Formic acid vapor contains single molecules. Formic acid - application
Methane acid.
Chemical properties
Chemical formula of formic acid: HCOOH. This is one of the first representatives of monobasic carboxylic acids. The substance was first isolated in 1670 from a forest (red) ant. In the natural environment, it is found in bee venom, nettles and needles of conifers, jellyfish secretions, and fruits.
Physical Properties
The racemic formula of methanoic acid is: CH2O2. The substance under normal conditions has the form of a colorless liquid, which is highly soluble in, acetone , toluene And benzene . Molar mass= 46.02 grams per mole. Ethers (ethyl ether and methyl ether) and salts of methane to-you received the name formates .
Chemical properties
According to the structural formula of Formic acid, conclusions can be drawn and its chemical properties. Formic acid can exhibit properties set and some of the properties of aldehydes (reductive reactions).
During the oxidation of formic acid, for example, carbon dioxide is actively released. The substance is used as a preservative agent (code E236). Formic acid interacts with acetic acid (concentrated) and decomposed into carbon monoxide and ordinary water with heat release. Chemical compound reacts with sodium hydroxide . The substance does not interact with hydrochloric acid, silver, sodium sulfate and so on.
Obtaining formic acid
The substance is formed as a by-product during oxidation butane and production acetic acid . It can also be obtained by hydrolysis formamide And methyl formate (with excess water); when CO is hydrated in the presence of some alkali. Qualitative reaction for detection methane acid may serve as a reaction to algedigs . Ammonia can act as an oxidizing agent oxide solution silver and Cu(OH)2. A silver mirror reaction is used.
The use of formic acid
The substance is used as an antibacterial agent and a preservative in the preparation of feed for long-term storage, the agent significantly slows down the processes of decay and decay. The chemical compound is used in the process of dyeing wool; as an insecticide in beekeeping; when carrying out some chemical reactions (acts as a solvent). IN Food Industry the tool is labeled E236. In medicine, acid is used in combination with ("pervomur" or permic acid ) as antiseptic , for the treatment of diseases of the joints.
pharmachologic effect
Local anesthetic, distracting, anti-inflammatory, locally irritating, improving tissue metabolism.
Pharmacodynamics and pharmacokinetics
Methanoic acid, when applied to the surface of the epidermis, irritates the nerve endings of the skin, muscle tissue, activates specific reflex reactions, stimulates the production of neuropeptides And enkephalins . At the same time, it decreases pain sensitivity and increased vascular permeability. The substance stimulates the processes of liberation 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 as part of solutions for the treatment of rheumatic pains, periarthritis , poly- And monoarthritis .
Contraindications
The product should not be used if present, at the site of application, if there are wounds and abrasions on the skin.
Side effects
Methanoic acid can cause local reactions, itching, redness, skin irritation, skin peeling, allergy .
Instructions for use (Method and dosage)
The drug is used topically, in combination with other substances. The drug is applied to the affected area and gently rubbed.
Overdose
There are no data on drug overdose.
Interaction
The medicine is compatible with other drugs.
special instructions
The substance must not be taken orally or applied to the mucous membrane, avoid contact with the eyes.
Formic acid is the simplest representative of organic acids. The areas of application of this substance are really wide: industry, medicine and laboratory conditions. It was first isolated from ants, which is how it got its name. This article describes in detail the current methods of obtaining and areas of use of this compound.
Properties
Formally, this substance is a derivative of methane, therefore, according to IUPAC, its name is methanoic acid. The structural formula of formic acid is as follows: 
Its main properties follow from this formula.
Acid properties
The hydrogen atom of the hydroxyl group is split off quite easily even under the action of not only strong, but also weak bases:
- HCOOH + H 2 O \u003d HCOO - + H 3 O +
- HCOOH + OH - \u003d HCOO - + H 2 O
- HCOOH + NH 3 \u003d HCOO - + NH 4 +
This determines the rather strong acidic properties of this compound - it is the strongest limiting organic acid. This means that it has all the properties characteristic of compounds of this class. It is called formates ("formica" is translated from Latin as "ant").
Reactions on the carboxyl group
Formic acid is also able to enter into esterification reactions - the formation of esters with alcohols: 
Moreover, it is the only substance with a carboxyl group that can add to the double bond, also to form esters: 
But the features of formic acid are not only its acidity. If you look closely at the structure of the molecule, you can see another functional group - carbonyl.
Reactions at the carbonyl group
The carbonyl group is characteristic of aldehydes, which means that the compound in question exhibits the properties of this class of compounds. So, it can be reduced to formaldehyde: 
Or oxidize to unstable carbonic acid, which quickly splits off water and turns into carbon dioxide. 
Both of these reactions only demonstrate the properties of formic acid and do not find real applications, but oxidation with a solution of silver oxide in ammonia can be used to qualitative definition this connection.
Sources
This compound can be obtained either synthetically or by isolating it from natural objects. There are several natural sources:
- for the first time it was isolated during the "distillation" of ant bodies, which is why the name arose.
- Nettle is a plant that contains formic acid (found in nettle hairs).
- Formic acid is found in some quantities in the atmosphere, coming there from plants.
Today, it is unlikely that anyone obtains this compound by distillation of ants, since synthetic methods of obtaining are well developed, and the industry successfully applies them:
- hydrolysis of methyl formate formed by the reaction of carbon monoxide with methanol in the presence of strong foundation gives this substance.
- It is also a by-product in the production of acetic acid by the oxidation of alkanes (vinegar is separated). This method is gradually becoming obsolete, as there are more effective ways receipt.
- In the laboratory, it is possible to obtain it by the reaction of oxalic acid with glycerol used for catalysis at a very high temperature.
Application
This connection is very important in many areas of human activity. Unique properties and pretty simple methods obtaining formic acid make it a useful and accessible reagent. Biological properties formic acid make it possible to use it for medical purposes.
In industry
Formic acid is an excellent antiseptic, which allows it to be used as an antibacterial agent. This property is used, for example, in the food industry or in breeding birds.
Reacts with strong dehydrating agents such as sulfuric acid or phosphorus pentoxide, this substance decomposes with the release of carbon monoxide. Therefore, it is used to obtain a small amount of carbon monoxide in the laboratory.
In medicine
A solution of permic acid is an excellent antiseptic, which is the reason for its use in medicine. It is most widely used in surgery and pharmaceuticals.
Home use is also possible: the substance is a fairly effective remedy for warts.
Before using the connection at home, you must read the instructions and familiarize yourself with the precautions.
Toxicity
This compound has low toxicity, but formic acid poisoning is still possible. In a diluted state, it is not harmful to the skin, and solutions with a concentration of more than 10% can cause significant harm, so if it comes into contact with the skin, the contact point must be quickly treated with a soda solution.
It is excreted quite easily from the body in small quantities, however, there are some special situations. For example, in case of poisoning with methanol, the processing products of which are formaldehyde and formic acid, the optic nerve can be severely damaged, which will lead to deterioration or even loss of vision.
Thus, formic acid is a very important and necessary compound. It finds wide application in many areas of human activity. It is a well-known food additive used as a preservative, and its antiseptic properties have been used in medicine. However, in large quantities it can be harmful to the body, so its use requires caution and accuracy.
Classification
a) By basicity (i.e., the number of carboxyl groups in the molecule):
Monobasic (monocarboxylic) RCOOH; For example:
CH 3 CH 2 CH 2 COOH;
HOOS-CH 2 -COOH propanedioic (malonic) acid
Tribasic (tricarboxylic) R (COOH) 3, etc.
b) According to the structure of the hydrocarbon radical:
Aliphatic
limit; for example: CH 3 CH 2 COOH;
unsaturated; for example: CH 2 \u003d CHCOOH propenoic (acrylic) acid
Alicyclic, for example:
Aromatic, for example:
Limit monocarboxylic acids
(monobasic saturated carboxylic acids) - carboxylic acids in which a saturated hydrocarbon radical is connected to one carboxyl group -COOH. All of them have general formula C n H 2n+1 COOH (n ≥ 0); or CnH 2n O 2 (n≥1)
Nomenclature
Systematic names of monobasic limit carboxylic acids are given by the name of the corresponding alkane with the addition of the suffix -ovaya and the word acid.
1. HCOOH methane (formic) acid
2. CH 3 COOH ethanoic (acetic) acid
3. CH 3 CH 2 COOH propanoic (propionic) acid
isomerism
The isomerism of the skeleton in the hydrocarbon radical is manifested, starting with butanoic acid, which has two isomers:
Interclass isomerism manifests itself, starting with acetic acid:
CH 3 -COOH acetic acid;
H-COO-CH 3 methyl formate (methyl ester of formic acid);
HO-CH 2 -COH hydroxyethanal (hydroxyacetic aldehyde);
HO-CHO-CH 2 hydroxyethylene oxide.
homologous series
Trivial name |
IUPAC name |
|
Formic acid |
Methanoic acid |
|
Acetic acid |
Ethanoic acid |
|
propionic acid |
propanoic acid |
|
Butyric acid |
Butanoic acid |
|
Valeric acid |
Pentanoic acid |
|
Caproic acid |
Hexanoic acid |
|
Enanthic acid |
Heptanoic acid |
|
Caprylic acid |
Octanoic acid |
|
Pelargonic acid |
Nonanoic acid |
|
capric acid |
Decanoic acid |
|
Undecylic acid |
undecanoic acid |
|
Palmitic acid |
Hexadecanic acid |
|
Stearic acid |
Octadecanic acid |
Acid residues and acid radicals
acid residue |
Acid radical (acyl) |
|
UNSD |
NSOO- |
|
CH 3 COOH |
CH 3 SOO- |
|
CH 3 CH 2 COOH |
CH 3 CH 2 COO- |
|
CH 3 (CH 2) 2 COOH |
CH 3 (CH 2) 2 COO- |
|
CH 3 (CH 2) 3 COOH |
CH 3 (CH 2) 3 COO- |
|
CH 3 (CH 2) 4 COOH |
CH 3 (CH 2) 4 COO- |
Electronic structure of carboxylic acid molecules
The shift of the electron density shown in the formula towards the carbonyl oxygen atom causes a strong polarization O-N connections, as a result of which the detachment of the hydrogen atom in the form of a proton is facilitated - in aqueous solutions, the process of acid dissociation occurs:
RCOOH ↔ RCOO - + H +
In the carboxylate ion (RCOO -), p, π-conjugation of the lone pair of electrons of the oxygen atom of the hydroxyl group with p-clouds forming a π-bond takes place, as a result, the π-bond is delocalized and uniform distribution negative charge between two oxygen atoms:
In this regard, for carboxylic acids, in contrast to aldehydes, addition reactions are not characteristic.
Physical Properties
The boiling points of acids are much higher than the boiling points of alcohols and aldehydes with the same number of carbon atoms, which is explained by the formation of cyclic and linear associates between acid molecules due to hydrogen bonds:
Chemical properties
I. Acid properties
The strength of acids decreases in the series:
HCOOH → CH 3 COOH → C 2 H 6 COOH → ...
1. Neutralization reactions
CH 3 COOH + KOH → CH 3 COOK + n 2 O
2. Reactions with basic oxides
2HCOOH + CaO → (HCOO) 2 Ca + H 2 O
3. Reactions with metals
2CH 3 CH 2 COOH + 2Na → 2CH 3 CH 2 COONa + H 2
4. Reactions with salts of weaker acids (including carbonates and bicarbonates)
2CH 3 COOH + Na 2 CO 3 → 2CH 3 COONa + CO 2 + H 2 O
2HCOOH + Mg(HCO 3) 2 → (HCOO) 2 Mg + 2CO 2 + 2H 2 O
(HCOOH + HCO 3 - → HCOO - + CO2 + H2O)
5. Reactions with ammonia
CH 3 COOH + NH 3 → CH 3 COONH 4
II. -OH group substitution
1. Interaction with alcohols (esterification reactions)
2. Interaction with NH 3 when heated (acid amides are formed)
Acid amides 
hydrolyzed to form acids:
or their salts:
3. Formation of acid halides
Acid chlorides are of the greatest importance. Chlorinating reagents - PCl 3 , PCl 5 , thionyl chloride SOCl 2 .
4. Formation of acid anhydrides (intermolecular dehydration)
Acid anhydrides are also formed by the interaction of acid chlorides with anhydrous salts of carboxylic acids; in this case, mixed anhydrides of various acids can be obtained; For example:
III. Substitution reactions of hydrogen atoms at the α-carbon atom
Features of the structure and properties of formic acid
The structure of the molecule
The formic acid molecule, unlike other carboxylic acids, contains an aldehyde group in its structure.
Chemical properties
Formic acid enters into reactions characteristic of both acids and aldehydes. Showing the properties of an aldehyde, it is easily oxidized to carbonic acid:
In particular, HCOOH is oxidized with an ammonia solution of Ag 2 O and copper (II) hydroxide Cu (OH) 2, i.e. gives qualitative reactions for the aldehyde group:
When heated with concentrated H 2 SO 4, formic acid decomposes into carbon monoxide (II) and water:
Formic acid is noticeably stronger than other aliphatic acids, since the carboxyl group in it is bonded to a hydrogen atom, and not to an electron-donating alkyl radical.
Methods for obtaining saturated monocarboxylic acids
1. Oxidation of alcohols and aldehydes
The general scheme for the oxidation of alcohols and aldehydes:
KMnO 4 , K 2 Cr 2 O 7 , HNO 3 and other reagents are used as oxidizers.
For example:
5C 2 H 5 OH + 4KMnO 4 + 6H 2 S0 4 → 5CH 3 COOH + 2K 2 SO 4 + 4MnSO 4 + 11H 2 O
2. Hydrolysis of esters
3. Oxidative cleavage double and triple bonds in alkenes and alkynes
Methods for obtaining HCOOH (specific)
1. Interaction of carbon monoxide (II) with sodium hydroxide
CO + NaOH → HCOONa sodium formate
2HCOONa + H 2 SO 4 → 2HCOOH + Na 2 SO 4
2. Decarboxylation of oxalic acid
Methods for obtaining CH 3 COOH (specific)
1. Catalytic oxidation of butane
2. Synthesis from acetylene
3. Catalytic carbonylation of methanol
4. Acetic acid fermentation of ethanol
This is how food grade acetic acid is obtained.
Obtaining higher carboxylic acids
Hydrolysis of natural fats
Unsaturated monocarboxylic acids
Key Representatives
General formula of alkenoic acids: C n H 2n-1 COOH (n ≥ 2)
CH 2 \u003d CH-COOH propenoic (acrylic) acid
Higher unsaturated acids
The radicals of these acids are part of vegetable oils.
C 17 H 33 COOH - oleic acid, or cis-octadiene-9-oic acid
Trance-isomer of oleic acid is called elaidic acid.
C 17 H 31 COOH - linoleic acid, or cis, cis-octadiene-9,12-oic acid
C 17 H 29 COOH - linolenic acid, or cis, cis, cis-octadecatriene-9,12,15-oic acid
Except common properties carboxylic acids, unsaturated acids are characterized by addition reactions at multiple bonds in the hydrocarbon radical. So, unsaturated acids, like alkenes, are hydrogenated and decolorize bromine water, for example:
Individual representatives of dicarboxylic acids
Limiting dicarboxylic acids HOOC-R-COOH
HOOC-CH 2 -COOH propanedioic (malonic) acid, (salts and esters - malonates)
HOOC-(CH 2) 2 -COOH butadiic (succinic) acid, (salts and esters - succinates)
HOOC-(CH 2) 3 -COOH pentadiic (glutaric) acid, (salts and esters - glutorates)
HOOC-(CH 2) 4 -COOH hexadioic (adipic) acid, (salts and esters - adipinates)
Features of chemical properties
Dicarboxylic acids are in many ways similar to monocarboxylic acids, but are stronger. For example, oxalic acid is almost 200 times stronger than acetic acid.
Dicarboxylic acids behave like dibasic acids and form two series of salts - acidic and medium:
HOOC-COOH + NaOH → HOOC-COONa + H 2 O
HOOC-COOH + 2NaOH → NaOOC-COONa + 2H 2 O
When heated, oxalic and malonic acids are easily decarboxylated:
Formic acid refers to saturated monobasic carboxylic acids.
Formic (otherwise - methane) acid is an uncolored liquid, soluble in benzene, acetone, glycerin and toluene.
As a food additive, formic acid is registered as E236.
The chemical company "Sintez" is the official distributor of BASF for the supply of Formic Acid to Russia.
Properties of formic acid
The properties of formic acid depend on its concentration. So, according to the classification adopted by the European Union, formic acid is considered safe and has an irritating effect at a concentration of up to 10%, a large concentration already has a corrosive effect.
Thus, concentrated formic acid, if it comes into contact with the skin, can cause severe burns and pain.
Also, contact with its concentrated vapors is unsafe, since formic acid, if inhaled, can damage the respiratory tract, as well as the eyes. If accidentally ingested, it leads to the development of severe necrotizing gastroenteritis.
Another property of formic acid is its ability to be quickly excreted by the body without accumulating in it.
Obtaining formic acid
The chemical formula of formic acid is HCOOH.
For the first time, it was possible to isolate it from red forest ants (abdominal glands) by the English naturalist John Rayem in the 17th century. In addition to these insects, from which it got its name, formic acid is naturally found in some plants (nettles, needles), fruits, and also in the caustic secretions of bees.
Formic acid was artificially synthesized only in the 19th century by the French scientist Joseph Gay-Lussac.
The most common method of obtaining formic acid is its isolation as a by-product in the production of acetic acid, which occurs by liquid-phase oxidation of butane.
In addition, obtaining formic acid is possible:
- As a result chemical reaction methanol oxidation;
- Method of decomposition of glycerol esters of oxalic acid.
The use of formic acid in the food industry
In the food industry, formic acid (E236) is mainly used as an additive in the manufacture of canned vegetables. It slows down the development of pathogenic environment and molds in canned and pickled vegetables.
It is also used in the production of soft drinks, as part of fish marinades and other acidic fish products.
In addition, it is often used to disinfect wine and beer barrels.
The use of formic acid in medicine
In medicine, formic acid is used as an antiseptic, cleansing and analgesic, and in some cases as a bactericidal and anti-inflammatory.
The modern pharmacological industry produces formic acid in the form of a 1.4% alcohol solution for external use (in 50 or 100 ml vials). This external drug belongs to the group of drugs with irritant and analgesic properties.
Formic acid, when applied externally, has a distracting effect, and also improves tissue nutrition and causes vasodilation.
An indication for the use of formic acid in the form of an alcoholic solution is:
- Neuralgia;
- Myositis;
- Arthralgia;
- myalgia;
- Nonspecific mono- and polyarthritis.
Contraindications to the use of formic acid are hypersensitivity to the compound and damage to the skin at the site of application.
In addition to the alcohol solution, this acid is used to prepare ointments, for example, Muravita. It is used for the same indications as formic alcohol, as well as in the treatment of:
- Various injuries, bruises, fractures, bruises;
- Varicose veins;
- fungal diseases;
- Acne, blackheads, and also as a skin cleanser.
In folk medicine, due to its analgesic properties, formic acid has long been used to treat:
- Rheumatism;
- gout;
- Radiculitis.
It has been used in formulations that stimulate hair growth and as a remedy for head lice.
