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XYLOLS (dimethylbenzenes) — aromatic hydrocarbons, homologs of benzene, in a ring to-rogo two hydrogen atoms are replaced on methyl radicals; With 6 H 4 (CH 3 ) 2  ; cause irritation and oppression of function of the hemopoietic bodies, show the narcotic action similar to effect of benzene and toluene. To. are widely used in gistol. to the equipment, paint-and-varnish and coke-chemical industry, etc.

To. exist in the form of three isomers: orto-, meta - and para-xylols; t ° Kip mixes of isomers apprx. 140,5 °, density 0,867 — 0,869; water solubility of 0,013% (at 22 °). All isomers K. mix up with alcohol, ether, acetone, chloroform, benzene. To. burns and forms explosive mixes with air in the range of concentration of 3,0 — 7,6%; self-ignition temperature 553 °, temperature of flash 29 °. Pier. weight (weight) 106,17. To. receive from oil or from so-called light benzene during the coking of coal.

At concentration To. in air of 0,87 mg/l within 3 — 5 min. the irritation of a mucous membrane of eyes, a nose and throat appears.

At acute poisonings To. there is dizziness, heartbeat, feeling of intoxication, numbness of hands and legs, a fever, an asthma, nausea, vomiting are possible; in hard cases a loss of consciousness, at return of consciousness — excitement, headaches, stomach aches, sleeplessness, feeling of crawling of goosebumps.

At chronic poisonings To. the headache, fatigue, drowsiness, the general weakness, a sonitus, dizziness, cardiovascular frustration, lack of appetite, nausea, sometimes vomiting, pressure sense in a stomach, conjunctivitis, nasal bleedings, an inflammation of a nasopharynx is noted. From blood: often the anemia which is followed by a poikilocytosis and an anisocytosis, a leukopenia, sometimes a leukocytosis with a relative lymphocytosis, unsharp thrombocytopenia or bleeding without decrease in number of thrombocytes.

In urine protein, urobilin, urobilinigen sometimes is found (see. Urobilinuria ).

At long contact with To. at a part working, neglecting precautionary measures, the neurotic syndrome and a neurangiosis can develop, women have frustration of a menstrual cycle. Cases of a serious poisoning are described To. pregnant women.

Irritant action of a n-xylol is one skin stronger, than action of the m xylol, apprx. 25% applied on the unimpaired skin of a xylol is soaked up in 5 — 10 min.

At poisoning To. find in all bodies, especially in adrenal glands, marrow, a spleen, nervous tissue.

As a result of oxidation of one methyl group all isomers K. turn in corresponding methyl-benzoic to - you. au-Toluilovaya to - that conjugates generally with glucuronic to - that, and m - and n-methyl-benzoic to - you — with glycine, forming methylbenzaminoacetic to - you. At the person of 72% of m xylol turns in methylbenzaminoacetic to - that. All metabolites To. are excreted with urine.

First aid at poisoning. In hard cases at sharp weakening or dead stop of breath it is necessary to start immediately an artificial respiration by method of companies in a mouth. Intravenously (slowly) enter Bemegridum (2 — 5 ml of 0,5% of solution), etimizol (0,1 g), lobeline (1 ml of 1% of solution). Adrenaline and adrenomimetichesky drugs are contraindicated! Injured urgently hospitalize.

Individual protection consists in use of the filtering gas mask of brand A. Time of its protective action from vapors K. at concentration of 0,5 mg/l makes 13 — 14 hours, at 1 mg/l — apprx. 6 hours, at 2 mg/l — 3,5 hours, at 3 mg/l — 2,3 hours and at 5 mg/l — 1 hour 15 min. Time of protective action of a gas mask of brand A with the filter is twice shorter. At high concentration of vapors K. use the hose isolating gas masks with forced feed of air (see. Gas masks ).

Observance of measures of personal hygiene, use of protective creams, ointments and pastes is necessary.

Measures of the prevention it is poisoned and y To. provide appropriate sealing of processes and ventilation at the enterprises koksokhy. industries.

Maximum allowable concentration To. makes 50 mg/m 3 .

For definition To. in air at their concentration of 0,5 — 2 mg/l the universal gas analyzer of U G-2 with an indicator tube or a gas analyzer of Gamma-1 is suitable.

A qualitative method of definition To. it is based that nitrate K. the diluted nitrosulphuric acid forms with alkali in the radio and alcohol environment the connection painted in blue-green color.

Xylols in the histologic equipment. To. well dissolve paraffin, Canada balsam, polystyrene etc. therefore they are applied in gistol, the equipment as intermediate agent during the work with the called substances. To. easily get into fabrics, forcing out from them alcohol and clarifying them, but at long influence To. fabrics become brittle.

For paraffin embedding the dehydrated pieces of fabric keep in mix of absolute alcohol and To. (1:1), in pure To., mixes K. with paraffin, and then immerse in the melted paraffin. The paraffin sections pasted on glasses exempt from paraffin, placing glasses in K. Okrashennye and carry out the cuts dehydrated in alcohols of the ascending fortress through karbol — a xylol (1 part crystal carbolic to - you on 3 parts K.) or other environments, clarify them in pure To. also conclude in solution of Canada balsam or one of its substitutes or in solution of polystyrene in neutral To.

See also Benzene .

Bibliography: Harmful substances in the industry, under the editorship of N. V. Lazarev and E. N. Levina, t. 1, page 106, L., 1976, bibliogr.; Merkulov G. A. Course of the patologogistologichesky equipment, page 54, etc., L., 1969; H e of N and c of e with to at K. D. Organic chemistry’ the lane from Romanians., t. 1, page 323, etc., M., 1962; E. A rebuzzing. Sanitary and chemical control of the air environment, page 24, etc., L., 1978; P about with to and G. I. N and L of e in and nanosecond about N L. B. Mikroskopicheskaya of the technician, page 135, etc., M., 1957.

G. Ya. Vidershayn; Ya. E. Hesin (gist.).