Manganese

Manganese, chemical element, symbol Mn; atomic number 25; atomic weight 54.93; metal of group 7 of the periodic system of elements. From natural compounds are known the minerals pyrolusite MnO₂, hausmannite Mn₃O₄, braunite Mn₂O₃, manganite Mn₂O₃·H₂O, manganese spar MnCO₃, silicic acid Mn (rhodonite, pink stone). Manganese ores in the USSR are found in the Caucasus, Urals, and lower reaches of the Dnieper. Manganese metal is grayish in color, very hard, melting point 1,260°. specific weight 7.4, soluble in acids. Technical use is made of Mn alloys: with iron - mirror cast iron (5-15% Mn), ferromanganese (70-80% Mn), used in the production of manganese steel, possessing exceptional hardness; with copper and nickel - manganin (84% Cu, 4% Ni, 12% Mn), which does not change its electrical conductivity with temperature change. Mn forms a series of oxides: 1) MnO, 2) Mn₂O₃, 3) Mn₃O₄, 4) MnO₂, 5) manganic anhydride MnO₃, 6) manganese anhydride Mn₂O₇. Salts of manganese acid easily release part of their oxygen, and therefore are strong oxidizing agents. To detect Mn, dry soda and saltpeter are added to the substance being tested and calcined on a platinum spatula; a blue-green alloy is obtained. The reaction is very sensitive. Mn is a component of the ash of most plants. "It is found in the blood and organs of mammals, birds, fish (Bertrand and Medigreceanu), in the blood of sea feathers and in the tissues of freshwater shells Unio and Anadonta, as well as in the cases and tissues of marine annelids. In humans, it is found in traces in blood serum, bile, and gallstones. Mn, along with iron, has important significance in soil life. Its salts significantly affect soil fertility. Due to the ability of a number of bacteria to deposit Mn along with iron, the cycle of Mn in the soil layer is carried out. In higher animals, Mn is a companion of iron, and in lower animals it physiologically replaces it. Bertrand considers that the action of oxidative enzymes depends on the presence of Mn in them. Mn salts promote the decomposition of hydrogen peroxide - Mn ions are antagonists of Na ions. The therapeutic use of Mn salts is based on their oxidizing ability. The greatest use is made of potassium permanganate as a disinfectant, deodorizing, and cauterizing agent.

N. Tolchevskaya. The physiological action of Mn compounds, like other heavy metals, manifests itself mainly on the intestine, central nervous system, and kidneys. Mn salts are absorbed by the gastrointestinal tract in very small amounts, and after being absorbed in the small intestine, they are excreted in the large intestine, with only a small amount of Mn retained in the body, mainly in the spleen, liver, and intestinal wall. Mn has an irritating effect on the gastric and small intestinal mucosa, but in general its compounds when administered per os are little toxic. The resorptive action of Mn is found in experimental poisoning of animals by administering its double salts subcutaneously or intravenously. With a large toxic dose, e.g. 14 mg MnO per 1 kg of weight and above, epileptiform convulsions appear in warm-blooded animals, which soon end in death. With the minimum lethal dose, poisoning symptoms in animals develop gradually; at this time diarrhea, general weakness, decreased reflexes, paralysis of the extremities, decrease in body temperature are observed, then paralysis phenomena follow, leading to cessation of breathing with the heart still working. In the urine of animals in the early stage of poisoning, bile pigments can be detected, later albuminuria develops. The phenomena of nephritis are even more strongly expressed in chronic poisoning of animals, which occurs with prolonged subcutaneous administration of small doses of Mn salts; in this case, the inflammatory process first affects the cells of the tubule epithelium, and then the interstitial tissue. Mn administered parenterally is excreted mainly through the intestine and to a lesser extent through the kidneys. In humans, cases of chronic Mn poisoning are observed mainly among workers in mills grinding manganese ores, and in the chemical industry in the production of manganese preparations, where workers constantly inhale manganese dust. Symptoms of poisoning - see below. In view of the similarity of Mn with iron in chemical properties and physiological action, it was tried for the treatment of chlorosis, however, these attempts were unsuccessful. At present, for this purpose, compounds of iron and Mn are sometimes used, e.g. Liq. Ferri peptonati cum Mangano. The greatest therapeutic significance is attached to Mn preparations that have mainly a disinfecting action due to their ability to easily release oxygen in an active form. Preparations. 1. Kalium hypermanganicum (permanganicum, supermanganicum, oxymanganicum) (Kalium permanganate), potassium salt, chameleon (KMnO₄), FUM - prismatic crystals of dark violet color, fairly soluble in water (1:16). It has an antiseptic action due to the fact that, coming into contact with organic substances, it oxidizes them, while itself is reduced, losing its antiseptic properties. For this reason, the antiseptic action of permanganate is limited to the surface layer of the skin or mucous membranes. The oxidizing action of permanganate also determines its deodorizing property, as well as its cauterizing action on mucous membranes: even a 1% solution of it has a cauterizing effect, weaker solutions have an astringent and at the same time antiseptic and deodorizing action. Potassium salt is also recommended as an antidote in poisoning by phosphorus, cyanates, morphine and other alkaloids, which it oxidizes, converting them into less toxic compounds. However, such an action it can have when administered per os only when the poison is still in the stomach and can be oxidized by permanganate before the latter decomposes, while the introduction of a solution directly into the blood to neutralize the absorbed poison is by no means safe. Potassium salt is used externally - 0.25% solution for rinsing the mouth and throat, 0.1-0.25% for douching in gonorrhea, 5% for limited application to burns, 5-10% as a hemostatic agent; in the form of enemas in dysentery - 0.5 : 1,000; in the form of a 4% powder - for bromidrosis of the feet. Internally 0.05-0.1 in pills with Bolus alba, 3-5 times a day in dys- and amenorrhea. In bites of poisonous snakes, a 1% solution is injected into the bite area. KMnO₄ solutions should be kept in orange glass bottles with glass stoppers. In acute poisoning with potassium permanganate, the mucous membranes of the digestive tract are affected, mainly the stomach; in such poisonings, first aid measures are: washing the stomach, preferably with a water emulsion of protein, administering the latter internally, as well as a 2% solution of hydrogen peroxide, slightly acidified with acetic acid, to decompose the permanganate. 2. Manganum carbonicum oxydulatum, manganese carbonate (MnCO₃), a pinkish-white powder, almost insoluble in water, soluble in diluted acids; given internally with iron preparations in chlorosis and as an emmenagogum in doses of 0.1-0.5 per dose in pills (an inappropriate means). 3. Manganum chloratum (MnCl₂ · 4H₂O), manganese chloride, deliquescent crystals of pink color, easily soluble in water (1:2), bitter and astringent taste; externally 1-5% solution for rinsing the mouth and pharynx as an astringent and partly antiseptic. 4. Manganum sulfuricum (MnSO₄ · 4H₂O), manganese sulfate, crystals of pale pink color, easily soluble in water, insoluble in alcohol; internally - as the carbonate salt, externally - in the form of ointment for various skin diseases. 5. Calcium permanganicum, potassium calcium salt, crystals of dark violet color, easily soluble in water; used as potassium salt. 6. Zincum permanganicum, zinc permanganate, dark red, almost black crystals, easily soluble in water; externally for douching in urethritis, especially acute, in the form of a solution 1:4,000.

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M. Likhachev. Prof. harmfulness. M. is obtained from manganese ores, which are mined in Brazil, Japan, Germany; in the USSR, the mining of manganese ore on a large scale is concentrated in Chiatura (Georgia). In industry, M. is used to obtain various manganese compounds (in particular potassium permanganate), for obtaining chlorine [by the Weldon method], for coloring glass, producing paints, varnishes, enamels, for preparing special grades of iron and steel, etc. The danger to workers is represented by fine manganese dust, which is released in a number of processes; when working in mines (in Chiatura 15-30 mg of dust per 1 m³ of air was found), during grinding of ore, drying, separation of M. _;in the ore from other metals by means of electromagnets, etc., dust enters the body through the respiratory tract or gastrointestinal tract; it is excreted from the body mainly through the intestine (Handovsky and others), less through the kidneys; M. is deposited in the bones. (The result of prolonged inhalation of M. dust is damage to the respiratory tract and chronic poisoning. Reports of manganosis in Chiatura miners exist by Bakradze, who from autopsy protocols (even before the war) provides characteristic excerpts: "Lungs affected by manganosis became so hard that they could be freely taken out of the body and placed on the table as a solid object; they felt like a solid object to the touch; upon histological examination, all tissues and cells of the lungs were impregnated with manganese dust". Among the causes of morbidity and mortality, pneumonia stands in first place, which gave (in 1906-1911) 28-40% of the total morbidity; mortality from lobar pneumonia was 4 times higher than mortality from all other diseases. Acute M. poisonings have not yet been observed anywhere. Chronic poisonings were first described by Cooper in 1837, then in 1901 Jaksch and Embden again drew attention to this disease, presented a number of cases and gave a detailed description of the clinical picture of the disease. Later, reports of poisoning cases began to appear more frequently, and at present there are data on approximately 50 cases (in Europe and the USA; detailed summary by A. Hamilton). The symptoms of poisoning develop very slowly. In pronounced cases, the following symptoms are noted: lethargy, stupor, mask-like face, monotonous speech, forced laughter and crying, mental disorders, retropulsion and propulsion, tremor, increased muscle tone; in a number of cases (Jaksch) weakness in the lower extremities, difficulty walking, a peculiar "cock" gait, pathological reflexes of Babinski, Oppenheim; sometimes disorders of sensitivity are observed in the absence of pain, etc. Changes in the liver, in the blood-increase in the number of red blood cells (Schwarz), etc. have also been described. Autopsies of persons who died from M poisoning, as well as experiments on monkeys, showed that there are degenerative changes in the brain and spinal cord; they are especially sharply expressed in the corpus striatum (globus pallidus, putamen, nucleus caudatus), which explains the clinical similarity of chronic manganese poisoning with Wilson's disease or with parkinsonism. Experimentally, some authors managed to obtain similar selective anatomical changes; however, other authors obtained more diffuse pictures. The disease symptoms caused by M. are persistent - after leaving production, improvement, if it occurs, is only partial (Jaksch).-Prevention: mechanization and sealing of processes associated with dust release (especially - grinding); rotation of workers (periodic transfer to work not related to M processing). - Treatment: removal from work, electrization, sulfur baths, enhanced nutrition, etc.

N. Rosenbaum. Discovery in legal cases. Only potassium permanganate in the amount of several grams can act as a poison. Smaller amounts, as well as salts of manganous oxide and its peroxide, are no longer poisons. Potassium permanganate in the body is reduced to salts of manganous oxide and oxides of manganese. The discovery of potassium permanganate as such can occur in exceptional cases, for example in vomit, in the remains of the "poison". In view of the above, the toxicological significance lies in finding large amounts of M. in the internal organs, which in connection with the circumstances of the case can make it possible to judge the presence of poisoning with permanganates (potassium permanganate). To discover M., the liquid after destruction of organic substances (see Poisons, isolation) is precipitated with hydrogen sulfide in an acidic solution, then after adding ammonia until an alkaline reaction, H₂S again. The precipitate of sulfides from the alkaline solution is dissolved in nitric acid, evaporated to dryness. The residue is dissolved in water, an excess of ammonium chloride is added, precipitated with aqueous ammonia and filtered. The colorless filtrate turns brown on standing, precipitation of brown oxides of manganese occurs. The filtrate is acidified with acetic acid, hydrogen sulfide is passed to precipitate zinc (if present), it is made alkaline with ammonia and again saturated with hydrogen sulfide: if M. is present, a meat-red precipitate is obtained. For quantitative determination, the manganese sulfide is transferred to a weighed porcelain crucible, calcined, the residue is moistened with sulfurous acid solution, dissolved in the smallest possible amount of concentrated sulfuric acid, the excess acid is carefully removed by heating, and the crucible is heated in an air bath until the residue reaches constant weight (MnSO₄).