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Acetaldehyde belongs to organic compounds and is included in the class of aldehydes. What properties does this substance have, and what does the formula of acetaldehyde look like?

general characteristics

Acetaldehyde has several names: acetaldehyde, ethanal, methyl formaldehyde. This compound is an aldehyde of acetic acid and ethanol. Its structural formula is as follows: CH 3 -CHO.

Rice. 1. Chemical formula acetaldehyde.

The peculiarity of this aldehyde is that it occurs both in nature and is produced artificially. In industry, the production volume of this substance can be up to 1 million tons per year.

Ethanal is found in food products, such as coffee, bread, and also this substance is synthesized by plants during metabolism.

Acetaldehyde is a colorless liquid with a pungent odor. Soluble in water, alcohol and ether. Is poisonous.

Rice. 2. Acetaldehyde.

The liquid boils at a fairly low temperature - 20.2 degrees Celsius. Because of this, problems arise with its storage and transportation. Therefore, the substance is stored in the form of paraldehyde, and acetaldehyde is obtained from it, if necessary, by heating with sulfuric acid (or any other mineral acid). Paraldehyde is a cyclic trimer of acetic acid.

Methods of obtaining

Acetaldehyde can be obtained in several ways. The most common option is ethylene oxidation or, as this method is also called, the Wacker process:

2CH 2 =CH 2 +O 2 -2CH 3 CHO

The oxidizing agent in this reaction is palladium chloride.

Also, acetaldehyde can be obtained by reacting acetylene with mercury salts. This reaction bears the name of the Russian scientist and is called the Kucherov reaction. As a result chemical process an enol is formed, which isomerizes to an aldehyde

C 2 H 2 +H 2 O=CH 3 CHO

Rice. 3. M. G. Kucherov portrait.

Introduction

Today, millions of chemical compounds are known. And most of them are organic. These substances are divided into several large groups, the name of one of them is aldehydes. Today we will look at a representative of this class - acetaldehyde.

Definition

Acetaldehyde is an organic compound of the aldehyde class. It can also be called differently: acetaldehyde, ethanal or methyl formaldehyde. The formula of acetaldehyde is CH 3 -CHO.

Properties

The substance in question has the appearance of a colorless liquid with a sharp suffocating odor, which is highly soluble in water, ether and alcohol. Since the boiling point of the compound under discussion is low (about 20 o C), only its trimer, paraldehyde, can be stored and transported. Acetaldehyde is obtained by heating the said substance with inorganic acid. This is a typical aliphatic adhehyde, and it can take part in all reactions that are characteristic of this group of compounds. The substance tends to tautomerize. This process ends with the formation of enol - vinyl alcohol. Because acetaldehyde is available as an anhydrous monomer, it is used as an electrophile. Both it and its salts can react. The latter, for example, when interacting with the Grignard reagent and organolithium compounds, form hydroxethyl derivatives. Acetaldehyde upon condensation is distinguished by its chirality. Thus, during the Strecker reaction it can condense with ammonia and cyanides, and the product of hydrolysis will be the amino acid alanine. Acetaldehyde also enters into the same type of reaction with other compounds - amines, then the reaction product becomes imines. In synthesis heterocyclic compounds acetaldehyde is a very important component, the basis of all experiments performed. Paraldehyde, a cyclic trimer of this substance, is obtained by the condensation of three ethanal molecules. Also, acetaldehyde can form stable acetals. This occurs during the interaction of the subject in question. chemical substance with ethyl alcohol, carried out under anhydrous conditions.

Receipt

Acetaldehyde is mainly produced by the oxidation of ethylene (Wacker process). Palladium chloride acts as an oxidizing agent. This substance can also be obtained during the hydration of acetylene, which contains mercury salts. The reaction product is enol, which isomerizes into the desired substance. Another method for producing acetaldehyde, which was most popular long before the Wacker process became known, is the oxidation or dehydration of ethanol in the presence of copper or silver catalysts. During dehydration, in addition to the desired substance, hydrogen is formed, and during oxidation, water is formed.

Application

Using the compound under discussion, butadiene, aldehyde polymers and some organic substances, including the acid of the same name, are obtained. It is formed during its oxidation. The reaction looks like this: “oxygen + acetaldehyde = acetic acid.” Ethanal is an important precursor to many derivatives, and this property is widely used in synthesis
many substances. In human, animal and plant organisms, acetaldehyde is a participant in some complex reactions. It is also part of cigarette smoke.

Conclusion

Acetaldehyde can be both beneficial and harmful. It is bad for the skin, is an irritant and possibly a carcinogen. Therefore, its presence in the body is undesirable. But some people themselves provoke the appearance of acetaldehyde by smoking cigarettes and drinking alcohol. Think about it!

Acetaldehyde, which is a metabolite of alcohol, has the ability to increase the release of catecholamines, which increase the tone of resistive vessels, from adrenergic endings. Catecholamines cause oxygen starvation of the heart and body tissues, as well as tachycardia. Acetaldehyde has the ability to condense with some catecholamines, namely dopamine, with the subsequent formation of tetrahydroisoquinolines, which accumulate in brain neurons and act as false transmitters replacing catecholamines. These substances cause serious disruptions in the functioning of the central nervous system, some of them have pronounced hallucinogenic properties.

Among other things, acetaldehyde inhibits the elimination of ethanol metabolic products, which leads to impaired liver function. Thus, in biological environments human body acetic acid accumulates. Acetaldehyde slows down redox reactions, thus inhibiting the oxidation of other substances. Thus, glycerol, pyruvic acid, and fatty acids accumulate in the blood plasma, which contributes to the development of metabolic acidosis.

Often the patient's alcohol withdrawal syndrome is accompanied by increased content calcium in the blood and a decrease in glucose levels, which contributes to depression of consciousness and the development of convulsive disorders.

Alcohol, together with its breakdown products, has a capillary-toxic effect, increasing platelet aggregation, which contributes to the development of thrombosis, especially if the patient suffers from atherosclerosis. Thrombosis, in turn, can cause myocardial infarction and ischemic stroke. In this case, acetaldehyde tends to directly inhibit the contractile function of the myocardium.

When the blood plasma becomes acidified, that is, when its pH level decreases, hemoglobin, which is found in red blood cells, begins to bind oxygen worse. This, in turn, reduces the amount of oxygen that is delivered to the cells, and the development of oxygen starvation, the transition of cellular systems to an oxygen-free (anaerobic) method of glucose oxidation, which is less effective and causes further accumulation of under-oxidized compounds, and thus acidosis increases.

Authorship and editing of the text:
Head of the Department of Psychiatry and Narcology at the Alkoklinik MC, psychiatrist-narcologist Popov A.G. , psychiatrist-narcologist Serova L.A.

Our doctors

Photo of the Aloklinik Medical Center

ACETALDEHYDE, CH 3. SN: Oh, acetaldehyde, found in raw wood and wine alcohol, in wine, in many essential oils(camphor, anise, mint and others), as well as in young pea fruits. A. is one of the intermediate products formed during the alcoholic fermentation of carbohydrates (see. Fermentation). Its formation is associated with the action of carboxylase, a special enzyme found in yeast zymase, which decomposes pyrogratic acid(see) on A. and carbon dioxide: CH, . CO. COOH=CH, . CHO + C0 2. As a result of further redox-oxidative interactions, A. turns into ethanol. A. is also an intermediate product of the breakdown of glucose in the body of animals. A. is obtained by 1) oxidation of ethyl alcohol with chromic acid, manganese peroxide and sulfuric acid or with the help of catalysts (copper, silver, platinum): CH 3. CH s OH+ + 0=CH e. CHO+H a O; 2) hydration. A. is a volatile, colorless liquid that has a pleasant odor in weak dilutions; boiling point 21°, sp. V. 0.7951; A. mixes with water, alcohol, ether in any ratio; It is released from aqueous solutions by calcium chloride. From chemical properties A. the following are important. 1. Addition small quantity concentrated sulfuric acid causes the formation of paraldehyde, a liquid boiling at 124°, which does not exhibit typical aldehyde reactions. Polymerization proceeds with a significant release of heat according to the equation: ZSN 8. CHO=C e H a O s . When paraldehyde is heated with acids, depolymerization occurs, i.e. e. it turns back to A. 2. In the presence of certain substances (HC1, zinc chloride and, especially, weak alkalis) A. turns into aldoli(see): 2CH 3. CHO = CH 3. CH(OH). CH a. SNO. When A. is exposed to strong alkalis, an aldehyde resin is formed. 3. During oxidation, acetic acid is obtained from A.; СНз СНО+0 = СН 3. COOH. 4. During reduction, ethyl alcohol is formed: CH 3. CHO + H 2 = CH 3. CH 2 OH. 5. Hydrocyanic acid joins A., forming lactic acid nitrile: CH 3. CHO + + HCN=CH 3 . CH(OH). CN, from which can be obtained by saponification lactic acid(cm.). 6. Ammonium cyanide produces amino-nitrile CH 3 ■ CH(NH 2). CN, the saponification of which produces ala- HUH(CM.)- S. Bears.

See also:

• ACETATES, salts of acetic acid, are used in laboratory practice to make buffer solutions. Introduced into the body, A., like other salts fatty acids, are oxidized to carbon dioxide salts, causing an increase in blood alkalinity and...
• ACETYLENE, has a chemical formula C2H2 (formula of the structure of HC CH) and is, under ordinary conditions, a colorless poisonous gas at 0° and 26 atm. condensing into liquid. 1 l A. ...
• ACETOSONE, benzozone, C6H6C0.02.COSN„ benzoyl acetyl peroxide, white crystalline. powder, melt, at 40°, soluble in water; aqueous solutions, like hydrogen peroxide, are strong oxidizing agents; acetozone decomposes by alkalis and organic substances; when heated...
• ACETIMETER(from Latin acetum - vinegar and Greek metron - measure), a device invented by Otto to determine the amount of free acetic acid in vinegar in cases where the presence of foreign acids and...
• ACETONE, CH3-CO-CH3 (dimethyl ketone), colorless, flammable liquid with a specific gravity of 0.79 at 18°, with a pleasant odor, burning taste. Boils at 56.5°, easily dissolves in water, alcohol and ether. Acetone turns out...

Acetaldehyde (other names: acetaldehyde, methyl formaldehyde, ethanal) - belonging to the class of aldehydes. This substance is important for humans and is found in coffee, bread, ripe fruits and vegetables. Synthesized by plants. Occurs naturally and is produced in large quantities person. Formula of acetaldehyde: CH3-CHO.

Physical properties

1. Acetaldehyde is a colorless liquid with a sharp bad smell.
2. Soluble in ether, alcohol and water.
3. is 44.05 grams/mol.
4. Density is 0.7 grams/centimeter³.

Thermal properties

1. Melting point is -123 degrees.
2. The boiling point is 20 degrees.
3. equal to -39 degrees.
4. Auto-ignition temperature is 185 degrees.

Preparation of acetaldehyde

1. The main method of obtaining this substance is (the so-called Wacker process). This is what the reaction looks like:
2CH2 = C2H4 (ethylene) + O2 (oxygen) = 2CH3CHO (methyl formaldehyde)

2. Also, acetaldehyde can be obtained by hydration of acetylene in the presence of mercury salts (the so-called Kucherov reaction). This produces phenol, which then isomerizes to an aldehyde.

3. The following method was popular before the above process was introduced. It was performed by oxidation or dehydrogenation on a silver or copper catalyst.

Applications of acetaldehyde

To obtain what substances is acetaldehyde needed? Acetic acid, butadiene, aldehyde polymers and some other organic substances.
- Used as a precursor (a substance that participates in a reaction leading to the creation of the target substance) to acetic acid. However, they soon stopped using the substance we are considering in this way. This happened for the reason that acetic acid easier and cheaper to produce from metalon using the Kativa and Monsanto processes.
- Methyl formaldehyde is an important precursor to pentaerythrol, pyridine derivatives and crotonaldehyde.
- Obtaining resins as a result of the fact that urea and acetaldehyde have the ability to condense.
- Obtaining ethylidene diacetate, from which the monomer polyvinyl acetate (vinyl acetate) is subsequently produced.

Tobacco addiction and acetaldehyde

This substance is a significant part of tobacco smoke. A recent demonstration showed that the synergistic relationship of acetic acid with nicotine increases addiction (especially in individuals under thirty years of age).

Alzheimer's disease and acetaldehyde

Those people who do not have the genetic factor for the conversion of methyl formaldehyde to acetic acid have a high risk of predisposition to diseases such as Alzheimer's disease, which usually occurs in old age.

Alcohol and methyl formaldehyde

Presumably the substance we are considering is a carcinogen for humans, since today there is evidence of the carcinogenicity of acetaldehyde in various experiments on animals. In addition, methyl formaldehyde damages DNA, thereby causing development of the muscular system disproportionate to body weight, which is associated with impaired protein metabolism in the body. A study of 800 alcoholics was conducted, as a result of which scientists came to the conclusion that people exposed to acetaldehyde have a defect in the gene for one enzyme - alcohol dehydrogenase. For this reason, such patients are at greater risk of developing cancer of the kidneys and upper liver.

Safety

This substance is toxic. It is an air pollutant when smoked or from exhaust in traffic jams.