ALCOHOLS

From Big Medical Encyclopedia

ALCOHOLS — a class of the organic compounds which are a part of various natural products and widely used in many fields of medicine, chemistry, the equipment, etc. Many S. and their derivatives are used in synthesis of pharmaceuticals; adrenaline (see), sincaline (see) and other S. play an important role in a metabolism. Various types of the organic compounds supporting spirit groups are the major components metabolism and energy (see). Alcohol (see) apply as a desinfectant and solvent. Pages are mother substances or solvents in production of many types of synfils, plasts, paints and varnishes, detergents, dyes, perfumery products. A row C. represents considerable professional harm, poisonings with them on the corresponding productions and in life can be very serious. One-atomic S. possess narcotic action, is highly toxic methyl alcohol (see), unsaturated S. show irritant action. Two - and polyatomic S., except for ethylene glycol (see. Antifreeze ), malotoksichna. Pages are eurysynusic in a plant and animal life.

Pages are derivatives hydrocarbons (see), containing one or several hydroxylic groups at saturated carbon atoms (hydroxyls, OH-group). At related S. of phenols (see) OH group is in an aromatic ring, in enols (see) — at a double carbon-to-carbon linkage. Pages (the general formula to-rykh ROH where R is the hydrocarbon radical) depending on character of the radical of R divide into acyclic, or aliphatic (alkanols), alptsiklichesky (cycloalkanols), aliphatic aromatic (aralkanola) and heterocyclic. The number of OH-group in a molecule C. characterizes so-called atomicity of S.: connections with one OH group call one-atomic S. (alcohol), with two OH groups — diatomic, or glycols (see), with three OH groups — triatomic, napr, glycerin (see), from a neskolkikhma OH groups — polyatomic, e.g. sorbite (see). Alcohols, at to-rykh OH group is at primary carbon atom, call primary (their general formula ISN2ON), alcohols with OH group at secondary carbon atom — secondary (the general formula R 2 CHOH), with OH group at tertiary carbon atom — tertiary (the general formula R 3 COH). According to the International classification of the name C. form from names of the corresponding hydrocarbons, to the Crimea add the termination - ol, - a diol, - a trial etc., and specify by figure situation IT - groups. For example, CH 3 CH 2 OH — ethanol, CH 3 CH 2 CH 2 CH 2 OH — butanol-1, CH 3 CHOHCH 2 OH — a pro-pan-diol-1,2. Also rational names — methyl, ethyl, propyl alcohols, isoamyl alcohol are common (CH 3 ) 2 CHCH 2 OH — and so-called generic names — benzyl alcohol, ethylene glycol, glycerin, menthol, etc.; sometimes apply the term «carbinols» to the name C. (from group — COH), for example (C 6 H 5 ) 3 COH — triphenyl carbinol.

The lowest one-atomic S. represent colorless liquids, well soluble in organic solvents also being good solvents. Methyl, ethyl, propyl and isopropyl S. mix up with water in every respect and possess a characteristic spirit smell; Pages with a chain length of 4 — 5 carbon atoms restrictedly of a rastvorima in water also have a pungent («fusel») smell; more high-molecular S. in water are insoluble; the highest S. are solid matters. The elementary of two - and triatomic S. — the viscous liquids which are mixing up with water. Pages boil at much more high temperature, than the corresponding hydrocarbons, owing to the association of molecules C. caused by intermolecular hydrogen bindings. From isomeric S. the most high temperatures of boiling at primary, and the lowest — at tertiary isomers. The lower alcohol forms constant boiling mixtures with water and various organic compounds (see. Solutions ), what is used, e.g., for receiving anhydrous (absolute) alcohol. S.'s reactions are connected by hl. obr. with bond breaking O — H or R — OH, and also with hydrogen abstraction from the radical of R. As S. have properties very weak to - t, they form with alkali and nek-ry other metals soleobrazny connections — alcoholates (ROH + Na — >* RONa + 0,5H 2 ), to-rye use, e.g., for receiving ethers: CH 3 ONa + C 2 H 5 Br -> CH 3 OC 2 H 5 + NaBr. At interaction with carboxylic to-tami and their derivative S. give esters: With 2 H 5 OH + CH 3 COOH -> CH 3 COOC 2 H 5 + H 2 O, are similarly formed ethers C. with inorganic to-tami, napr, the phosphates C. playing an essential role in bio-chemical processes. At action on S. strong to - the t (or reagents with similar properties) depending on S.'s structure and reaction conditions happens their dehydration to formation of ethers or unsaturated hydrocarbons (olefins):

tertiary Pages are most easily dehydrated to olefins. Primary S.' oxidation leads to education aldehydes (see) or carboxylic acids (see): Oxidation of primary alcohols

secondary S. are oxidized in ketones R 2 CHOH -> R 2 CO; these reactions are catalyzed by enzymes alkogoldegidrogenazam (see). Tertiary S.' oxidation or does not happen, or it goes with splitting of the hydrocarbon radical.

Serve as industrial methods of receiving S. hydration of olefins (in ethyl, isopropyl and tertiary butyl S.'s production), recovery of aldehydes and ketones. A hydrogenation of carbon oxide receive methyl alcohol. Ethyl and butyl S. is made commercially also with the help mikrobiol. processes of fermentation of sugars (see. Fermentation ). For a lab. various S.' synthesis use reactions between carbonyl and metalloorganic compounds and other methods. Widely apply distillation to receiving the isolated S. and distillation (see).

Pages determine by colorimetric methods (see. Colorimetry ) on the basis of reaction with n-dimethylaminobenzaldehyde, vanillin and other reactants, and also by means of gas-liquid chromatography (see). Widely apply preliminary quantitative transformation of S. into characteristic derivatives (esters, urethanes, etc.), with the subsequent chromatography and other methods.

The basic element of S. — OH group — is not only a part actually of S., but also molecules of many multifunctional natural compounds (carbohydrates, proteins, lipids, vitamins, steroids, alkaloids, etc.). Nek-ry one-atomic S., hl. obr. in the form of esters, treat products of metabolism of plants (hexene-3-ol-1, benzylic S., geraniol, etc.) and serve as pheromones insects (see), napr, bombikol, but in organisms of the highest animals usually do not meet.

Alcohols as professional harm — see in articles Amyl alcohol , Butyl alcohol , Denatured alcohol , Poisonings , Solvents , Fusel oils , Poisons industrial etc.


Bibliography: Thorns And. Modern organic chemistry, the lane with English, t. 1, M., 1981.


A. I. Tochilkin.

Яндекс.Метрика