Ethanoic acid is better known as acetic acid. It is an organic compound with the formula CH 3 COOH. Belongs to the class of carboxylic acids, the molecules of which contain functional monovalent carboxyl groups COOH (either one or several). You can provide a lot of information about it, but now it’s worth noting only the most interesting facts.

Formula

You can see what it looks like from the image below. The chemical formula of acetic acid is simple. This is due to many things: the compound itself is monobasic, and it belongs to the carboxyl group, which is characterized by easy abstraction of protons (a stable elementary particle). This compound is a typical representative of carboxylic acids, since it has all their properties.

The bond between oxygen and hydrogen (−COOH) is highly polar. This causes an easy process of dissociation (dissolution, decay) of these compounds and the manifestation of their acidic properties.

As a result, the H + proton and the acetate ion CH3COO − are formed. What are these substances? An acetate ion is a ligand bound to a specific acceptor (an entity that receives something from a donor compound), forming stable acetate complexes with many metal cations. And a proton is, as mentioned above, a particle capable of capturing an electron with the electronic M-, K- or L-shells of an atom.

Qualitative analysis

It is based specifically on the dissociation of acetic acid. Qualitative analysis, also called reaction, is a set of physical and chemical methods that are used to detect compounds, radicals (independent molecules and atoms) and elements (collections of particles) that make up the substance being analyzed.

Using this method, it is possible to detect salts of acetic acid. It doesn't look as complicated as it might seem. A strong acid is added to the solution. sulfur, for example. And if the smell of acetic acid appears, then its salt is present in the solution. How it works? The residues of acetic acid, which are formed from the salt, at that moment bind with hydrogen cations from sulfuric acid. What is the result? The appearance of more molecules of acetic acid. This is how dissociation happens.

Reactions

It should be noted that the compound under discussion is capable of interacting with active metals. These include lithium, sodium, potassium, rubidium, francium, magnesium, cesium. The latter, by the way, is the most active. What happens during such reactions? Hydrogen is released, and the formation of the notorious acetates occurs. This is what the chemical formula of acetic acid looks like when it reacts with magnesium: Mg + 2CH 3 COOH → (CH 3 COO) 2 Mg + H 2.

There are methods for producing dichloroacetic (CHCl 2 COOH) and trichloroacetic (CCl 3 COOH) acids. In them, the hydrogen atoms of the methyl group are replaced by chlorine ones. There are only two ways to get them. One is the hydrolysis of trichlorethylene. And it is less common than the other, based on the ability of acetic acid to be chlorinated by the action of chlorine gas. This method is simpler and more effective.

This is what this process looks like in the form of the chemical formula of acetic acid reacting with chlorine: CH 3 COOH + Cl 2 → CH 2 CLCOOH + HCL. It’s just worth clarifying one point: this is how you get just chloroacetic acid, the two mentioned above are formed with the participation of red phosphorus in small quantities.

Other transformations

It is worth noting that acetic acid (CH3COOH) is capable of entering into all reactions that are characteristic of the notorious carboxylic group. It can be reduced to ethanol, a monohydric alcohol. To do this, it is necessary to treat it with lithium aluminum hydride, an inorganic compound that is a powerful reducing agent often used in organic synthesis. Its formula is Li(AlH 4).

Acetic acid can also be converted into acid chloride, an active acylating agent. This happens under the influence of thionyl chloride. By the way, it is an acid chloride of sulfurous acid. Its formula is H 2 SO 3. It is also worth noting that the sodium salt of acetic acid, when heated with an alkali, is decarboxylated (the carbon dioxide molecule is eliminated), resulting in the formation of methane (CH₄). And it, as you know, is the simplest hydrocarbon, which is lighter than air.

Crystallization

Glacial acetic acid - the compound in question is often called just that. The fact is that when it is cooled to just 15-16 °C, it goes into a crystalline state, as if it were freezing. Visually it really looks a lot like ice. If you have several ingredients, you can conduct an experiment, the result of which will be the conversion of acetic acid into glacial acid. It's simple. You need to prepare a cooling mixture from water and ice, and then lower a previously prepared test tube with acetic acid into it. After a few minutes it crystallizes. In addition to the connection, this requires a beaker, a stand, a thermometer and a test tube.

Harm of the substance

Acetic acid, the chemical formula and properties of which were listed above, is unsafe. Its vapors have an irritating effect on the mucous membranes of the upper respiratory tract. The threshold for the perception of the odor of this compound in the air is around 0.4 mg/l. But there is also the concept of maximum permissible concentration - a sanitary and hygienic standard approved by law. According to it, up to 0.06 mg/m³ of this substance can be in the air. And if we are talking about work premises, then the limit increases to 5 mg/m3.

The destructive effect of acid on biological tissue directly depends on how much it is diluted with water. The most dangerous solutions are those containing more than 30% of this substance. And if a person accidentally comes into contact with a concentrated compound, he will not be able to avoid chemical burns. This absolutely cannot be allowed, since after this coagulation necrosis begins to develop - the death of biological tissues. The lethal dose is only 20 ml.

Consequences

It is logical that the higher the concentration of acetic acid, the more harm it will cause if it gets on the skin or inside the body. Common symptoms of poisoning include:

• Acidosis. The acid-base balance shifts towards increasing acidity.
• Blood thickening and impaired clotting.
• Hemolysis of red blood cells, their destruction.
• Liver damage.
• Hemoglobinuria. Hemoglobin appears in the urine.
• Toxic burn shock.

Severity

It is customary to distinguish three:

1. Easy. Characterized by minor burns of the esophagus and oral cavity. But there is no blood thickening, and the internal organs continue to function normally.
2. Average. Intoxication, shock and blood thickening are observed. The stomach is affected.
3. Heavy. The upper respiratory tract and the walls of the digestive tract are severely affected, and kidney failure develops. Maximum pain shock. The development of burn disease is possible.

Poisoning from acetic acid vapor is also possible. It is accompanied by a severe runny nose, cough and watery eyes.

Giving help

If a person is poisoned by acetic acid, it is very important to act quickly to minimize the consequences of what happened. Let's look at what needs to be done:

• Rinse your mouth. Do not swallow water.
• Perform tube gastric lavage. You will need 8-10 liters of cold water. Even blood impurities are not a contraindication. Because in the first hours of poisoning, large vessels still remain intact. So there will be no dangerous bleeding. Before washing, you need to give pain relief with analgesics. The probe is lubricated with Vaseline oil.
• Do not induce vomiting! The substance can be neutralized with burnt magnesia or Almagel.
• None of the above? Then the victim is given ice and sunflower oil - he needs to take a few sips.
• It is permissible for the victim to consume a mixture of milk and eggs.

It is important to provide first aid within two hours after the incident. After this period, the mucous membranes swell greatly, and it will be difficult to reduce a person’s pain. And yes, under no circumstances should you use baking soda. The combination of acid and alkali will produce a reaction that produces carbon dioxide and water. And such a formation inside the stomach can lead to death.

Application

Aqueous solutions of ethanoic acid are widely used in the food industry. These are vinegars. To obtain them, the acid is diluted with water to obtain a 3-15 percent solution. As an additive they are designated E260. Vinegars are included in various sauces, and they are also used for canning food, marinating meat and fish. In everyday life, they are widely used for removing scale and stains from clothes and dishes. Vinegar is an excellent disinfectant. They can treat any surface. Sometimes it is added during washing to soften clothes.

Vinegar is also used in the production of aromatic substances, medicines, solvents, in the production of acetone and cellulose acetate, for example. Yes, and acetic acid is directly involved in dyeing and printing.

In addition, it is used as a reaction medium for the oxidation of a wide variety of organic substances. An example from industry is the oxidation of paraxylene (an aromatic hydrocarbon) by atmospheric oxygen into terephthalic aromatic acid. By the way, since the vapors of this substance have a sharp irritating odor, it can be used as a replacement for ammonia to bring a person out of fainting.

Synthetic acetic acid

This is a flammable liquid that belongs to substances of the third hazard class. It is used in industry. When working with it, personal protective equipment is used. This substance is stored under special conditions and only in certain containers. Typically this is:

• clean railway tanks;
• containers;
• tank trucks, barrels, stainless steel containers (capacity up to 275 dm 3);
• glass bottles;
• polyethylene barrels with a capacity of up to 50 dm 3;
• sealed stainless steel tanks.

If the liquid is stored in a polymer container, then this is for a maximum of a month. It is also strictly prohibited to store this substance together with such strong oxidizing agents as potassium permanganate, sulfuric and nitric acids.

Composition of vinegar

It’s also worth saying a few words about him. The composition of traditional, familiar vinegar includes the following acids:

• Apple. Formula: NOOCCH₂CH(OH)COOH. It is a common food additive (E296) of natural origin. Contained in unripe apples, raspberries, rowan, barberry and grapes. In tobacco and shag it is presented in the form of nicotine salts.
• Dairy. Formula: CH₃CH(OH)COOH. Formed during the breakdown of glucose. Food additive (E270), which is obtained by lactic acid fermentation.
• Ascorbic acid. Formula: C₆H₈O₆. Food additive (E300) used as an antioxidant that prevents product oxidation.

And of course, the ethane compound is also included in vinegar - this is the basis of this product.

How to dilute?

This is a frequently asked question. Everyone has seen 70% acetic acid on sale. It is bought to prepare mixtures for traditional treatment, or for use as a seasoning, marinade, additive to sauce or dressing. But you cannot use such a powerful concentrate. Therefore, the question arises of how to dilute acetic acid to vinegar. First you need to protect yourself - wear gloves. Then clean water should be prepared. For solutions of different concentrations, a certain amount of liquid will be required. Which? Well, look at the table below and dilute acetic acid based on the data.

Vinegar concentration	Initial concentration of vinegar 70%
	1:1.5 (ratio - one part vinegar to the nth part of water)

In principle, nothing complicated. To get a 9% solution, you need to take the amount of water in milliliters according to this formula: multiply 100 grams of vinegar by the initial value (70%) and divide by 9. What do you get? The number is 778. 100 is subtracted from this, since 100 grams of acid were initially taken. This makes 668 milliliters of water. This amount is mixed with 100 g of vinegar. The result is a whole bottle of 9% solution.

Although, it can be done even simpler. Many people are interested in how to make vinegar from acetic acid. Easily! The main thing is to remember that for one part of a 70% solution you need to take 7 parts of water.

Choose one correct answer. 1. Acetic acid cannot react with:

1. Acetic acid cannot react with:

1) potassium sulfate 3) ammonia

2) glycerin 4) phosphorus chloride (V)

2. Formic acid can be distinguished from other acids using:

1) solution of iron (III) chloride

2) ammonia solution of silver oxide (I)

3) litmus solution

4) bromine water

3. Dibasic saturated carboxylic acids include:

1) oxalic and valerian 3) propionic and amber

2) malonic and oily 4) amber and adipic

4. Limit higher fatty acid containing 16 carbon atoms:

1) palmitic 3) stearic

2) oleic 4) arachidonic

5. The product of decarboxylation of oxalic acid is:

1) butyric acid 3) acetic acid

2) propionic acid 4) formic acid

6. A substance that can react with both formic acid and

metanalem, has the formula:

1) NaOH 2) Cu(OH) 2 3) CH 4 4) HBr

7. Saturated carboxylic acids are:

1) croton and vinegar

2) propionic and palmitic

3) linoleic and oleic

4) stearic and arachidonic

8. Functional group – COOH is present in the molecule:

1) formaldehyde 3) acetic acid

2) ethyl acetate 4) phenol

1) CH 2 Cl – COOH 3) CH 2 I – COOH

2) CH 2 Br – COOH 4) CH 3 – COOH

10. Acetic acid interacts with:

1) sodium hydroxide and magnesium chloride

2) chlorine and water

3) sodium carbonate and magnesium

4) ethanol and ethanal

LIPIDS

Lipids are a large and diverse group of natural compounds, united by a common property - their practical insolubility in water and good solubility in organic solvents. Lipids, depending on their ability to hydrolyze, are divided into saponified and unsaponifiable.

Wax– esters of higher fatty acids and higher monohydric alcohols.

Palmitic acid cetyl ester (Spermaceti)

ǁǁ O

Palmitic acid myricyl ester (Beeswax)

ǁǁ O

Fats and oils(neutral fats) – glycerol esters of higher fatty acids. Triglycerides with limiting higher carboxylic acids (HCA), solid – fats; with unsaturated VKK, liquid – oils. If all three acids in the molecule are the same, it is a simple triglyceride; if they are different, it is a mixed triglyceride.

DEFINITION

Acetic acid(ethanoic acid, methanecarboxylic acid) is an organic substance with the formula. Weak, limiting monobasic carboxylic acid.

Chemical and structural formula of acetic acid

Chemical formula: CH3COOH

Gross formula: C2H4O2

Structural formula:

Molar mass: 60.05 g/mol.

Acetic acid is a saturated monobasic carboxylic acid. Forms acetates.

Weak acid, dissociation constant K a = 1.75 10 –5, pK a = 4.76.

Physical properties of acetic acid

Acetic acid is a colorless liquid with a sharp characteristic odor and sour taste. Hygroscopic, unlimitedly soluble in water. Exists in the form of dimers. Anhydrous acetic acid is called glacial acid because it forms an ice-like mass when it freezes.

Chemical properties of acetic acid

Acetic acid exhibits all the basic properties of carboxylic acids.

A qualitative reaction to acetic acid salts is interaction with strong acids. Acetic acid is weak and is displaced by strong acids from salt solutions, and its characteristic odor appears:

Receipt. The most cost-effective industrial method for producing acetic acid is the carbonylation of methanol with monoxide, the catalyst is rhodium salts, the promoter is iodide ions:

Biochemical method - ethanol oxidation:

Aqueous solutions of acetic acid are used in the food industry (food additive E260), household cooking, and canning. Acetic acid is used to obtain medicinal and fragrant substances, as a solvent.

Examples of problem solving

EXAMPLE 1

Exercise	Calculate the pH of a solution of acetic acid with a molar concentration of 1 mol/l, the dissociation constant of which is 1.75 10 –5.
Solution	Let us write the dissociation equation for acetic acid: Acid dissociation constant: Let us denote by x the concentration of hydrogen ions x = , then the expression for the dissociation constant will take the form: Since acetic acid is weak, then x pH is the negative decimal logarithm of the equilibrium concentration of H + ions. Since x = , then
Answer	The pH of the solution is 2.38

EXAMPLE 2

Exercise

Calculate the pH of the solution obtained by adding 5 ml of 0.1 M sodium hydroxide solution to 10 ml of 0.1 M acetic acid solution. Dissociation constant of acetic acid K a = 1.75 10 –5.

Solution

The total volume of the solution will be equal to: Ref ref ml When the solutions are drained, the following reaction occurs: Let's calculate the amounts of acetic acid and: Ex ref ref mole Ref ref ref mole According to the reaction equation, n(CH 3 COOH) = n(NaOH), and in our case n(CH 3 COOH) > n(NaOH), therefore, acetic acid is taken in excess. After the reaction occurs, the solution will contain acetic acid and sodium acetate, i.e. we got a buffer system.

Let's calculate the concentration of sodium acetate in the resulting solution:

General characteristics of acetic acid
Synonyms: ethanoic acid, glacial acetic acid, Acetic acid, CH 3 COOH
This is an organic compound. It has a characteristic sour taste and pungent odor. Although it is classified as a weak acid, concentrated acetic acid is corrosive.
In the solid state, acetic acid molecules form pairs (dimers) connected by hydrogen bonds. Liquid acetic acid is a hydrophilic (polar) protic solvent similar to ethanol and water. With a moderate relative static permittivity (dielectric constant) of 6.2, it dissolves not only polar compounds such as inorganic salts and sugars, but also non-polar compounds such as oils, and elements such as sulfur and iodine. In acetic acid, the hydrogen center is located in the carboxyl group (-COOH), as in other carboxylic acids, it can be separated from the molecule by ionization:
Acetic acid can undergo chemical reactions typical of carboxylic acids. When interacting with a base, it is converted into metal acetate and water. Reduction of acetic acid produces ethanol. When heated above 440°C, acetic acid decomposes to produce carbon dioxide and methane, or ketenes and water:
CH 3 COOH → CH 4 + CO 2
CH 3 COOH → CH 2 CO + H 2 O

Preparation of acetic acid

Acetic acid is produced by acetic acid bacteria (Acetobacter genus Clostridium and acetobutylicum):
C 2 H 5 OH + O 2 → CH 3 COOH + H 2 O
About 75% of acetic acid is synthesized for use in the chemical industry by carbonylation of methanol. In this process, methanol and carbon monoxide react to produce acetic acid:
CH 3 OH + CO → CH 3 COOH

Application of acetic acid

Acetic acid is a chemical reagent for the production of chemical compounds. The most common use of acetic acid is in the production of vinyl acetate monomer (VAM). Acetic acid is used as a solvent in the production of terephthalic acid (TPA), the raw material for polyethylene terephthalate (PET).
Esters of acetic acid are commonly used as solvents for inks, paints and coatings. Esters include ethyl acetate, n-butyl acetate, isobutyl acetate, and propyl acetate.
Glacial acetic acid is used in analytical chemistry for the evaluation of weakly alkaline substances such as organic amides. Glacial acetic acid is much weaker than water, so the amide behaves as a strong base in this environment.
Vinegar (4-18% acetic acid) is used directly as a seasoning.

Note

Concentrated acetic acid causes skin burns and irritation of mucous membranes. Rubber gloves do not provide protection, so special gloves, such as those made from nitrile rubber, must be used. Concentrated acetic acid may be flammable (if ambient temperature exceeds 39°C). Due to incompatibility, it is recommended to store acetic acid separately from chromic acid, ethylene glycol, nitric acid, perchloric acid, permanganate, peroxides and hydroxyls.

Characteristics of acetic acid

Food preservative E260 – acetic acid. It is known to all people who know at least a little about the art of gastronomy.

It is formed as a result of the natural souring of natural. During this period, and begins to ferment. In addition, acetic acid is directly involved in the metabolic process in the human body.

The food preservative has a pungent odor. The pure form acts as a colorless liquid that absorbs moisture from the environment.

It can only freeze at a temperature of -15 degrees. When frozen, many transparent crystals form.

Vinegar is 3-6% acetic acid. A 70-80% solution is already called vinegar essence. E260 is used not only in industrial production, but also in home cooking of various dishes.

Vinegar is a carbonaceous representative that has the ability to exhibit a high reaction function. As soon as it reacts with other substances, it begins to initiate compounds of functional derivatives. As a result of such reactions, salts, amides and esters are formed.

It must dissolve in water and not create mechanical impurities, and also have a set proportion of quality components.

Where is it used?

Acetic acid is mainly used in the manufacture of various preservatives and marinades.

In addition, it is also used in the industrial production of canned vegetables and confectionery products.

Often, a food preservative is used as a disinfectant and disinfectant.

However, acetic acid is used not only in the preparation of various foods, but also in other industries.

E260 in food production

Its scope of activity depends on the properties of acetic acid. Its main value lies in its taste and acidic nature.

Vinegar is divided into several types, namely: apple, balsamic, beer, cane, date, honey, raisin, palm and many others.

Acid is often used in the manufacture of marinades, which later serve as the basis for canning vegetables.

Even the most famous recipe for marinating meat for barbecue involves adding vinegar.

It has strong antibacterial properties. Therefore, all marinades are prepared on its basis. Thanks to this, canned vegetables are stored longer without a certain temperature.

Harm

Vinegar is a toxic substance, so consumption in large doses and improperly concentrated amounts can lead to serious problems in the human body. In simple terms, the degree of danger depends on how correctly you separate it from.

The most dangerous solution for humans is the one whose concentration exceeds 30%. If such a solution comes into contact with the mucous membrane and skin, it can cause a severe chemical burn.

The use of vinegar is approved in industry around the world, as it is completely safe when used correctly.

Where else is it used?

It is used not only in the production of various foods, but also in:

• domestic conditions (effectively removes scale inside teapots and cares for work surfaces);
• chemical industries (acts as a solvent and chemical reagent);
• medical field (medicines are made on its basis);
• other areas of industry.

What's the use?

Acetic acid is involved in the breakdown of carbohydrates and carbohydrates that enter the human body along with food.

Daily norm

To date, experts have not determined the daily intake of this food preservative. Despite the fact that it is highly popular in cooking, scientists have not calculated how much a person needs or can consume such a substance.

There have never been cases in medical practice where a person had a deficiency of a substance in the body that led to any serious disorders. But at the same time, there is a certain group of people for whom this preservative is contraindicated. Doctors do not recommend it for patients with inflammation of the gastric mucosa, ulcers and inflammation of the digestive system.

Experts explain this by saying that the preservative can irritate and destroy the gastric mucosa. At best, the patient will only experience heartburn, and at worst, a burn to the digestive system.

In addition, there is another reason why you should abandon such substances - individual intolerance of the body. To avoid such complications, it is better to avoid such foods.

Overdose

Vinegar affects human health in the same way as hydrochloric, sulfuric or nitric acids. The only difference from the above acids is the surface effect.

After scientific experiments, scientists came to the conclusion that the lethal dose for humans is 11 ml. This is approximately one glass of table vinegar or 30 ml of essence.

When vapors of a substance enter the lungs, they can cause serious inflammation of the lung tissue with serious consequences.

Another serious consequence of an overdose is tissue death, complicated cirrhosis, and death of kidney cells.

How does it interact with other substances?

Excellent interaction with proteins was noted, while the body absorbs it more easily.

A similar interaction occurs with carbohydrates. It helps the body more easily absorb meat, fish and vegetable foods.

But remember that such positive aspects are possible only with the proper functioning of the digestive system.

People often use this substance as a basis for preparing medications. It effectively relieves inflammation and lowers body temperature.

The preservative additive with the digital number E260 was officially approved and allowed to be used in the production of various foods throughout the world.

After conducting a large number of experiments and laboratory studies, scientists came to the conclusion that proper use and the permitted dosage do not have a negative effect on the human body.

The body completely absorbs it. This is a kind of intermediate metabolite (a product of the metabolism of any compounds) that performs energetic and structural functions in most metabolic processes. In order not to harm your health, you need to be able to properly dilute E260 with water. A 30% solution poses a great danger to humans. Follow all instructions for use.