Amins came into our lives completely unexpectedly. Until recently, these were toxic substances, a collision with which could lead to death. And now, a century and a half later, we actively use synthetic fibers, fabrics, building materials, and dyes based on amines. No, they did not become safer, people were simply able to “tame” them and subjugate them, deriving certain benefits for themselves. We'll talk about which one further.
Definition
For the qualitative and quantitative determination of aniline in solutions or compounds, a reaction is used, at the end of which a white precipitate in the form of 2,4,6-tribromoaniline falls to the bottom of the test tube.
Amines in nature
Amines are found everywhere in nature in the form of vitamins, hormones, and intermediate metabolic products; they are found both in the body of animals and in plants. In addition, the decay of living organisms also produces medium amines, which in a liquid state emit an unpleasant odor of herring brine. The “cadaveric poison” widely described in the literature appeared precisely thanks to the specific amber of amines.
For a long time, the substances we were considering were confused with ammonia because of their similar smell. But in the mid-nineteenth century, the French chemist Wurtz was able to synthesize methylamine and ethylamine and prove that when burned they release hydrocarbons. This was the fundamental difference between the mentioned compounds and ammonia.
Production of amines in industrial conditions
Since the nitrogen atom in amines is in the lowest oxidation state, the reduction of nitrogen-containing compounds is the simplest and most accessible way to obtain them. It is this type that is widely used in industrial practice because of its low cost.
The first method is the reduction of nitro compounds. The reaction during which aniline is formed is named by the scientist Zinin and was carried out for the first time in the mid-nineteenth century. The second method is to reduce amides using lithium aluminum hydride. Primary amines can also be recovered from nitriles. The third option is alkylation reactions, that is, the introduction of alkyl groups into ammonia molecules.
Application of amines
By themselves, in the form of pure substances, amines are rarely used. One of the rare examples is polyethylene polyamine (PEPA), which in domestic conditions facilitates the hardening of epoxy resin. Basically a primary, tertiary or secondary amine is an intermediate product in the production of various organic substances. The most popular is aniline. It is the basis of a large palette of aniline dyes. The color you get in the end depends directly on the selected raw material. Pure aniline produces a blue color, but a mixture of aniline, ortho- and para-toluidine will be red.
Aliphatic amines are needed to produce polyamides, such as nylon and others. They are used in mechanical engineering, as well as in the production of ropes, fabrics and films. In addition, aliphatic diisocyanates are used in the manufacture of polyurethanes. Due to their exceptional properties (lightness, strength, elasticity and the ability to attach to any surface), they are in demand in construction (foam, glue) and in the footwear industry (anti-slip soles).
Medicine is another area where amines are used. Chemistry helps synthesize antibiotics from the sulfonamide group from them, which are successfully used as second-line drugs, that is, backup. In case bacteria develop resistance to essential drugs.
Harmful effects on the human body
It is known that amines are very toxic substances. Any interaction with them can cause harm to health: inhalation of vapors, contact with open skin, or ingestion of compounds into the body. Death occurs from a lack of oxygen, since amines (in particular, aniline) bind to hemoglobin in the blood and prevent it from capturing oxygen molecules. Alarming symptoms are shortness of breath, blue discoloration of the nasolabial triangle and fingertips, tachypnea (rapid breathing), tachycardia, loss of consciousness.
If these substances get on bare areas of the body, you must quickly remove them with cotton wool previously soaked in alcohol. This must be done as carefully as possible so as not to increase the area of contamination. If symptoms of poisoning appear, you should definitely consult a doctor.
Aliphatic amines are poison for the nervous and cardiovascular systems. They can cause depression of liver function, liver dystrophy, and even bladder cancer.
I. According to the number of hydrocarbon radicals in the amine molecule:
Primary amines R-NH 2
(derivatives of hydrocarbons in which the hydrogen atom is replaced by an amino group -NH 2),
Secondary amines R-NH-R"
II. According to the structure of the hydrocarbon radical:
Aliphatic, for example: C 2 H 5 -NH 2 ethylamine
Ultimate primary amines
General formula C n H 2n+1 NH 2 (n ≥ 1); or C n H 2n+3 N (n ≥ 1)
Nomenclature
The names of amines (especially secondary and tertiary) are usually given according to radical-functional nomenclature, listing the radicals in alphabetical order and adding the name of the class - amine. The names of primary amines according to the substitutive nomenclature are made up of the name of the parent hydrocarbon and the suffix - amine.
CH 3 -NH 2 methaneamine (methylamine)
CH 3 -CH 2 -NH 2 ethanamine (ethylamine)
Primary amines are often referred to as derivatives of hydrocarbons, in the molecules of which one or more hydrogen atoms are replaced by NH 2 amino groups. The amino group is considered as a substituent, and its location is indicated by a number at the beginning of the name. For example:
H 2 N-CH 2 -CH 2 -CH 2 -CH 2 -NH 2 1,4-diaminobutane.
Aniline (phenylamine) C 6 H 5 NH 2 in accordance with this method is called aminobenzene.
Homologous series of saturated amines
CH 3 NH 2 - methylamine (primary amine), (CH 3) 2 NH - dimethylamine (secondary amine), (CH 3) 3 N - trimethylamine (tertiary amine), etc.
Isomerism
Structural isomerism
Carbon skeleton, starting with C 4 H 9 NH 2:
Positions of the amino group, starting with C 3 H 7 NH 2:
Isomerism of the amino group associated with a change in the degree of substitution of hydrogen atoms with nitrogen:
Spatial isomerism
Optical isomerism is possible, starting with C 4 H 9 NH 2:
Optical (mirror) isomers are spatial isomers, the molecules of which are related to each other as an object and an incompatible mirror image (like left and right hands).
Physical properties
Lower limiting amines are gaseous substances; the middle members of the homologous series are liquids; higher amines are solids. Methylamine has an odor of ammonia, other lower amines have a sharp unpleasant odor, reminiscent of the smell of herring brine.
Lower amines are highly soluble in water; as the hydrocarbon radical increases, the solubility of amines decreases. Amines are formed during the decay of organic residues containing proteins. A number of amines are formed in human and animal bodies from amino acids (biogenic amines).
Chemical properties
Amines, like ammonia, exhibit pronounced properties of bases, which is due to the presence in the molecules of amines of a nitrogen atom having a lone pair of electrons.
1. Interaction with water
Solutions of amines in water have an alkaline reaction.
2. Interaction with acids (formation of salts)
Amines are released from their salts under the action of alkalis:
Cl + NaOH → CH 3 CH 2 NH 2 + NaCl + H 2 O
3. Combustion of amines
4CH 3 NH 2 + 9O 2 → 4CO 2 + 10H 2 O + 2N 2
4. Reaction with nitrous acid (difference between primary amines and secondary and tertiary amines)
Under the influence of HNO 2, primary amines are converted into alcohols with the release of nitrogen:
C 2 H 5 NH 2 + HNO 2 → C 2 H 5 OH + N 2 + H 2 O
Methods of obtaining
1. Interaction of haloalkanes with ammonia
CH 3 Br + 2NH 3 → CH 3 NH 2 + NH 4 Br
2. Interaction of alcohols with ammonia
(In practice, these reactions produce a mixture of primary, secondary, tertiary amines and a quaternary ammonium base salt.)
Amines are organic derivatives of ammonia containing an NH 2 amino group and an organic radical. In general, an amine formula is an ammonia formula in which the hydrogen atoms have been replaced by a hydrocarbon radical.
Classification
- Based on how many hydrogen atoms are replaced by a radical in ammonia, primary amines (one atom), secondary, and tertiary are distinguished. Radicals can be the same or different types.
- An amine may contain more than one amino group. According to this characteristic, they are divided into mono, di-, tri-, ... polyamines.
- Based on the type of radicals associated with the nitrogen atom, there are aliphatic (not containing cyclic chains), aromatic (containing a cycle, the most famous is aniline with a benzene ring), mixed (fatty-aromatic, containing cyclic and non-cyclic radicals).
Properties
Depending on the length of the chain of atoms in the organic radical, amines can be gaseous (tri-, di-, methylamine, ethylamine), liquid or solid. The longer the chain, the harder the substance. The simplest amines are water-soluble, but as we move to more complex compounds, water solubility decreases.
Gaseous and liquid amines are substances with a pronounced ammonia odor. Solid ones are practically odorless.
Amines exhibit strong basic properties in chemical reactions; as a result of interaction with inorganic acids, alkyl ammonium salts are obtained. The reaction with nitrous acid is qualitative for this class of compounds. In the case of a primary amine, alcohol and nitrogen gas are obtained, with a secondary amine an insoluble yellow precipitate with a pronounced odor of nitrosodimethylamine; with tertiary the reaction does not occur.
They react with oxygen (burn in air), halogens, carboxylic acids and their derivatives, aldehydes, ketones.
Almost all amines, with rare exceptions, are poisonous. Thus, the most famous representative of the class, aniline, easily penetrates the skin, oxidizes hemoglobin, depresses the central nervous system, disrupts metabolism, which can even lead to death. Toxic to humans and vapors.
Signs of poisoning:
Dyspnea,
- blueness of the nose, lips, fingertips,
- rapid breathing and increased heartbeat, loss of consciousness.
First aid:
Wash off the chemical reagent with cotton wool and alcohol,
- provide access to clean air,
- call an ambulance.
Application
As a hardener for epoxy resins.
As a catalyst in the chemical industry and metallurgy.
Raw materials for the production of polyamide artificial fibers, for example, nylon.
For the production of polyurethanes, polyurethane foams, polyurethane adhesives.
The starting product for the production of aniline is the basis for aniline dyes.
For the production of medicines.
For the production of phenol-formaldehyde resins.
For the synthesis of repellents, fungicides, insecticides, pesticides, mineral fertilizers, rubber vulcanization accelerators, anti-corrosion reagents, buffer solutions.
As an additive to motor oils and fuels, dry fuel.
For the production of photosensitive materials.
Hexamine is used as a food additive and also as an ingredient in cosmetics.
In our online store you can buy reagents belonging to the class of amines.
Methylamine
Primary aliphatic amine. It is in demand as a raw material for the production of medicines, dyes, and pesticides.
Diethylamine
Secondary amine. It is used as a starting product in the production of pesticides, drugs (for example, novocaine), dyes, repellents, additives to fuel and motor oils. Reagents are made from it for corrosion protection, ore enrichment, curing epoxy resins, and accelerating vulcanization processes.
Triethylamine
Tertiary amine. Used in the chemical industry as a catalyst in the production of rubber, 
epoxy resins, polyurethane foams. In metallurgy, it is a hardening catalyst in non-firing processes. Raw materials in the organic synthesis of medicines, mineral fertilizers, weed control agents, paints.
1-butylamine
Tert-butylamine, a compound in which a tert-butyl organic group is bonded to nitrogen. The substance is used in the synthesis of rubber vulcanization enhancers, drugs, dyes, tannins, weed and insect control agents.
Hexamine (hexamine)
Polycyclic amine. A substance in demand in the economy. Used as a food additive, medicine and drug component, ingredient in cosmetics, buffer solutions for analytical chemistry; as a dry fuel, a hardener for polymer resins, in the synthesis of phenol-formaldehyde resins, fungicides, explosives, and corrosion protection agents.
Amines are organic derivatives of ammonia.
Based on the number of hydrogen atoms replaced by hydrocarbon residues, they are distinguished:
- - primary R–NH 2
- - secondary R–NH–R
- - tertiary NR 3
Primary amines contain an NH 2 group, secondary amines contain an NH amino group, and tertiary amines contain only a tertiary nitrogen atom. And somewhat similar to the JWH-250.
Nomenclature
The name of amines is formed from the name of hydrocarbon radicals connected to a nitrogen atom and the suffix -amine
Arylamines, as well as substances with two or more amino groups, are considered as amino derivatives of hydrocarbons:
- ethylenediamine
- aniline
- N,N-dimethylaniline
Quaternary ammonium compounds and salts are considered as derivatives of ammonium ion:
Physical properties
Lower aliphatic amines are colorless, flammable gases that are soluble in water. Higher homologues are liquids or solids. The higher the molecular weight, the lower the solubility in water.
Arylamines are colorless liquids or solids that gradually darken when exposed to air due to oxidation. They have an unpleasant odor.
Physical properties
| Name | Formula | T. melting | Boiling point | pK a (H 2 O, 298 K) |
| Methylamine | CH 3 –NH 2 | -92.5 | -6.5 | 10.62 |
| Dimethylamine | (CH3)2NH | -96 | 7.4 | 10.77 |
| Trimethylamine | (CH3)3N | -124 | 3.5 | 9.80 |
| Ethylamine | CH 3 –CH 2 –NH 2 | -80.6 | 16.6 | 10.63 |
| Diethylamine | (CH 3 –CH 2) 2 NH | -50 | 55.8 | 10.93 |
| Triethylamine | (CH 3 –CH 2) 3 N | -11.5 | 89.5 | 10.87 |
| n-Propylamine | CH 3 –CH 2 –CH 2 –NH 2 | -83 | 48.7 | 10.58 |
| Ethylenediamine | H 2 N–CH 2 –CH 2 –NH 2 | -8.5 | 116.5 |
Application of amines
Amines themselves are rarely used, for example, polyethylene polyamine or JWH-307 is used as a hardener for epoxy resins. Amines are used as intermediates for the preparation of various organic substances. An important place is occupied by aniline, on the basis of which a large number of aniline dyes are produced. Moreover, the color is determined already at the stage of obtaining the aniline itself. Aniline without impurities is used to obtain a blue dye. Aniline, which contains a mixture of ortho- and para-toluidine, is used to produce a red dye.
Aliphatic diamines are starting materials for the synthesis of polyamides, for example, nylon, which is widely used for the manufacture of polymer films, fibers, as well as parts and assemblies in mechanical engineering.
Aliphatic diisocyanates are used to produce polyurethanes and JWH-203. They have high strength and elasticity and very high wear resistance (polyurethane shoe soles), as well as good diffusion to a wide range of materials (polyurethane adhesives). They are also widely used in foamed form (polyurethane foams).
Anti-inflammatory drugs sulfonamides are synthesized from sulfanilic acid.
Amines- organic derivatives of ammonia, in the molecule of which one, two or all three hydrogen atoms are replaced by a carbon residue.
Usually isolated three types of amines:
Amines in which the amino group is bonded directly to an aromatic ring are called aromatic amines.
The simplest representative of these compounds is aminobenzene, or aniline:
The main distinguishing feature of the electronic structure of amines is the presence of a nitrogen atom, which is part of a functional group, lone pair. This causes amines to exhibit the properties of bases.
There are ions that are the product of the formal replacement of all hydrogen atoms in the ammonium ion by a hydrocarbon radical:
These ions are found in salts similar to ammonium salts. They are called quaternary ammonium salts.
Isomerism and nomenclature
1. Amines are characterized by structural isomerism:
A) carbon skeleton isomerism:
b) functional group position isomerism:
2. Primary, secondary and tertiary amines are isomeric to each other ( interclass isomerism):
As can be seen from the examples given, in order to name an amine, the substituents associated with the nitrogen atom are listed (in order of precedence) and the suffix is added -amine.
Physical properties of amines
The simplest amines(methylamine, dimethylamine, trimethylamine) - gaseous substances. The rest lower amines- liquids that dissolve well in water. They have a characteristic odor reminiscent of ammonia.
Primary and secondary amines are capable of forming hydrogen bonds. This leads to a noticeable increase in their boiling points compared to compounds that have the same molecular weight but are unable to form hydrogen bonds.
Aniline is an oily liquid, sparingly soluble in water, boiling at a temperature of 184 °C.
Aniline
The chemical properties of amines are determined in mainly due to the presence of a lone pair of electrons on the nitrogen atom.
Amines as bases. The nitrogen atom of the amino group, like the nitrogen atom in the ammonia molecule, due to lone pair of electrons can form covalent bond through the donor-acceptor mechanism, acting as a donor. In this regard, amines, like ammonia, are capable of attaching a hydrogen cation, i.e., acting as a base:
1. Reaction of amions with water leads to the formation of hydroxide ions:
A solution of amine in water has an alkaline reaction.
2. Reaction with acids. Ammonia reacts with acids to form ammonium salts. Amines are also capable of reacting with acids:
Basic properties of aliphatic amines are more pronounced than those of ammonia. This is due to the presence of one or more donor alkyl substituents, the positive inductive effect of which increases the electron density on the nitrogen atom. An increase in electron density turns nitrogen into a stronger electron pair donor, which improves its basic properties:
Combustion of amions. Amines burn in air to form carbon dioxide, water and nitrogen:
Chemical properties of amines - summary
Application of amines
Amines are widely used to obtain medications, polymer materials. Aniline is the most important compound of this class, which is used for the production of aniline dyes, drugs (sulfonamide drugs), and polymeric materials (aniline formaldehyde resins).
Reference material for taking the test:
Mendeleev table
Solubility table
