In 1670, the English botanist and zoologist John Ray (1627-1705) conducted an unusual experiment. He placed red forest ants in a vessel, poured in water, heated it to a boil and passed a stream of hot steam through the vessel. This process is called steam distillation by chemists and is widely used to isolate and purify many organic compounds. After the steam condensed, Rey obtained an aqueous solution of a new chemical compound. It exhibited, and therefore was called formic acid (the modern name is methane). The names of salts and esters of methane acid - formates - are also associated with ants (Latin formica - “ant”).

Subsequently, entomologists - insect specialists (from the Greek “entokon” - “insect” and “logos” - “teaching”, “word”) determined that females and working ants have poisonous glands in their abdomens that produce acid. The forest ant has approximately 5 mg. Acid serves as an insect weapon for defense and attack. There is hardly a person who has not experienced their bites. The sensation is very reminiscent of a nettle burn, because formic acid is also contained in the finest hairs of this plant. Sticking into the skin, they break off, and their contents burn painfully.

Formic acid is also found in bee venom, pine needles, silkworm caterpillars, and in small quantities it is found in various fruits, organs, tissues, and animal and human secretions. In the 19th century formic acid (in the form of sodium salt) was obtained artificially by the action of carbon monoxide (II) on wet elevated temperature: NaOH + CO = HCOONa. Conversely, under the influence of concentrated formic acid, it decomposes with the release of gas: HCOOH = CO + H 2 O. This reaction is used in the laboratory to obtain pure. When the sodium salt is heated strongly formic acid- sodium formate - a completely different reaction occurs: the carbon atoms of two acid molecules seem to be cross-linked and sodium oxalate is formed - a salt of oxalic acid: 2HCOONa = NaOOC-COONa + H 2.

An important difference between formic acid and others is that it, like a two-faced Janus, has both the properties of both an acid and a a carbon atom that is part of the aldehyde group H-CO-. Therefore, formic acid reduces silver from its solutions - it gives a “silver mirror” reaction, which is characteristic of aldehydes, but not characteristic of acids. In the case of formic acid, this reaction, which is also unusual, is accompanied by the release of carbon dioxide as a result of the oxidation of organic acid (formic) to inorganic acid (carbonic), which is unstable and decomposes: HCOOH + [O] = HO-CO-OH = CO 2 + H 2 O.

Formic acid is the simplest and at the same time the strongest carboxylic acid; it is ten times stronger than acetic acid. When the German chemist Justus Liebig first obtained anhydrous formic acid, it turned out that this was a very dangerous compound. When it comes into contact with the skin, it not only burns, but also literally dissolves it, leaving wounds that are difficult to heal. As Liebig's collaborator Karl Vogt (1817-1895) recalled, he had a scar on his hand for the rest of his life - the result of an “experiment” conducted jointly with Liebig. And it is not surprising - it was later discovered that anhydrous formic acid even dissolves nylon, nylon and other polymers that do not take diluted solutions of other acids and alkalis.

Formic acid found an unexpected application in the production of so-called heavy liquids - aqueous solutions in which even stones do not sink. Geologists need such liquids to separate minerals by density. By dissolving the metal in a 90% solution of formic acid, thallium formate HCOOTl is obtained. This solid salt may not hold a record for density, but it is distinguished by exceptionally high solubility: in 100 g of water at room temperature you can dissolve 0.5 kg (!) of thallium formate. For a saturated aqueous solution, the density varies from 3.40 g/cm 3 (at 20 o C) to 4.76 g/cm 3 (at 90 o C). The solution of a mixture of thallium formate and thallium malonate, the salt of malonic acid CH 2 (COOTl) 2, has an even greater density.

When these are dissolved (in a 1:1 ratio by weight) in minimum quantity water, a liquid with a unique density is formed: 4.324 g/cm 3 at 20 o C, and at 95 o C the density of the solution can be increased to 5.0 g/cm 3. Barite (heavy spar), quartz, corundum, malachite and even granite float in such a solution!

Formic acid has strong bactericidal properties. Therefore, its aqueous solutions are used as a food preservative, and in pairs they disinfect food containers (including wine barrels) and destroy bee mites. A weak aqueous-alcohol solution of formic acid (formic alcohol) is used in medicine for rubbing.

Formic acid is more effective than other means in removing ice from runways and roadways without harming the environment.

Nature as the largest producer

Ants and jellyfish use this substance for their own protection and for obtaining food. Many have repeatedly experienced its effect on own experience accidentally touching nettle leaves. It's about about formic acid, a pungent, odorous liquid of natural origin that has attracted the attention of people for several centuries.

This simplest carboxylic acid was first isolated in its pure form by the English naturalist John Ray in 1671. He placed red forest ants in a glass flask with water, brought the vessel to a boil, and in the resulting distillate he discovered an acidic liquid, which he called formic acid. The first successful laboratory synthesis of this substance dates back to 1855. It was carried out French chemist Marcelin Berthelot. BASF began to show interest in formic acid in the 1920s and began large-scale production in 1935, after the product became in demand in many industries.

Currently, formic acid is a widely used chemical. Dr. Tatiana Levy, innovation manager at BASF Intermediates, calls it “a truly versatile product.” For several decades, formic acid has been successfully used in the most different areas. Thus, it is used in the manufacture of animal feed (as a preservative), in leather and textile production, and also as a component of drilling fluids in the development of oil fields. “In addition, in close cooperation with customers, we are constantly finding new applications for formic acid,” adds Dr. Levy.

Formic acid salts

Formates, used as reagents for removing ice and snow in winter, are more expensive than salts and anti-slip agents (pea gravel or sand). However, the difference becomes less significant when all subsequent costs are taken into account. So, salt (sodium chloride) disrupts water regime and balance nutrients in the soil, and also leads to corrosion of structural elements of buildings, road surfaces and bridges. The effectiveness of anti-slip agents is controversial, as they pollute urban environments and are labor-intensive to clean up. On the contrary, formic acid salts are environmentally friendly and have low corrosive activity; they reliably protect roads and sidewalks from snow and ice (without unwanted side effects). At the same time, there is no need for additional costs associated with replanting trees and shrubs, as well as repairing buildings.

Treating the airport area using formates

European airports combat icing with chemicals. “Salts of formic acid within ten s extra years are used to remove ice from airport runways and taxiways,” explains Dr. Levy. The addition of these salts, also known as formates, ensures that water does not freeze when the temperature drops to 0°C. Depending on the concentration of the deicer, the freezing point can be brought to −50 o C, which differs significantly from the ambient temperature. Accordingly, formates quickly remove thin ice and effectively prevent snow deposition and the formation of new ice on runways. Moreover, these substances do not pose a danger to the environment. “Salts of formic acid together with melt water can end up in drains, but the harm from them (compared to other deicers) can be minimal - due to the ability of formates to biodegrade, during which a very small amount of oxygen is consumed,” emphasizes Tatyana Levi.

The snow removal service at Zurich Airport has been using formates since 2005. “We have very high expectations for reliable, environmentally friendly deicers,” explains Hans-Peter Moll, responsible for airfield maintenance at Zurich Airport. – It is necessary that these compounds quickly react with ice on runways and taxiways, have a long service life, combine well with other materials and remain harmless. Our experience shows that formic acid salts are superior to any other deicer based on these criteria.”

Municipal services are showing growing interest in formates

The positive experience of airports in using formates as alternative deicers has aroused the interest of municipal authorities. Snow removal services in Scandinavia, Switzerland and Austria use these chemicals to remove ice from roadways, bike paths and sidewalks where extra care is required (for example, tree-lined boulevards or historic areas). In Basel, snow has been removed from the artificial surfaces of sports arenas in a similar manner for many years. In this case, first the cleaning is done mechanically, and then the thin remaining layer of snow is melted using formates. Thanks to their effective anti-icing effect, it is possible to quickly bring sites into a condition suitable for sports competitions. “We were very impressed by the ability of formic acid salts to biodegrade when low temperatures. Thus, they do not create obstacles for athletes during competitions. In addition, artificial surfaces and Sports Equipment(balls, rackets, bars, nets) suffer less damage and are better preserved during the winter period when formates are used to remove snow and ice,” summarizes Eric Hardman, responsible for the condition of sports facilities in Basel.

It is worth noting that the absolute leader in the production of formic acid is precisely animals and plants, which together produce larger quantities of this substance than all chemical industry enterprises combined.

Methane boiler.

Chemical properties

Chemical formula of formic acid: HCOOH. This is one of the first representatives of single-base carbon compounds. The substance was first isolated in 1670 from the forest (red) ant. IN natural environment found in bee venom, nettles and needles coniferous trees, jellyfish secretions, fruits.

Physical properties

Racemic formula of methanoic acid: CH2O2. Substance at normal conditions has the appearance of a colorless liquid that is highly soluble in, acetone , toluene And benzene . Molar mass = 46.02 grams per mole. Esters (ethyl ether and methyl ether) and methane salts are called formates .

Chemical properties

Based on the structural formula of Formic acid, we can draw conclusions about its chemical properties. Formic acid is capable of exhibiting properties of the kit and some of the properties of aldehydes (reduction reactions).

When formic acid is oxidized, for example, carbon dioxide is actively released. The substance is used as a preservative agent (code E236). Formic acid reacts with acetic acid (concentrated) and decomposes into carbon monoxide and ordinary water with the release of heat. A chemical compound reacts with sodium hydroxide . The substance does not interact with hydrochloric acid, silver, sodium sulfate and so on.

Preparation of formic acid

The substance is formed as a by-product during oxidation butane and production vinegar . It can also be obtained by hydrolysis formamide And methyl formate (with excess water); during the hydration of CO in the presence of any alkali. Qualitative reaction for detection methanoic acid may be a reaction to algedigs . The role of an oxidizing agent can be ammonia solution of silver oxide and Cu(OH)2. The silver mirror reaction is used.

Applications of formic acid

The substance is used as an antibacterial agent and preservative when preparing feed for long-term storage; the product significantly slows down the processes of decay and rotting. The chemical compound is used in the process of dyeing wool; as an insecticide in beekeeping; during certain chemical reactions (acts as a solvent). In the food industry, the product is labeled E236. In medicine, acid is used in combination with (“pervomur” or performic acid ) as antiseptic , for the treatment of joint diseases.

pharmachologic effect

Local anesthetic, distracting, anti-inflammatory, local irritating, improving tissue metabolism.

Pharmacodynamics and pharmacokinetics

Methane acid, when applied to the surface of the epidermis, irritates the nerve endings of the skin and muscle tissue, activates specific reflex reactions, stimulates the production neuropeptides And enkephalins . This reduces pain sensitivity and increases vascular permeability. The substance stimulates liberation processes kinins And histamine , dilates blood vessels, stimulates immunological processes.

Indications for use

The drug is used to treat instruments and equipment before surgery. The substance is used topically in solutions for the treatment of rheumatic pain, periarthritis , poly- And monoarthritis .

Contraindications

The product should not be used if it is present, at the site of application, or if there are wounds or abrasions on the skin.

Preparation of carboxylic acids

I. In industry

1. Isolated from natural products

(fats, waxes, essential and vegetable oils)

2. Oxidation of alkanes:

2CH 4 + + 3O 2 t,kat→ 2HCOOH + 2H 2 O

methaneformic acid

2CH 3 -CH 2 -CH 2 -CH 3 + 5O 2 t,kat,p→4CH 3 COOH + 2H 2 O

n-butaneacetic acid

3. Oxidation of alkenes:

CH 2 =CH 2 + O 2 t,kat→CH3COOH

ethylene

WITH H 3 -CH=CH 2 + 4[O] t,kat→ CH 3 COOH + HCOOH (acetic acid + formic acid )

4. Oxidation of benzene homologues (production of benzoic acid):

C 6 H 5 -C n H 2n+1 + 3n[O] KMnO4,H+→ C 6 H 5 -COOH + (n-1)CO 2 + nH 2 O

5C 6 H 5 -CH 3 + 6KMnO 4 + 9H 2 SO 4 → 5C 6 H 5 -COOH + 3K 2 SO 4 + 6MnSO 4 + 14H 2 O

toluenebenzoic acid

5.Obtaining formic acid:

Stage 1: CO+NaOH t , p→HCOONa (sodium formate – salt )

2 stage: HCOONa + H 2 SO 4 → HCOOH + NaHSO 4

6. Preparation of acetic acid:

CH3OH+CO t,p→CH3COOH

Methanol

II. In the laboratory

1. Hydrolysis of esters:

2. From salts of carboxylic acids :

R-COONa + HCl → R-COOH + NaCl

3. Dissolving carboxylic acid anhydrides in water:

(R-CO) 2 O + H 2 O → 2 R-COOH

4. Alkaline hydrolysis of halogen derivatives of carboxylic acids:

III. General methods for preparing carboxylic acids

1. Oxidation of aldehydes:

R-COH + [O] → R-COOH

For example, the “Silver Mirror” reaction or oxidation with copper (II) hydroxide are qualitative reactions of aldehydes

2. Oxidation of alcohols:

R-CH 2 -OH + 2[O] t,kat→ R-COOH + H 2 O

3. Hydrolysis of halogenated hydrocarbons containing three halogen atoms per carbon atom.

4. From cyanides (nitriles) - the method allows you to increase the carbon chain:

WITH H 3 -Br + Na-C≡N → CH 3 -CN + NaBr

CH3-CN - methyl cyanide (acetic acid nitrile)

WITH H 3 -CN + 2H 2 O t→ CH 3 COONH 4

acetate ammonium

CH 3 COONH 4 + HCl → CH 3 COOH + NH 4 Cl

5. Usage reagent Grignard

R-MgBr + CO 2 →R-COO-MgBr H2O→ R-COOH + Mg(OH)Br

APPLICATION OF CARBOXYLIC ACIDS

Formic acid– in medicine - formic alcohol (1.25% alcohol solution of formic acid), in beekeeping, in organic synthesis, in the production of solvents and preservatives; as a strong reducing agent.

Acetic acid– in the food and chemical industries (production of cellulose acetate, from which acetate fiber, organic glass, film are produced; for the synthesis of dyes, medicines and esters). IN household as a flavoring and preservative substance.

Butyric acid– for the production of flavoring additives, plasticizers and flotation reagents.

Oxalic acid– in the metallurgical industry (descaling).

Stearic C17H35COOH and palmitic acid C 15 H 31 COOH – as surfactants, lubricants in metalworking.

Oleic acid C 17 H 33 COOH is a flotation reagent and collector for the enrichment of non-ferrous metal ores.

Individual representatives

monobasic saturated carboxylic acids

Formic acid was first isolated in the 17th century from red forest ants. Also found in stinging nettle juice. Anhydrous formic acid is a colorless liquid with a pungent odor and pungent taste that causes burns on the skin. It is used in the textile industry as a mordant for dyeing fabrics, for tanning leather, and also for various syntheses.
Acetic acid widespread in nature - found in animal excretions (urine, bile, feces), in plants (in green leaves). It is formed during fermentation, rotting, souring of wine, beer, and is found in sour milk and cheese. The melting point of anhydrous acetic acid is + 16.5°C, its crystals are transparent as ice, which is why it is called glacial acetic acid. It was first obtained at the end of the 18th century by the Russian scientist T. E. Lovitz. Natural vinegar contains about 5% acetic acid. Vinegar essence is prepared from it, used in the food industry for preserving vegetables, mushrooms, and fish. Acetic acid is widely used in the chemical industry for various syntheses.

Representatives of aromatic and unsaturated carboxylic acids

Benzoic acid C 6 H 5 COOH is the most important representative of aromatic acids. Distributed in nature in flora: in balms, incense, essential oils. In animal organisms it is found in the breakdown products of protein substances. This crystalline substance, melting point 122°C, easily sublimes. IN cold water does not dissolve well. It dissolves well in alcohol and ether.

Unsaturated unsaturated acids with one double bond in the molecule have the general formula C n H 2 n -1 COOH.

High molecular weight unsaturated acids often mentioned by nutritionists (they call them unsaturated). The most common of them is oleic CH 3 –(CH 2) 7 –CH=CH–(CH 2) 7 –COOH or C 17 H 33 COOH. It is a colorless liquid that hardens in the cold.
Polyunsaturated acids with several double bonds are especially important: linoleic CH 3 –(CH 2) 4 –(CH=CH–CH 2) 2 –(CH 2) 6 –COOH or C 17 H 31 COOH with two double bonds, linolenic CH 3 –CH 2 –(CH=CH–CH 2) 3 –(CH 2) 6 –COOH or C 17 H 29 COOH with three double bonds and arachidonic CH 3 –(CH 2) 4 –(CH=CH–CH 2) 4 –(CH 2) 2 –COOH with four double bonds; they are often called essential fatty acids. It is these acids that have the greatest biological activity: they participate in the transfer and metabolism of cholesterol, the synthesis of prostaglandins and other vital substances, and maintain the structure cell membranes, are necessary for the functioning of the visual apparatus and nervous system, affect the immune system. The absence of these acids in food inhibits the growth of animals, inhibits their reproductive function, and causes various diseases. The human body cannot synthesize linoleic and linolenic acids itself and must receive them ready-made with food (like vitamins). For the synthesis of arachidonic acid in the body, linoleic acid is necessary. Polyunsaturated fatty acids with 18 carbon atoms in the form of glycerol esters are found in the so-called drying oils - flaxseed, hemp, poppy, etc. Linoleic acid C17H31COOH and linolenic acid C 17 H 29 COOH are part of vegetable oils. For example, linseed oil contains about 25% linoleic acid and up to 58% linolenic acid.

Sorbic acid (2,4-hexadienoic) acid CH 3 –CH=CH–CH=CHCOOH was obtained from rowan berries (sorbus in Latin). This acid is an excellent preservative, so rowan berries do not become moldy.

The simplest unsaturated acid, acrylic CH 2 = CHCOOH, has a pungent odor (in Latin acris - pungent, pungent). Acrylates (esters of acrylic acid) are used to produce organic glass, and its nitrile (acrylonitrile) is used to produce synthetic fibers.

When naming newly isolated acids, chemists often give free rein to their imagination. Thus, the name of the closest homolog of acrylic acid, croton

CH 3 – CH = CH – COOH, does not come from a mole at all, but from a plant Croton tiglium, from whose oil it was isolated. The synthetic isomer of crotonic acid is very important - methacrylic acid CH 2 = C (CH 3) – COOH, from the ester of which (methyl methacrylate), as well as from methyl acrylate, transparent plastic is made - plexiglass.

Unsaturated carbon acids are capable of addition reactions:

CH 2 = CH-COOH + H 2 → CH 3 -CH 2 -COOH

CH 2 =CH-COOH + Cl 2 → CH 2 Cl -CHCl -COOH

VIDEO:

CH 2 =CH-COOH + HCl → CH 2 Cl -CH 2 -COOH

CH 2 = CH-COOH + H 2 O → HO-CH 2 -CH 2 -COOH

The last two reactions proceed against Markovnikov's rule.

Unsaturated carboxylic acids and their derivatives are capable of polymerization reactions.

Thanks to your beneficial properties formic acid today is one of the most popular chemical substances. This universal product is used in various industries.

Salts of formic acid obtained by the reaction of carbonates, oxides and hydroxides of metals with acid are called formates. The most widely used are potassium, calcium and sodium formates.

Potassium formate

The potassium salt of formic acid is obtained by saponification of formamide. In our country it is allowed to be added to alcoholic drinks and food products as a preservative and salt substitute. It has an antimicrobial effect in an acidic environment, so it was previously used in canning using marinades. But in Lately replaced by safer substances. Also applicable:

• in the production of cosmetics;
• as a tanning agent in tanning;
• as a coolant in refrigeration units;
• as an anti-frost additive in concrete;
• as part of drilling fluids.

Calcium formate

Calcium salt is obtained by reacting formic acid with calcium or its oxide. When working with it, it is necessary to take appropriate precautions, since the substance belongs to the third hazard class. In the Russian Federation it is allowed to be used instead of salt in dietary products and as a preservative for addition to soft drinks in limited quantities. For the production of cosmetics, special bioadditives based on it are often used. In addition, the following applies:

• for tanning leather;
• when dyeing fabrics;
• for printing colored wallpaper;
• for rapid hardening of building mixtures.

Sodium formate

Sodium formic acid is a by-product of the production of pentaerythritol. Used in three ways:

• in the food industry;
• in construction;
• in public utilities.

Preservative E237

This name is adopted for sodium formate in international system classification of food additives. Use as a preservative is due to its pronounced antimicrobial properties. Until recently, this food additive was widespread throughout the world, but due to negative influence on the human body due to overuse, it was banned in many countries. Our country has established clear rules to limit the use of the E237 additive in food products. And to ensure the safety of workers at industrial enterprises, they are prescribed special clothing that insulates the surface of the body and respiratory organs from contact with a substance belonging to hazard class 4.

Antifreeze additive

In order for concrete mixtures to be used in winter construction, care must be taken to ensure that they do not harden in the cold. Sodium formate slows down the freezing process of water in the solution. To avoid the appearance of internal stress caused by the use of an anti-freeze additive, its dosage and method of application are selected in strict accordance with the technology.

Road cleaning

IN last years Formates are used to remove snow and ice from roads. Regular salt promotes corrosion and negatively affects environment. Sodium formate is less corrosive and provides reliable protection against snow and ice without negative effects. Its use allows not only to remove ice, but also to prevent the new formation of ice cover. Therefore, municipal services are increasingly using it as a harmless and effective deicer.