Solvents

Solvents organic or inorganic liquids or mixtures which are applied for dissolving of various substances.
Solvents are used in many branches of chemical industry, in manufacture of rubber and rubber products, instrument and mechanical engineering, for the receipt of paintwork materials, footwear and leather goods industries, in medical industry, laboratory fact, etc.
The most common and universal inorganic water is the solvent. To organic solvents are hydrocarbons (see), alcohols (see) and esters (see), vegetable and mineral oils and other
Various organic solvents are on the body or mainly narcotic (see Ethyl alcohol, Acetone), or an organic cause damage to the nervous system (see Carbon sulfide, Methyl alcohol), disruption of the blood system (see Benzene), primary defeat of the liver (see Chlorinated hydrocarbons). In addition to toxicity, for hygienic assessment of solvents are set volatility (the maximum possible concentration of solvent vapour in the air) and the ability to be absorbed through intact skin. Contact solvents with the skin is accompanied by the appearance of dryness, cracks, dermatitis.
Prevention activities. Substitution in the preparation adhesives, varnishes, paints most harmful solvents (benzene, carbon disulfide, dichloroethane, tetrachloride carbon, aviation gasoline) is less toxic. Mechanization, automation and sealing of production processes with solvents. When you save the manual work - using devices and instruments that restrict the sprinkling of the solvent; the use of workplace tanks with a well-fitting lids opened as needed; perhaps more complete shelter of jobs with the equipment of local exhaust ventilation (like hoods). The prohibition to use solvent for cleaning hands from contamination. The use of aprons, oversleeves, gloves. Lubrication hands protective ointments (pasta IER-1, cream biological gloves" and others) during operation and Kirauski - after work and wash with warm water and toilet soap. Preliminary and periodic medical examinations of workers.

Solvents are liquid or mixtures thereof, solvent gaseous, liquid and solid substances. Depending on purpose to solvents different requirements: good solvent ability, chemical stability, absence of chemical interaction of the dissolved substance, the appropriate temperature boiling and freezing, fire resistance, low toxicity, etc. Solvents, used for medical and pharmaceutical purposes, should have a high degree of purity. About purity solvents are judged by transparency, colorless, boiling point, refractive index, absorption spectra and other
Dissolving ability of solvents usually increases with increasing temperature (solubility of gases decreases). In addition, dissolving ability to a great extent can influence of impurities and additives. The most solvents hygroscopic, for their drying use dehumidifiers (aluminum oxide, anhydrous calcium chloride, sulphate, calcium, silica gel, pjatiokisi phosphorus and other).
Inorganic solvents. The most common and universal solvent is water. In it in different quantities can be solved nearly all substances. Water - main solvent and for medicinal substances. However, there are medications that it is practically insoluble, and some are hydrolysis (see). In aqueous solutions can develop microorganisms. As a solvent sometimes used mercury which dissolved metals, forming with them amalgam (table. 1).

Table 1. Characteristics of some inorganic solvents

Organic solvents. These include hydrocarbons (see): aliphatic - pentane, hexane, heptane, and others; alicyclic - cyclopentane, cyclohexane, decalin and others; aromatics - benzene, toluene, xylene and other; mixtures of hydrocarbons - gasoline, kerosene, petroleum ether (table. 2). Hydrocarbons well dissolve fats, oils, resins, rubber, etc. In the water they practically do not dissolve. They are volatile and flammable (pair them with air can form explosive mixtures). Many toxic hydrocarbons (see below).
Haloid-producing hydrocarbons, aliphatic series - methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane and other; aromatic series - chlorobenzene, dichlorobenzene, etc. - flame or nonflammable liquid used to extract essential oils from medicinal raw materials and other

Table 2. The most important characteristic of organic solvents

Alcohols and fireparty: applied usually lower alcohols with temperature instrumentation from 66 to 205 degrees (methyl, ethyl, propyl and others)- They dissolve in water in any ratio and can be used both in pure form and in the form of water solutions. Excellent solvent serves fluids glycol dioxane - easily movable liquid, temperature boiling 101,32°, miscible with water in any ratio.
Simple and complex ethers. Simple ether, or ethyl ester (see), widely used in medicine. Of esters greatest application have esters of acetic acid (ethyl acetate isopropylacetate and others). They have a pleasant smell, insoluble in water. Are used in the paint industry, etc. in Addition, as a solvent used amines (see) - dimethylamine, ethylamine, diethylamine and others; aminoalcohols - ethanolamine (see) and others, ketones (acetone (see), methyl ethyl ketone and other; glycols - ethylene glycol and others; organic acid formic acid (see Methyl alcohol), acetic acid (see), pyridine and mn. other
Medication, insoluble in water, used as indifferent solvents vegetable oil and mineral oil (see). From vegetable oils in medicines for external use use sunflower, and injection - peach oil. To mitigate the effects of medicinal substances (iodine, tannin and other) is used glycerin (see).