Formic acid plus water. formic acid, its salts and esters

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 condensation of the vapor, Ray received an aqueous solution of the 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 sodium salt) were obtained artificially by the action of carbon monoxide (II) on a moist at 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 carbon dioxide as a result of the oxidation of organic acid (formic) to inorganic (carbonic), which is unstable and decomposes: HCOOH + [O] = HO-CO-OH = CO 2 + H 2 O.

Formic acid is the simplest and yet strongest carboxylic acid, it is ten times stronger than vinegar. 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 salt is solid state, may not be a record holder for density, but it is distinguished by exceptionally high solubility: 0.5 kg (!) of thallium formate can be dissolved in 100 g of water at room temperature. In 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). More high density for a solution of a mixture of thallium formate and thallium malonate - malonic acid salt CH 2 (COOTl) 2.

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 containers for food are disinfected in pairs. food products(including wine barrels), destroy bee mites. A weak aqueous-alcohol solution of formic acid (formic alcohol) is used in medicine for rubbing.

Salt against ants May 8th, 2018

There seemed to be situations when ants really bothered us, but we didn’t really know how to protect ourselves from them. They seem to describe the methods here, but I have never heard of them in my life.

Have you tried any of this?

1. Salt on the doorstep

The easiest and laziest way to repel ants from your home is to sprinkle salt on the threshold. And at the same time, window sills, all passages and places of mass accumulation of many-legged pests.

This method is by no means just another modern life hack. It was first described back in 1937 on the pages of Times magazine. The article, titled “Salt v. Insect,” gave very vague explanations: either the ants must die en masse from thirst (after all, salt absorbs moisture), or from dehydration of their exoskeleton. But since then, more than one generation of people suffering from the ant problem has been actively sprinkling salt on their thresholds. And he claims that it works.

2. Salt and water

Gatherings are planned for fresh air? If you have a table in your yard and ants are actively encroaching on it, prepare four plastic containers. Fill each with water, adding a little salt, and use the containers as “stands” for table legs (as in the photo). Ants will not be able to get through such a “ditch”, and the most stubborn of them will not survive a bath with salt. So insects definitely won’t taste your food.

3. Sugar and boric acid

An effective remedy against ants can be made using not only salt, but also sugar. In a deep container, mix a glass of sugar and a tablespoon of boric acid, carefully and slowly pour in a glass of warm water and wait. The mixture should foam and crystallize slightly.

Now dip several cotton pads into the resulting cocktail and place them in places where you constantly notice ants. Insects will be attracted to such a “delicacy”, and they will even bring its crumbs to their nest. But the ant organism will not withstand such an explosive mixture and in a matter of hours it will finish them off.

sources

Ants bring many benefits to nature. They destroy pests, enrich the soil with potassium and fluorine, and loosen the soil. Therefore, one found in the forest cannot be touched. But garden individuals become enemies of the harvest. Insects acidify the soil too much and... Many people use salt to kill ants in their gardens and apartments. It helps destroy pests quickly and without unnecessary chemicals.

How to use in an apartment

It is not always possible to use it in a closed space. They can be swallowed by a curious baby or pet. And adults are at risk when they use poison. In this case, salt helps. It quickly removes ants from any part of the house.

On a note!

It's better to take the regular one table salt. It's inexpensive and helps a lot.

To force ants to leave human habitation, the garden should use the following recipes:

1. Sprinkle fine salt into cracks, window sills and doors.
2. Mix salt and salt in equal proportions. Treat ant paths with the mixture.
3. Mix the substance with hot pepper. Fall asleep in places where pests accumulate.

The insects prefer to move to a safer place and leave the human home.

How to use in the garden

They cause the most problems. But even here ordinary salt can cope with them.

I don’t touch the ants in the forest, but kill them in the garden with salt. I once read that boiling water helps get rid of them. Regular boiling water didn’t help me, but salty water did. I'm waiting for evening to come and the insects to go to their nest. Then I prepare a strong saline solution, bring it to a boil and pour it on the pests. But this method is not suitable for trees. It helps to wrap the barrel with polyethylene, covered with .

Tamara Lvovna, Moscow

Salt against ants in the garden is used as follows:

1. A thin trail of sweet water flows from the anthill. When the ants begin to run towards, they are sprinkled with the product or trampled under foot. The next day the procedure is repeated.
2. Hot water is poured into the spray bottle salty water and sprayed on pests.
3. The ant nest is filled with table salt.

If you can’t kill insects using these methods, then it’s worth a try.

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 - qualitative reactions 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 the household as a flavoring and preservative substance.

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

Oxalic acid- V metallurgical industry(removal of scale).

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 Food Industry for canning vegetables, mushrooms, 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, flaxseed 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.

Formic acid (E 236, methanoic acid) is in first place among monobasic acids (saturated). IN normal conditions the substance is a colorless liquid. Chemical formula formic acid HCOOH.

Along with its acidic characteristics, it also exhibits aldehyde qualities. This is due to the structure of the substance E236.

In nature, the substance is found in nettles, pine needles, fruits, caustic bees and secretions, and in ants. Formic acid was first discovered and described in the 17th century. The substance got its name because it was found in ants.

The chemical properties of a substance appear depending on the concentration. In accordance with the EU classification, with a quantitative composition of up to 10% it is irritating, and more than 10% is corrosive.

100% formic acid (liquid) in contact with skin provokes very severe burns. Contact of even a small amount of it in such a concentration on the skin causes severe pain. The affected area first begins to turn white, as if covered with frost, then becomes waxy. A red border forms around the burned area. Acid can quickly penetrate the fatty skin layer, so it is necessary to immediately rinse the affected area.

Concentrated vapors of the substance can cause damage to the respiratory tract and eyes. If accidentally ingested, even in diluted form, methanoic acid causes severe necrotic gastroenteritis.

The body quickly processes and eliminates the substance. However, at the same time, E236 and formaldehydes formed during the process provoke lesions that lead to blindness.

Salts of formic acid are called formates. Heating with concentrated water leads to the decomposition of E236 into H2O and CO, which is used to form carbon monoxide.

IN industrial conditions Formic acid is obtained from carbon monoxide.

Substances 100.7, freezing point - 8.25 degrees.

At room conditions, E236 decomposes into water. According to experimental evidence, methanoic acid is stronger than acetic acid. However, due to the ability of the former to rapidly decompose, it is used as a solvent extremely rarely.

It is believed that E236 is a very hygroscopic substance. During the experiments, it was found that obtaining an anhydrous drug using dehydrating reagents is not possible.

Contact of formic acid with moist air is unacceptable.

E236 with a purity of more than 99% can be obtained from an aqueous solution using two-stage distillation using butyric acid. The first distillation eliminates the bulk of the water. The remainder will contain approximately 77% substance. To distill it, 3-6 times the amount is used in the form of an azeotropic mixture.

When opening a container of E236, special care must be taken. When formic acid is stored for an extended period, significant pressure can build up in the container.