Ethyl Alcohol

ETHYL ALCOHOL, wine spirit, alcohol, ethyl hydroxide, ethanol, CH₃CH₂OH, a constant constituent of beverages obtained through fermentation (various wines, kumys, kefir). Found in nature wherever fermentation processes occur. Present in very small quantities in soil, snow, and the atmosphere. Found in fresh plant leaves, milk, and animal tissues. In humans, traces of alcohol are found in the brain, muscles, liver, and in breast milk after consumption of alcoholic beverages. Ethyl alcohol is found in urine only after very large amounts of alcohol have been consumed. In diabetic urine, it may form upon standing as a result of sugar fermentation; in the small intestines - as a result of carbohydrate fermentation. The main method of obtaining ethyl alcohol is biochemical - through the fermentation of sugars (see Fermentation), usually obtained from starch. The production of ethyl alcohol consists of several stages: 1) Preparation of starch solutions by heating water with the pre-ground raw material (potatoes, grain breads, corn). 2) Saccharification of the resulting solutions under the influence of malt amylase at 55-65°. 3) Fermentation of the formed sugars by adding yeast at 20-30°. After fermentation is complete, a liquid containing 5-10% ethyl alcohol is obtained. 4) Distillation of ethyl alcohol from the resulting 'mash.' Besides starch, molasses - a byproduct of sugar beet production, sulfite liquor - a byproduct of paper production, as well as wood, saccharified by chemical means: by the action of acids at high temperature and pressure, serve as raw materials for obtaining ethyl alcohol. Raw ethyl alcohol contains a large number of impurities, of which the most significant are the so-called fusel oils, consisting of a mixture of higher alcohols, mainly amyl alcohol. In addition, raw ethyl alcohol contains: acetaldehyde, paraldehyde, acetal, simple and complex esters, volatile fatty acids, glycerin, amines, furfural, collidine, etc. To purify ethyl alcohol, rectification is used, i.e., distillation of ethyl alcohol in special apparatus that allows separation of ethyl alcohol from substances boiling below and above it. The resulting product, called rectified spirit, usually contains up to 95% ethyl alcohol, the remainder being water and small amounts of acetaldehyde, fusel oils, etc. For further purification, ethyl alcohol is filtered through activated charcoal, which absorbs fusel oils. It is impossible to obtain anhydrous ethyl alcohol by distillation, since a mixture of 96 parts alcohol and 4 parts water boils at a lower temperature than pure alcohol. Dehydration is achieved by distilling mixtures of 96% ethyl alcohol with benzene. First, the ternary mixture is distilled off: water + ethyl alcohol + benzene, then the binary mixture: benzene + ethyl alcohol, and finally pure, anhydrous, so-called absolute ethyl alcohol is distilled. In laboratory practice, it is convenient to use the chemical method for obtaining absolute alcohol, namely - heating ethyl alcohol with quicklime for several hours (with a reflux condenser) and subsequent distillation of absolute ethyl alcohol. During this process, aldehydes are oxidized, acids are neutralized, so that ethyl alcohol is not only dehydrated but also purified. Dehydrated copper sulfate is also used for dehydration. Calcium chloride is inconvenient for this purpose, as it gives a crystalline compound with alcohol, which decomposes only at high temperature. Pure ethyl alcohol is a colorless liquid with a burning taste and a specific odor. Boiling point 78.37° at 760 mm Hg. Melting point -114°. Specific gravity at 20° - 0.78934. Ethyl alcohol burns with a colorless flame; mixes with water, glycerin, and ether in all proportions. Absolute ethyl alcohol eagerly absorbs moisture from the air, and therefore must be stored in hermetically sealed bottles. The presence of water in ethyl alcohol can be detected by clouding of the alcohol after adding gasoline or carbon disulfide to it. Traces of moisture can be detected by adding a crystal of anthraquinone and sodium amalgam to ethyl alcohol - absolute alcohol gives a green coloration, in the presence of water - red-violet. Pure ethyl alcohol should not give a violet coloration with fuchsin-sulfuric acid (test for aldehydes), should not give a red coloration with alkali and sodium nitroprusside (test for acetone), and should not contain fusel oils. The latter can be detected and quantitatively determined by Komarovsky's method: to 10 cm³ of ethyl alcohol, add 1 cm³ of a 1% solution of salicylaldehyde and carefully mix with 20 cm³ of chemically pure H₂SO₄. After 12 hours, the resulting coloration is compared with the coloration of standard solutions: pure ethyl alcohol gives a light yellow coloration, fusel oils - red. Qualitative detection of ethyl alcohol is based on the formation of iodoform from it when adding a 10% solution of caustic soda and a crystal of iodine to the liquid being tested. When heated to 60°, iodoform crystals form, which can be detected by their odor and characteristic shape under a microscope. The reaction is applicable only in the absence of a number of substances that have or can give upon oxidation the group CH₃-CO, such as acetaldehyde, acetone, lactic acid, pyruvic acid, etc. For detecting ethyl alcohol, the reaction of formation of the pleasant-smelling ethyl ester of benzoic acid is also used when adding a few drops of benzoyl chloride and caustic soda to the distillate. A similar odor is given by the methyl ester formed in the presence of methyl alcohol. When heated with a reflux condenser on a water bath with p-nitrobenzoyl chloride, ethyl alcohol quantitatively passes into p-nitro-benzoic acid ethyl ester, which after extraction from the alkaline solution with ether can be recrystallized from methyl alcohol. Melting point of p-nitro-benzoic acid ethyl ester 57°. - Quantitative determination of ethyl alcohol in aqueous solutions is based on determining its specific gravity (for which special areometers - alcoholometers are used). The Tralles alcoholometer is very common, showing the alcohol content in volume percent at 15°. The method is of course applicable for pure aqueous solutions not containing foreign impurities. Special conversion tables are used to find the specific gravity and weight percentages. Ethyl alcohol is easily oxidized to acetaldehyde and acetic acid, forms simple and complex esters, with sodium metal forms sodium alcoholate and in general gives all reactions characteristic of alcohols (see). For detecting ethyl alcohol in biological media, 2/6 of the volume is distilled from the liquid being tested. In the distillate, aldehydes are oxidized by boiling with a reflux condenser in the presence of caustic soda and silver oxide. To remove acetone and acids, it is heated with paraform and caustic soda to boiling, after which 2/6 of the volume is again distilled from the alkaline solution and the above-mentioned reactions for the formation of iodoform and benzoic acid ethyl ester are performed with the distillate. Ethyl alcohol finds extensive application both in technology and in laboratory and medical practice. Ethyl alcohol is used as a solvent in the preparation of varnishes and polishes, in a number of chemical industries, for extraction and crystallization, for the synthesis of organic dyes, pharmaceutical preparations (chloroform, iodoform, ether, etc.), for the preparation of synthetic rubber, for the preparation of various medicinal extracts, tinctures. Due to its ability to coagulate proteins, ethyl alcohol is used as a disinfectant, for storing anatomical specimens, in histological practice for fixation, as an antiseptic. Due to its low freezing point, it is used for filling thermometers for low temperatures; for preparing various vodkas, tinctures, liqueurs, cognacs, etc. Used as a skin irritant for rubbing. - Introduction of ethyl alcohol into the stomach, as well as per rectum, causes secretion of gastric juice, but the digestive capacity of such juice is below normal. In dogs, a single introduction of diluted ethyl alcohol initially causes hyposecretion, then hypersecretion, which lasts for 8-10 days. Introduction of small amounts of ethyl alcohol into the duodenum causes secretion of pancreatic juice, with an enhancement of tryptic digestion and the action of steapsin being observed. 1 g of ethyl alcohol upon combustion in the body gives 7.1 cal. Introduction of ethyl alcohol reduces the consumption of carbohydrates, fats and even proteins, although it initially increases protein breakdown for a short time. The nutritional value of ethyl alcohol, however, is greatly diminished by the poisonous effect of large amounts of alcohol on the body (see also Alcoholism).

^A- Kuzin. Ethyl alcohol in microscopic technique. Due to its ability to precipitate proteins and its hygroscopicity, E. s. is used in microscopic technique for fixing, hardening, and dehydrating tissues, as well as for dehydrating sections. As a fixative, E. s. is used in the form of 100° (absolute) or 96° alcohol or in mixture with other fixatives (sublimate, acetic acid, formalin). The duration of fixation in E. s. depends on the thickness of the object. When fixing poorly penetrable objects, E. s. is heated to 75°. When fixing in E. s., wrinkling is possible, especially in the presence of even traces of water, as well as displacement of cellular elements due to diffusion currents. Fixation with E. s. has many advantages due to its simplicity, speed, and the fact that the chemical composition of tissues fixed in E. s. changes little. Therefore, after fixation in E. s., it is possible not only to stain with almost all dyes, but also to conduct histochemical research of fixed tissues by various methods of dissolution and digestion. Absolute E. s. is especially useful in cases where it is necessary to preserve compounds soluble in aqueous fixatives, for example, glycogen, uric acid, pigments. On the other hand, E. s. damages fatty and fat-like elements (cholesterol, chromaffin substance, mitochondria, Golgi apparatus, myelin sheaths, etc.). E. s... is often used to wash out other fixatives in cases where the use of water for this purpose is contraindicated due to swelling or leaching phenomena, for example, after sublimate, as well as picric, trichloroacetic, acetic, and other mixtures. 30° E. s. is used for macerating fresh tissues¹ («Ranvier's third alcohol»). Being a solvent for many organic dyes, E. s., mostly in mixture with water, glycerin, etc., is used for preparing dye solutions and as a differentiating agent, in the latter case often with the addition of hydrochloric acid. Commercial E. s. usually contains no more than 99.8% alcohol. To obtain pure E. s., 96° alcohol is infused with barium peroxide (BaO), quicklime (CaO), calcium, or anhydrous calcined copper sulfate (CuSO₄). - Test of absolute E. s. for anhydrousness. In the presence of the slightest traces of water, clouding, formation of gas bubbles, and the appearance of an acetylene odor occur upon the addition of a grain of calcium carbide; with 3% water content, clouding also occurs upon the addition of benzene. - To obtain from E. s. of a given concentration (a%) E. s. of the desired concentration (b%), (a-b) parts of solvent (water) are added to a parts of a% concentration, and a parts of b% concentration are obtained. For example, given 95% E. s., it is necessary to prepare 70% E. s. To 70 cm³ of 95% E. s., 95-70 = 25 cm³ of water are added, and 95 cm³ of 70% E. s. are obtained. Table for diluting 95% E. s.: To obtain 1,000 cm³ of 80% E. s., add to 842 cm³ of 95% E. s., 158 cm³ of water; to obtain 1,000 cm³ of 70% E. s., add to 735 cm³ of 95% E. s., 285 cm³ of water¹; to obtain 1,000 cm³ of 60% E. s., add to 680 cm³ of 95% E. s., 370 cm³ of water; to obtain 1,000 cm³ of 50% E. s., add to 562 cm³ of 95% E. s., 438 cm³ of water. For microscopic purposes, the concentrations obtained in this way are sufficiently accurate.

G. Epstein. Ethyl alcohol from a forensic medical perspective. Of fatal poisonings by E. s., the majority are due to vodka poisoning. Pure acute poisoning is very rare; it is usually observed on the basis of organic alcoholic changes in organs as a consequence of alcoholism. Acute poisoning manifests as increased well-being, excitement, soon replaced by depression of the nervous system: difficulty in speech, unclearness of mental activity; consciousness fades, sopor sets in, pulse drops, breathing is difficult, vomiting is a common phenomenon, dangerous due to suffocation by vomit, cyanosis and asphyxia. This condition is life-threatening for 10-12 hours; timely help is of great importance. In chronic poisoning, parenchymatous organs change predominantly, especially the central nervous system (alcoholic delirium, white fever, drinking bouts). At autopsy, the picture of asphyxia is noted: liquid dark blood, engorgement of the right heart and veins, small ecchymoses, engorgement and edema of the brain and lungs, alcoholic odor during autopsy of the brain and chest, from the stomach often only a specific sharp odor of fermenting dough. The mucous membrane of the gastrointestinal tract changes depending on the concentration of alcohol and the duration of use: swollen, hyperemic, with abundant extravasates, predominantly on the greater curvature of the stomach. Alcohol is easily absorbed; its highest content in organs is obtained after 1.5-2 hours of administration, then it rapidly decreases and after 15-18 hours traces remain. A lethal dose for an unaccustomed person to alcohol is considered to be 100-200 cm³; children are especially sensitive to it; idiosyncrasy is often observed. Due to the volatility of alcohol, it is necessary to hurry with the examination, a simple device for which is Prof. Popov's apparatus, consisting of a flask into which the contents of the stomach or parts of the corpse with acidification are placed; upon heating, alcohol vapors appear first, precipitating on the walls of a long glass tube in the form of a characteristic ripple. Poisonings with vodka substitutes by most authors are attributed to methyl alcohol and pyridine bases added for denaturation of E. s.; these poisonings have sharply increased after the prohibition of vodka sales at the beginning of the World War (see Methyl alcohol, SYMPTOMS OF Poisoning).