Aromatic hydrocarbons

Aromatic hydrocarbons are organic substances characterized by the presence in their molecule benzene ring - cyclic groups of six atoms of carbon with three double bonds. Among the aromatic hydrocarbons belong benzene and its derivatives (the toluene, xylene and other), naphthalene and its derivatives and other
Benzene aromatic hydrocarbons, mainly liquid, part of a solid body with characteristic aromatic odour. Are used as solventsand as a source products in obtaining plastics, dyes, and other Pairs of them in high concentrations have drug and partly convulsive effect.
Acute poisoning observed headache, nausea, vomiting, agitation, like alcohol, then gradually depression, rarely convulsions; death occurs from respiratory arrest. For chronic poisoning characterized by severe blood and blood-forming organs, accompanied by a decrease in blood erythrocytes, leukocytes and platelets, disorders of the nervous system, liver and endocrine organs. The most severe chronic poisoning causes benzene (see). When the effects of fumes or dust aromatic hydrocarbons there is a clouding of the lens. Irritant effect benzene derivatives on the skin increases with the number of methyl groups, especially expressed it at mesitilene (trimethylbenzene). Substitution of hydrogen in the side chain on halogen (chlorine, bromine) enhances the irritant effect of aromatic hydrocarbons on the respiratory tract and mucous membranes of eyes. The toxic properties of aromatic amino - and nitro compounds (see) are related to their ability to turn the oxygenated hemoglobin into methemoglobin.
Naphthalene and its derivatives can cause damage to the nervous system, gastrointestinal tract, kidneys, irritation of the upper respiratory tract and skin. Connections polynuclear aromatic hydrocarbons with condensed rings inherent carcinogenic activity. Tumors usually occur in direct contact with these aromatic hydrocarbons, but occasionally and in distant organs (bladder).
Treatment of poisoning. In mild cases of acute poisoning aromatic hydrocarbons must remove person from the production environment, treatment is not usually required (in the event of excitation appoint bromides, Valerian drops, it is recommended peace). In severe cases, while easing breathing resort to artificial respiration; the victim give breathing oxygen or Carbogen. Disorders of blood circulation - 10% solution caffeine-benzoate sodium under the skin and caffeine inside together with acetylsalicylic acid or amidopirinom. Epinephrine is contraindicated. Vomiting - intravenous injection of 20 ml of 40% solution of glucose. The irritation of the mucous membranes - sodium inhalation, rinsing the 2% solution of baking soda. When expressed changes of blood recommended the use of stimulants hemopoiesis [pentauxil, tesen, folic acid (vitamin BC), cyanocobalamin (vitamin B12)].
Prevention of poisoning. When working with aromatic hydrocarbons must comply with the measures of protection, regulated by sanitary standards (EQSs benzene - 5 mg/m3, MPC toluene - 50 mg/m3, xylene-50 mg/m3, naphthalene - 20 mg/m3), as well as sanitary rules and instructions for the individual industries. Work with aromatic hydrocarbons should be conducted with pressurized equipment respecting the continuity of the process and the availability of effective ventilation. To prevent chronic poisoning is important preliminary and periodic (1 to 2 times per year) of medical examinations. For diagnostic purposes is widely used definition in the urine products of oxidation of aromatic hydrocarbons. Cm. also Aniline, Hydrocarbons.

Aromatic hydrocarbons, hydrocarbons, in structure of which there is a cyclic group. Group A. W. are benzene and its derivatives, aromatic compounds with two benzene rings (diphenyl and ego derivatives), hydrocarbons with condensed rings (inden, naphthalene and its derivatives), multicore hydrocarbons with the condensed heterocyclic rings and their analogues.
Benzene aromatic hydrocarbons, mainly liquid, part of a solid body with characteristic aromatic odour. Are used as solvents and as a source products in the synthesis of plastics, synthetic rubber, dyes, paints, insecticides, pharmaceuticals and as a high-level components of motor fuel. Benzene, toluene, xylene get in the distillation of bituminous coal and oil. Polynuclear aromatic hydrocarbons contained in the products of natural origin (oil, oil bitumen and others), and also formed during thermal processing of organic raw materials (dry distillation, Krekenava, coking and coking).


Couples A. W. in high concentrations have drug and partly convulsive effect. Acute poisoning death from respiratory arrest. The risk of acute poisoning in the application of A. W. great, especially when working in confined spaces. Even more dangerous chronic poisoning, which are characterized by heavy defeats of the blood and blood-forming organs. Individual aromatic hydrocarbons are not the same. The most severe chronic poisoning causes benzene (see). In case of poisoning derivatives of benzene there is damage to the liver, disorders of the nervous system, endocrine organs, particularly the adrenal gland, metabolism vitamin C. Irritant effect homologues of benzene on the skin increases with the number of methyl groups from benzene to trimethylbenzene (mesitilene). A. W. with four methyl groups have little irritating effect. Substances branched chains and unsaturated chains have a great irritant effect with long chains - less.
Very large toxic properties of aromatic amino - and nitrocompounds, which is primarily associated with their ability to turn the oxygenated hemoglobin into methemoglobin with the occurrence of hypoxia and hypoxia. Some nitro compounds (trinitrotoluene) are typical poisons liver. Aromatic amino compounds, especially dual core (beta-naphtylamine, benzidine, dianisidine), can cause malignant and benign tumors of the bladder. At the substitution of hydrogen with the halogen in benzene ring aromatic hydrocarbons purchase of narcotic and irritating properties. At the substitution of hydrogen with the halogen's in the side chain are formed products, is very irritating to the respiratory tract and mucous membranes of eyes. Toxicity them increases with the number of the halogen's atoms in the molecule. Naphthalene and its derivatives affect the nervous system, gastrointestinal tract, kidneys and cause irritation to the upper respiratory tract and skin. For all A. W. the specific changes in the blood (hemolysis of erythrocytes, the emergence of Taurus Heinze, anemia). When the effects of fumes and dust A. W. there is a clouding of the lens. Cataract is associated with a decrease in the content of homocysteine in the body in detoxification of the poison. Connections multicore A. W. with condensed rings inherent carcinogenic activity of a number of authors put in direct dependence on the contents A. W. 3-4-benzpyrene. Tumors usually occur in direct contact with these A. I., sometimes in distant organs.
Existing sanitary norms of planning industrial enterprises (SN 245-63) allow for the content of benzene in the air of working premises in a concentration not more than 20 mg/m3, toluene - 50 mg/m3, xylene - 50 mg/m3, naphthalene - 20 mg/m3. The presence of carcinogenic compounds in the air of working premises is not allowed. When working with A. W. you must comply with the measures of protection, regulated by the specified norms and sanitary rules and instructions for the individual industries. To prevent chronic poisoning is important preliminary and periodic (once a year) medical examination of working with A. W. For diagnostic purposes, the determination in urine oxidation products A. W. A number of authors propose a definition in biosubstrata of benzene and of products of oxidation of toluene (benzoic and hippuric acid) as "exposure test" for the evaluation of product concentration in the air of working premises. Important is the determination in urine concentrations of organic sulphates.
In the case of lung acute poisoning treatment is not generally required (in the event of excitation appoint bromides, Valerian drops, it is recommended peace). In severe cases, resort to artificial respiration, the appointment of oxygen or Carbogen. For disorders of blood type caffeine under the skin and per os together with acetylsalicylic acid or amidopirina. Epinephrine is contraindicated. Vomiting - intravenous infusion of 20 g 40% glucose solution. The irritation of the mucous membranes - sodium inhalation; rinse eyes with a 2% solution of drinking' soda.
When expressed! changes of blood to the use of stimulants blood (pentauxil, tesen, folic acid, vitamin B12 and other). Cm. also
Hydrocarbons.