ALDEHYDES

From Big Medical Encyclopedia

ALDEHYDES — a class of organic compounds with the general formula

where R is a hydrocarbon radical (rest); in an organism are intermediate products of a metabolism.

Certain representatives of aldehydes usually receive the name from the acid which is formed at their oxidation (for example, acetic to - that is acetic And.). Depending on type of the radical distinguish saturated, unsaturated, aromatic, cyclic And., etc. If a radical is the rest of alcohol, carboxylic to - you and so forth, the aldehyde alcohols, half aldehydes and other complex function compounds having the chemical properties inherent are formed And. and to the corresponding R-groups. At substitution of hydrogen of aldehydic group with a hydrocarbon radical turn out ketones (see), giving many similar with And. reactions. One of protozoa And. — acetic, or SN acetic aldehyde 3 — SNO, sometimes receive dehydrogenation of alcohol over heated copper.

The way of receiving is widespread And. from hydrocarbons of acetylene series by accession of water to them in the presence of the catalyst, opened by M. G. Kucherov:

This reaction is applied by synthetic production acetic to - you. Aromatic And. usually receive oxidation aromatic, the hydrocarbons having side methyl group:

or action on the corresponding hydrocarbons of carbon monoxide in the presence of NSL and the catalyst.

Features and chemical properties A. Are connected generally with properties and transformations of aldehydic group. So, the simplest of And. — ant, or formaldehyde

the aldehydic group to-rogo is connected with hydrogen, is gas; the lowest And. (e.g., acetic aldehyde) — liquids with a pungent smell; the highest And. — water-insoluble solid matters.

Thanks to presence of carbonyl group and mobile hydrogen atom A. are among the most reactive organic compounds. Majority of versatile reactions And. it is characterized by participation in them of carbonyl group. Oxidation reactions, accessions and substitutions of oxygen with other atoms and radicals concern to them.

And. will easily be polymerized and condensed (see. Aldol condensation ); during the processing And. alkalis or acids aldols turn out, e.g.:

During the eliminating of water aldol turns into crotonic aldehyde

capable to further accession of molecules (by polymerization). The polymers received as a result of condensation are collectively called aldol pitches.

At a research biol. substrates (blood, urine etc.) the sum of the reducing substances gives positive effect of the reactions based on oxidation of aldehydic group. Therefore these reactions, though are applied to quantitative definition of sugar (glucose) on Hagedorna — to Janszen, and also Nilander, Gaynes, Benedict's tests and so forth, but cannot be considered as specific.

And. play a large role in biol. processes, in particular biogenic amines in the presence of enzymes of aminoxidases turn into Ampere-second the subsequent their oxidation in fatty acids.

Radicals And. are of higher fatty acids molecular composition plasmalogens (see). Vegetable organisms in processes of photosynthesis for assimilation of carbon use ant A. Vyrabatyvayemye plants essential oils consist generally from cyclic unsaturated And. (anisic, cinnamon, vanillin, etc.).

At spirit fermentation under the influence of enzyme carboxymanholes of yeast there is a decarboxylation pyroracemic to - you to education acetic And., turning by recovery into alcohol.

And. are widely used in synthesis of many organic compounds. In medical practice are applied as directly And. (see. Formalin , Paraldehyde , Citral ), and the synthetic derivatives received from And., napr, urotropin (see. Geksametilentetramin ), Chlorali hydras (see), etc.

See also Ant aldehyde , Acetaldehyde .

Aldehydes as professional harm

And. are widely applied in industrial production of synthetic resins and plastic, the vanilinokrasochny and textile industry, in the food industry and perfumery. Formaldehyde is applied by hl. obr. in production of plastic and artificial pitches, in the tanning and fur industry etc.; acrolein — at all productions where fats are exposed to heating to t ° 170 ° (foundry workshops — drying of cores with an oil krepitel, the electrotechnical industry, the oil milling plants and salotopenny production etc.). In more detail — see articles devoted separate

to A. Vsa A., especially the lowest possess the expressed toxic action.

And. mucous membranes of eyes and upper respiratory tracts irritate. On the nature of all-toxic action And. are drugs, however the narcotic effect considerably concedes them to irritating. Degree of manifestation of intoxication is defined along with the size of the operating concentration also by character of the radical and as a result — change physical. - chemical properties A.: the lowest And. (well soluble and high-volatile substances) possess sharp irritant action on upper parts of a respiratory organs and rather less expressed narcotic action; at increase in length of a hydrocarbon chain of the radical solubility and a volatility And. fall therefore irritating decreases, narcotic action does not accrue; irritant action nonlimiting And. is stronger, than at limit.

Mechanism of toxic action And. it is connected with high reactivity of carbonyl group And., edges, reacting interactions with fabric proteins, causes primary irritating effect, reflex reactions of c. N of page, dystrophic changes of internals etc. Besides, getting to an organism, And. are exposed to various biochemical transformations; in this case toxic effect on an organism is had not And., but products of their transformations. And. are slowly brought out of an organism, are capable to kumulirovat, than development hron speaks. poisonings which main displays are observed first of all in the form of pathological changes of a respiratory organs.

First aid at an otravloniya aldehydes. To bring the victim to fresh air. To wash out eyes of 2% caustic solution. Alkaline and oil inhalations. At the phenomena of asphyxia — inhalation of oxygen. According to indications of means, the stimulating cordial activity and breath, calmatives (bromides, a valerian). At painful cough — mustard plasters, banks, drugs of codeine. At poisoning through a mouth — gastric lavages, in 3% solution of sodium bicarbonate, crude eggs, proteinaceous water, milk, salt laxatives. At hit on skin — washing by water or 5% spirit of ammonia.

See also articles devoted to separate aldehydes.

Prevention

Sealing and automation of productions. Ventilation of rooms (see. Ventilation ). Use of individual means of protection, e.g. the filtering gas mask of brand «A» (see. Gas masks ), overalls (see. Clothes ) etc.

Maximum allowable concentrations in the atmosphere of production rooms: for acrolein — 0,7 mg/m 3 , for acetic aldehyde, oil and propponovy aldehydes — 5 mg/m 3 , for formaldehyde and crotonic And. — 0,5 mg/m 3 .

Definition of aldehydes. In total And. totally are determined by a bisulfite method by binding by acid sodium sulfate or colorimetric — with fuksinosernisty to - that. The polyarografichesky method (Petrova — Yakovtsevskaya) is developed, spektrofotometrichesky (Wexler).

See also Poisonings , Poisons industrial .

Bibliography

Bauer K. G. The analysis of organic compounds, the lane with it., M., 1953; Nesmeyanov A. N. and Nesmeyanov N. A. Beginnings of organic chemistry, book 1 — 2, M., 1969 — 1970.

Professional harm — Amirkhanova G. F. and Latypova Z. V. Experimental justification of maximum allowable concentration of acetic aldehyde in water of reservoirs, in book: Prom. zagryazn. reservoirs, under the editorship of S. N. Cherkinsky, century 9, page 137, M., 1969, bibliogr.; Bykhovskaya M. S., Ginzburg S. L. and Halizova O. D. Methods of definition of harmful substances in air, page 481, M., 1966; Van Wen-yan, Materials to toxicology of aldehydes of a fatty series, in book: Materials on toksikol. the substances applied in a pro-recension. plastich. masses and sintetich. rubbers, under the editorship of N. V. Lazarev and I. D. Gadaskina, page 42, L., 1957, bibliogr.; Harmful substances in the industry, under the editorship of N. V. Lazarev, t. 1, page 375, L., 1971, bibliogr.; Gurvits S. S. and Sergeyev T. I. Definition of trace amounts of aldehydes in air of production rooms by method of a derivative polyarografiya, the Gigabyte. work and the prof. having got sick., No. 9, page 44, 1960; Trofimov L. B. Comparative toxic effect of crotonic and oil aldehydes, in the same place, No. 9, page 34, 1962, bibliogr.; Cai L. M. To a question of transformations of acetic aldehyde in an organism, in the same place, No. 12, page 33, 1962, bibliogr.; Hine C. H. and. lake of Studies on the toxicity of glycid aldehyde, Arch, environm. Hlth, v. 2, p. 23, 1961, bibliogr.; Jung F. u. Onnen K. Bindung und Wirkungen des Formaldehyds an Erythrocyten, Naunyn-Schmiedeberg's Arch. exp. Path. Pharmak., Bd 224, S. 179, 1955; Nova H. Touraine R. G. Asthme au formol, Arch. Mai. prof., t. 18, p. 293, 1957; Skog E. A lexicological investigation of lower aliphatic aldehydes, Actapharmacol. (Kbh.), v. 6, p. 299, 1950, bibliogr.

B. V. Kulibakin; N. K. Kulagina (prof).

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