SOLVENTS — the liquids representing individual organic or inorganic compounds or their mixes capable to dissolve various substances. Rubles find broad application in medicine for preparation of liquid dosage forms, liquids for disinfection, disinsection, deodorization, for preparation of solutions of the reagents used in biochemical, clinical, sanitary and hygienic and analytical pharmaceutical laboratories. In large numbers of R. use in pharmaceutical industry, and also in production of synfils, films and other polymeric materials, for cleaning of clothes etc.
R. applied in medicine and pharmacy shall have good dissolving capacity, thermal stability, stability in relation to the oxidizing agents, and also to light; they shall not have corrosive action on the equipment and a container used for their storage. Whenever possible R. shall not be toxic, vzryvo-and flammable. Additional requirements depending on their appointment can be imposed to R. E.g., for extractions (see) and chromatography (see) select R. having selective (selection) dissolving capacity in relation to certain substances.
One of the main characteristics of solvent is its dissolving capacity. At dissolution of low-molecular (usually crystal) substances and gases dissolving capacity is defined by concentration of saturated solution of substance in this solvent at a certain temperature and solubility of substance is expressed in the same units, as (usually the number of grams of solute necessary for receiving saturated solution, in 100 and this solvent). At dissolution of polymers, including and biopolymers, dissolving capacity of R. is measured by so-called number of dilution, a cut represents the size of the largest volume of the liquid which is not dissolving polymer, to-ry it is possible to add to this volume of solution of polymer, without causing its sedimentation. The more the number of dilution, the is more considerable dissolving capacity of R. of polymers.
Dissolving capacity depends by nature R. Izvestno that polar solvents (e.g., water), molecules to-rykh have considerable dipole moments (see. Molecule ), have big dissolving capacity in relation to polar substances. Unpolar R. — liquids with small dielectric permeability (see), napr, benzene, unpolar substances well dissolve.
Dissolving capacity sometimes considerably changes at introduction to R. of various additives. So, 100th weight. h hexane and 50th weight. h methanol do not mix up with each other and form two-layer system. Addition to this system 0,5 ves.ch. a dichloroethane leads to full mutual dissolution of liquids. Sometimes dissolving capacity of R. increases at addition to them of small amounts of salts, napr, addition of potassium perchlorate (KClO 4 ) 2,4 dinitrophenols in water increase solubility. Substantial increase of dissolving capacity of water in relation to unpolar substances, napr, to hydrocarbons, is observed at addition to water detergents (see), [[ | washed SOAPS ]] (see). Dissolving capacity of R., as a rule, increases with temperature increase, however at dissolution of gases, nek-ry liquids and solids dissolving capacity of R. at temperature increase decreases.
At practical use of R. it is often necessary to know degree of their purity, to-ruyu define by measurement of density, index of refraction, temperatures of freezing and boiling, conductivity, etc. R. consider pure if it does not contain such impurity and in such quantities, to-rye would interfere it with use for these specific goals.
The most widespread classification of R. is chemical, according to a cut R. subdivide all on inorganic and organic. Carry a number of the liquids representing inorganic compounds to inorganic R. From them the greatest practical value has water (see), being good solvent for many inorganic and organic compounds. The role of water as solvent and in the processes proceeding in the biosphere of Earth is huge.
Carry the liquids which are individual organic compounds or their mixes to organic R. Organic R. well dissolve fats, oils, pitches, polymers and many other substances. Organic R.' most — flying and combustible substances, couples to-rykh with air form explosive mixes. During the work with them it is necessary to follow the corresponding safety regulationss and fire-prevention protection. As examples of the individual organic compounds used as R. can serve hydrocarbons (see) — benzene (see), N hexane, toluene (see), cyclohexane; chlorderivatives of hydrocarbons — dichloroethane (see), benzene chloride, methylene chloride, chloroform (see), perchloromethane (see); alcohols (see) — amyl alcohol (see), isoamyl alcohol, methyl alcohol (see), propyl alcohol, alcohol (see); ethers (see); glycols (see) and their ethers — ethylene glycol (see. Antifreeze ); ketones (see) — acetone (see); nitroderivatives of hydrocarbons — nitrobenzene (see); other organic solvents — pyridine (see), carbon sulfur (see), acetic acid (see), etc. Treat the solvents representing mixes of organic compounds gasolines (see), petroleum ether (the hydrocarbon mixture received from light distillates of distillation of oil or from associated petroleum gases), turpentine (see), etc.
See also Solutions .
Occupational health during the work with solvents
San. - a gigabyte. the following properties P. matter: temperature of boiling, steam tension, a volatility, water solubility and fats, toxicity of the solvent and the formed metabolites.
The river, having a high volatility (acetone, benzene, gasoline, a dichloroethane), are most dangerous concerning air pollution of production rooms. High solubility of organic R. in water (ethyl and methyl alcohols, acetone, ethers, etc.) confirms slow saturation of blood by them and insignificant removal of such R. from an organism through respiratory tracts. Good solubility of R. in fats and the high size of coefficient of its distribution in system oil — water (e.g., benzene, a dichloroethane, tricresyl phosphate) allow it to collect quickly in the fabrics and cells rich with lipids, in particular in c. N of page, and also it is easy to get through integuments.
In the conditions of industrial production usually apply mixes of organic Rubles. Widespread solvent «N® 646 contains toluene, butanol, ethanol, butyl acetic ether, etiltsellozol and acetone, i.e. substances, physical. - chemical and toxic properties to-rykh are various.
At hron. poisonings with organic R. the wedge, a picture depends by nature River. Permanent changes in c. the N of page can cause methyl alcohol, carbon sulfur, trichloroethylene; harmfully benzene, its homologs and derivatives affect blood and the hemopoietic bodies; chlorinated hydrocarbons can cause dystrophic changes in a liver, kidneys and other parenchymatous bodies. Hron. poisonings with organic R. are characterized by the general weakness, headaches, weight reduction (weight) of a body, frequent dizzinesses, nausea, vomiting, lack of appetite, easing of memory. Cardiac disturbances, attacks of stenocardia, nevrol are possible. frustration. The long contact with organic R. causes a xeroderma, its reddening and puffiness, an itch, sometimes eczema.
At acute poisonings of R. first of all the symptoms reminding symptoms of poisoning with drugs are observed. At acute poisoning (see) easy degree the fever, weakness, dizziness, nausea, uncertain gait appear. Sometimes note irritation of a conjunctiva and a mucous membrane of upper respiratory tracts. At the acute poisoning of average degree passing into a serious poisoning, pulse becomes frequent and weak, there are short wind, vomiting, there comes the loss of consciousness, coma, spasms develops.
First aid and emergency treatment
At acute poisoning it is necessary to remove immediately the toxic solvent which was injured from an area of coverage, to quickly take off the clothes which became wet in solvent and footwear, heat to cover and take out it on fresh air or to well aired room. Inhalations by the moistened oxygen, intravenous administration of 20 — 30 ml of 40% of solution of glucose from 5 ml of 5% of solution ascorbic to - you, cardiacs — camphor (20% solution), caffeine-sodium benzoate (10% solution), Cordiaminum on 1 — 2 ml subcutaneously, calmatives, strong tea are shown. At respiratory depression inhalation of Carbogenum several times 5 — 10 min., subcutaneously is recommended to 1 ml of 10% of solution of Corazolum. According to indications — an artificial respiration, a cut it is necessary to carry out carefully, taking into account a possible fluid lungs. In hard cases immediate hospitalization is necessary.
Treatment acute and hron. poisonings with organic R. etiological, taking into account toxic properties of specific solvent, and also pathogenetic and symptomatic.
Measures of the prevention
All R. shall conform to the state standards established on them. Use as solvent of benzene is forbidden, use of a dichloroethane and perchloromethane is limited. The gigabyte is carried out. the standardization of compoundings limiting highly toxic R.' maintenance in paints, glues, mastics and other structures.
During the development of new technology are preferable to pressurize, whenever possible, the productions which are not connected with R. Sleduyet's heating the equipment and to exclude contact working with P, Laboratory works with small amounts of R. shall be performed in an exhaust case under draft, using the devices which are not allowing pollution of integuments and clothes (automatic pipets, etc.). The design of a container for R.'s storage shall provide the minimum open surface of evaporation. Cleaning of a container from under solvents needs to be made in the mechanized way in specially equipped pressurized devices by washing of a container with hot water using detergents and the subsequent its steaming. Mopping, walls and the equipment P. is forbidden.
Workers shall be provided with overalls and individual protection equipment according to acting a dignity. - a gigabyte. norms. At a possibility of hit of R. on integuments use protective pastes (HIOT-6, PM-1, «Invisible gloves», etc.), to-rye later work wash away water.
Working with R. undergo preliminary medical examination, and then periodic medical examinations at revenues to work (see. Medical examination ). Persons under 18 and pregnant women from the moment of establishment of pregnancy and during breastfeeding of the child are not allowed to work with organic R.
See also Maximum allowable concentrations .
Bibliography: Vaysberger A., etc. Organic solvents, physical properties and methods of cleaning, the lane with English, M., 1958; Occupational diseases, under the editorship of A. A. Letavet, etc., page 258, M., 1973; The Guide to occupational health, under the editorship of F. G. Krotkov, etc., t. 2, page 222, M., 1963; The Reference book on professional pathology, under the editorship of JI. N. Gratsianskoy and V. E. Kovshilo, JI., 1981; Chemical goods, Reference book, sost. T. P. Unanyants, etc., t. 1 — 4, M., 1967 — 1971; Sh t e r e N-g and r R. Ya c. Occupational health in productions on drawing paint coatings, M., 1974; Marsden C. Solvents guide, L., 1963.
V. P. Mishin; 3. A. Volkova (gigabyte.).