorosis (see Whitening of teeth). Page to. use for receiving alcohol, glucose, sugar, organic dyes, chlorides, gelatin and glue, in pharm. the industries, at a tanning and coloring of skin, saponification of fats, by production of active coal, dyeing of fabrics, etching and soldering of metals, in hydrometallurgical processes for cleaning of boreholes of deposits of carbonates, oxides and other rainfall, in a galvanoplasty, etc.

S. to. for the people contacting to it in a process of manufacture represents considerable professional harm.

Page to. it was known in 15 century. Its opening is attributed it. to the alchemist Valentin. Long time was considered that S. to. the muriya is oxygen connection of a hypothetical chemical element (one of its names from here — acidum muriaticum). Chemical structure of S. to. it was finalized only in the first half of 19 century by Davy (N. Davy) and Ge. Gay-Lussac.

In the nature free S. to. practically does not meet, however its salts sodium chloride (see. Sodium chloride), potassium chloride (see), magnesium chloride (see), Calcium chloratum (see), etc. is spread very widely.

HCl hydrogen chloride at usual conditions represents colorless gas with specific pungent odor; at allocation in a humid air it strongly «smokes», forming the smallest droplets of an aerosol of S. to. Hydrogen chloride is toxic. The weight (weight) is 1 l of gas at 0 ° and 760 mm of mercury. it is equal to 1,6391 g, density by air 1,268. Liquid hydrogen chloride boils at — 84,8 ° (760 mm of mercury.) also hardens at — 114,2 °. In water hydrogen chloride is well dissolved with calorification and S.'s education to.; its solubility in water (/100 of H20): 82,3 (0 °), 72,1 (20 °), 67,3 (30 °), 63,3 (40 °), 59,6 (50 °), 56,1 (60 °).

Page to. represents colorless transparent liquid with pungent odor of hydrogen chloride; impurity of iron, chlorine or other substances paint S. to. in yellowish-greenish color.

Approximate value of concentration of S. to. as a percentage it is possible to find if ud. S.'s weight to. to reduce by unit and to increase the received number on 200; e.g., if ud. S.'s weight to. 1,1341, its concentration is equal to 26,8%, i.e. (1,1341 — 1) • 200.

To page to. it is chemically very active. It dissolves with a hydrogen release all metals having negative normal potential (see Potentials physical and chemical), transfers many oxides and metal hydroxides to chlorides and allocates free to - you from such salts as phosphates, silicates, borates etc.

In mix with nitric to - that (3:1), so-called aqua regia, S. to. reacts with gold, platinum and other chemically inert metals, forming complex ions (Ais14, PtCl6, etc.). Under the influence of S.'s oxidizers to. is oxidized to chlorine (see).

Page to. reacts with many organic matters, napr, proteins, carbohydrates, etc. Nek-ry arylamines, natural and synthetic alkaloids and other organic compounds of the main character with S. to. form salts — hydrochlorides. Paper, cotton, flax and many synthetic fibers under the influence of S. to. collapse.

The main way of receiving hydrogen chloride — synthesis from chlorine and hydrogen. Synthesis of hydrogen chloride proceeds according to reaction of H2 + 2С1-^2HCl + 44,126 kcal. Other ways of receiving hydrogen chloride are chlorination of organic compounds, dehydrochlorination of organic chlorderivatives and hydrolysis of nek-ry inorganic compounds with dehydrochlorination. More rare, in a lab. to practice, apply an old way of receiving hydrogen chloride interaction of sodium chloride with a chamois to - that.

Characteristic reaction to S. to. and its salts formation of a white curd of AgCl silver chloride, soluble a lot of water solution of ammonia is:

HCl + AgN03 — AgCl + HN03; AgCl + 2NH4OH - [Ag (NHs)2] of Cl + + 2H20.

Store S. to. in glasswares with ground stoppers in the cool room.

In 1897 by I. P. Pavlov it was established that obkladochny cells of gastric glands of the person and other mammals cosecrete S. to. constant concentration. Assume that the mechanism of secretion of S. to. the gastric juice consists in transfer of ions of H+ a specific carrier on an exterior surface of an apical membrane of intracellular tubules of obkladochny cells and in their receipt after additional turning into (see). Ions of C1 ~ from blood get in about - a masonry cell at simultaneous transfer of an ion of sales tax bicarbonate in an opposite direction. Thanks to it ions of C1 ~ come to an obkladochny cell against a gradient of concentration and from it — to a gastric juice. Obkladochny cells cosecrete

solution C. to., concentration to-rogo makes apprx. 160 mmol!

hp to. plays an important role in digestion (see): it creates conditions for autocatalytic activation of the proferments emitted with gastric glands and causes the necessary size pH of the environment for action gastric peptide-hydrolases (see). Denaturing to a certain extent proteins of food,

S. to. makes them more available for proteolysis; it causes bactericidal properties of a gastric juice, slows down release of gastrin (see), participates in reflex regulation of function of a pyloric press. Coming to intestines (see) S. to. is the main incentive for release secretin (see), exciting secretory activity of a pancreas (see) both a liver (see), and nek-ry other hormones.

Quantitative assessment of maintenance of S. to. in a gastric juice consists in definition of the total (total) acid, i.e. in determination of content of all acid components of a gastric juice, by titration by alkali (Mikhae-lisa method), the free (dissociated) S. to. and S. to., connected with proteins (Tepfer's method). Total acid of a gastric juice can reach 0,58% of S. to., free S.'s maintenance to. — 0,50%. The connected S.'s number to. determine by a difference between total acid and free S.'s maintenance to. For diagnosing of nek-ry went. - kish. diseases also determination of number

of S. is of great importance to., developed in unit of time, a so-called output - hour.

Believe that 90% of HCl getting to an organism with inhaled air are adsorbed by mucous membranes of upper respiratory tracts. At contact with fabrics exogenous S. to. it is quickly neutralized.

Hydrochloric acid as professional harm

possesses Harmful action S.'s aerosol to., airborne a working zone; besides, during the work with S. to. it is necessary to consider a possibility of education in air of other toxic connections, napr, AsH3 hydrogen arsenide (see Arsenic).

At high concentration of hydrogen chloride in air of production rooms note irritation of mucous membranes of respiratory tracts with cold, cough up to suffocation, in a phlegm blood can sometimes appear; conjunctivitis, opacification of a cornea are possible. Hron. influence of an aerosol of S. to. can lead to development of hypertrophic and atrophic rhinitises (see), sometimes with ulcerations of a mucous membrane of a nose up to a perforation of a nasal partition, tracheitises (see), bronchitis (see), to destruction of teeth, went. - kish. to frustration; inflammatory diseases of skin are possible.

S.'s aerosol to. causes a sharp dermatalgia of the person. Burns hydrochloric acid are not so heavy as burns nitric acid (see) and sulphuric acid (see). The acute prof. of poisoning called by inhalation of an aerosol of S. to., meet extremely seldom. A wedge, a picture of acute poisoning with S.'s aerosol to. it is characterized by cough, heavy hurried breathing; in lungs small-bubbling rattles are heard, the phlegm is expectorated with great difficulty, hypostasis of a throat and phonatory bands is possible; weakness, skin hot and dry, earthy color, acute pains in a stomach, frequent vomiting yellowish slime. At S.'s hit to. inside the wedge, a picture of poisoning develops (see): severe pains in a gullet and a stomach, hypersalivation, pernicious vomiting of a temngma the masses containing nekrotizirovanny elements of a mucous membrane of a stomach, motive excitement, spasms, pallor or cyanosis of the person, pulse weak, frequent, arrhythmic; the collapse is possible. Death comes during the first hours and even minutes from shock or asphyxia owing to hypostasis of a throat, is more rare — in several days from diffuse peritonitis if there was a perforation of the stomach, or other complications (bronkhopnevmoniya, a nephrosonephritis, etc.).

First aid and emergency treatment

At inhalation poisonings of S. to. the victim needs to be taken out immediately on fresh air, to give inhalation of oxygen. A throat it is necessary to rinse 2% solution of hydrosodium carbonate, the same solution to wash out eyes and a nose. At difficulty of breath dig in on 4 — 5 drops 2 — 3% of solution of ephedrine in a nose 3 — 4 times a day, subcutaneously enter 1 ml of 0,1% of solution of atropine. In hard cases at poisonings with an aerosol of S. to. to prevention and treatment of pneumonia apply aerosol inhalations of antibiotics, appoint a course of treatment antibiotics and streptocides.

At S.'s hit to. high concentration on skin needs to wash immediately skin water within 5 — 10 min. (better than 2 — 4% solution of hydrosodium carbonate); further treatment — symptomatic (see Burns).

At damage of eyes after washing by solution of hydrosodium carbonate in eyes dig in on 1 drop 2% of solution of novocaine or 0,5% of solution of Dicainum with adrenaline (1:1 000), then in a conjunctival sac put sterile liquid or peach-kernel oil. In the subsequent treatment consists in an instillation in eyes of 30% of solution of albucid, use of a hydrocortisone oculentum.

At peroral poisonings it is necessary to wash out urgently a stomach via the probe water and then to carry out a symptomatic treatment (see Poisonings).

Examination of working capacity

At moderately expressed and for the first time diagnosed acute and hron. professional poisonings of S. to. treatment is appointed, the diseased is exempted from work, or temporarily transferred to other work. During the progressing a wedge, symptoms of poisoning the diseased is discharged of work with substance and is subject to rational employment.

Measures of the prevention. Individual protection from intoxication consists in carrying in production rooms, air to-rykh contains S.'s aerosol to. in concentration, above admissible, a gas mask of brand B (see Gas masks), protective tight points (see), overalls from acidproof cloth, mittens, gloves (see. Clothes special ) and a boot (see Footwear, production) from antacid rubber. Full sealing of tanks is necessary for storage and S.'s transportation to., and also mechanization of all productions on S.'s receiving to., its plum and filling of a container. Production rooms shall be equipped with positive-pressure ventilation (see), fountainlets and hydrants for immediate washing off of splashes of the acid which got on skin or into eyes. Medical examinations are obligatory preliminary and periodic (once in 2 years) (see. Medical examination) and surveys by the stomatologist once in 6 months all working in contact with hydrogen chloride or S. to.

Maximum allowable concentration of an aerosol of hydrochloric acid in air of a working zone of 5 mg/m3.

Hydrochloric acid in the medicolegal relation

Poisoning with hydrochloric acid comes at its peroral introduction (a lethal dose of 10 — 15 g) with the suicide purpose or as a result of accident.

At a research of a corpse around a mouth and on a neck characteristic signs of a chemical burn in the form of dense brown-gray spots or potek clearly are visible. The mucous membrane of an oral cavity, a throat and a gullet is condensed, with sites of a coagulative necrosis. In a stomach dark-brown liquid of highly acid reaction with particles of a sawn-off mucous membrane. Inner surface of a stomach dark-brown, dense; folds its dry, fragile, are maleficiated. Such changes can be also in a small bowel at the long (more than a day) course of intoxication. At intravital perforation of a stomach existence of the reactive phenomena from a peritoneum is characteristic and contents of a stomach in an abdominal cavity; at posthumous perforation of a stomach its contents remain near the place of a perforation, edge of an opening in both cases uneven. After S.'s death to. the zhe.ludka and without its perforation can diffuse through a wall, changing adjacent sites of a serous cover, a liver, spleen, kidneys. At the long course of intoxication, except local changes, find also a plethora of internals, fatty dystrophy of parenchymatous bodies; they are increased in sizes, are flabby, pale yellow color.

At gistol. a research reveal a necrosis of walls of a gullet, stomach, it is frequent also a duodenum with leukocytic and lymphocytic infiltration, hemorrhages in superficial and submucosal layers, fatty dystrophy of heart, liver, kidneys, swelling and the centers of a necrosis of tissue of liver, muddy swelling of an epithelium of gyrose tubules of kidneys.

At court. - chemical definition of S. to. fabrics of a corpse homogenize in water, dialyze homogenate also against water. In dialyzate determine an ion of C1“ by qualitative test with silver nitrate; previously dialyzate is acidified nitric to - that. As a result of reaction the characteristic white curd of AgCl silver chloride, soluble in ammonia is formed. Dialyzate is subjected by distillations and again determine existence of an ion of C1“ by the described reaction. Quantitative definition of S. to. carry out in the distillate received as a result of distillation of dialyzate, titration by solution of alkali in the presence of methyl orange.

Court. - the medical conclusion about poisoning with hydrochloric acid as to a cause of death is based on set of results court. - medical researches of a corpse, judicial chemical go and judicial and histologic researches.

Use in medicine

In the medical practician S. to. according to GFH it is applied under the name «Acidum hydrochloricum».

Acidum hydrochloricum (Acidum hydrochloricum, synonym hydrochloric acid; GFH, joint venture. B) — colorless transparent volatile liquid with a peculiar smell and acid taste; density 1,122 — 1,124. Outwardly use 6% solution to - you itch, hydrochloric for treatment, (see) by Demyanovich's method. Apply to intake only to - that hydrochloric divorced (Acidum hydrochloricum dilutum; GFH, joint venture. B), edges supports 1 h to - you hydrochloric and 2 h water. The maintenance of HCl in it 8,2 — 8,4%, density 1,038 — 1,039.

K-that hydrochloric divorced is used for replacement therapy at various diseases. So, at insufficient secretory function of a stomach it is applied for the purpose of creation of optimal conditions to effect of gastric proteolytic enzymes, and also to improvement of regulation of transition of contents of a stomach to a duodenum. At hit in a duodenum to - that hydrochloric divorced stimulates release of secretin, to-ry promotes release of juice of a pancreas. However in average therapeutic doses to - that hydrochloric divorced at reception it with food does not allow to create optimal conditions (pH apprx. 2,0) for effect of pepsin (see) at patients with the expressed insufficiency of gastric glands. Besides, at such patients the mechanism of arousing secretory activity of a pancreas in response to hit to - you hydrochloric in a duodenum is weakened. Therefore to - that hydrochloric divorced should be combined with other means of replacement therapy at insufficiency of gastric glands and a pancreas.

At dekompensirovanny forms hron. atrophic gastritis with secretory insufficiency (an akhiliya, an achlorhydria), sometimes for improvement of appetite at the exhausted and weakened patients suffering from an achlorhydria and also at iron deficiency anemias to - that hydrochloric divorced is appointed together with iron preparations for improvement of their absorption and assimilation in an organism.

Divorced Acidum hydrochloricum, it is frequent together with pepsin, for the purpose of replacement therapy appoint inside the adult on 10 — 15 drops on 1/4 — 1/2 glasses of water 2 — 4 times a day during food (recommend to drink this solution through a straw or a polyethylene tubule in order to avoid destroying S.'s action to. on teeth); children till 1 year are given on 1 drop, from 2 to 5 years — 2 — 5 drops, from 6 to 12 years — on 5 — 10 drops on reception. The highest doses for adults inside: one-time 2 ml (40 drops), daily 6 ml (120 drops).

A contraindication to use to - you hydrochloric divorced are the peptic ulcer of a stomach and duodenum, symptomatic or medicamentous round ulcers of a stomach, erosive and erosive and ulcer gastritis, a round ulcer of a gullet, a reflux esophagitis.

Form of release: in bottles on 80 ml.

Store in bottles with ground stoppers.

See also Acids and bases .

Bibliography: Volfkovich S. I., Egorov A. P. and Epstein D. A. General chemical technology, t. 1, page 491, etc., M. — L., 1952; Harmful substances in the industry, under the editorship of N. V. Lazarev and I. D. Gadaskina, t. 3, page 41, L., 1977; Nekrasov B. V. Fundamentals of the general chemistry, t. 1 — 2, M., 1973; Acute management at acute poisonings, the Reference book on toxicology, under the editorship of S. N. Golikov, page 197, M., 1977; Fundamentals of forensic medicine, under the editorship of N. V. Popov, page 380, M. — L., 1938; Radbil O. S. Pharmacological bases of treatment of diseases of digestive organs, page 232, M., 1976; Ram and G. Kurs of inorganic chemistry, the lane with it., t. 1, page 844, M., 1963; The Guide to forensic medical examination of poisonings, under the editorship of R. V. Berezhny, etc., page 63, M., 1980.

N. G. Budkovskaya; N. V. Korobov (pharm.), A. F. Rubtsov (court.).