Amines dissolve in water. Amines - concept, properties, application. Nomenclature, isomeria amines

Aromatic amines are called derivatives of aromatic hydrocarbons, in which one or more hydrogen atoms of the benzene ring are replaced by amino groups (NH 2 ).

Aromatic amines can also be considered as derivatives of ammonia, in a molecule of which one or more hydrogen atoms are substituted with aromatic radicals.

As in an aliphatic (oily) row, aromatic amines can be primary, secondary and tertiary.

Depending on which radicals (only aromatic or aromatic and aliphatic) are associated with the nitrogen atom, they distinguish purely aromatic and fataromatic.

The amino group can be directly related to the kernel or located in the side chain.

Aniline is a phonod of class of aromatic amines, in which the amino group is directly related to the benzene ring:

anilin (phenylamine, aminobenzene)

Nomenclature of aromatic amines

For the name of aromatic amines, usually use trivial nomenclature.

For example, aniline, tolidine.

On systematic (replacement) nomenclature The names of the amines are formed from the names of radicals with the addition of completion -amine or consoles amino

Trivial: Orto-Toluidin Meta-Toluidin Pa-Toluidin

Replacement: Orto Tolilamine Meta Tolilamine Pa-Tolilamine

orto-aminotoluolet Meta-aminotoluoleol para-aminotowol

(2-aminotowol) (3-aminotoluolet) (4-aminotoluolet)

In the aromatic ring there may be two or more amino groups.

The names of compounds with two amino groups (diamines) are formed from the name of the bivalent carbon residue and end -Diamine or consoles diamino- and the name of the appropriate hydrocarbon:

o-Phoeniladiamine M-Phoeniladiamine P-Phlenilandiamine

o-diaminobenzene M-diaminobenzod P-diaminobenzene

(1,2-diaminobenzene) (1,3-diaminobenzene) (1,4-diaminobenzene)

Depending on the number of radicals associated with the nitrogen atom, secondary and tertiary aromatic amines are also distinguished.

The names of secondary and tertiary amines most often form according to principles rational nomenclature, Listing the radicals available in the connection and adding the end -amine:

diphenylamine (secondary amine)

triphenylamine (tertiary amine)

If in the amine molecule with a nitrogen atom, aromatic and aliphatic radicals are connected simultaneously, then such amines are called fataromatic.

In the case of fataromatic amines, the word is taken as the basis of the name "aniline" And to show that the radical is located at the nitrogen atom, and not in the benzene ring, the letter is put before the name of the radical N.:

N-methylaniline N, N-dimethylaniline

Rational: methylphenylamine dimethylphenylamine

Replacement: N-methylaminobenzene N, N-dimethylaminobenzene

Amines with an amino group in the side chain:

bezilamin

α-aminotoluolet

Aromatic amines with an amino group in the side chain possess the properties of aliphatic amines.

Aminami Ammonia derivatives are called, in which one, two go three hydrogen atoms are replaced by hydrocarbon radicals.

Depending on the number of hydrocarbon radicals distinguish primary , secondary and tertiary amines. There are also quaternary ammonium salts and basis , representing ammonium ion derivatives, in which all four hydrogen atoms are substituted with organic radicals. By nature, the Amina radical is divided into aliphatic and aromatic.

For amines more common names built by radical-functional , not at replacement nomenclature.

Generic title amines It refers to the compounds of RNH 2, RR "NH and RR" R "N, which are primary, secondary and tertiary amines, respectively. In a broader sense, the units include compounds containing a group -NH-in cycle.

Names primary amines Formed by adding suffix -amine to the name of the radical R (method but) or to the title of the general structure (method b). So, the compound CH 3 CH 2 CH 2 NH 2 will be called propylamine (but) or precanamine-1 (b). Method but Usually used for derivatives of simple compounds, and the method b. - For complex cyclic compounds. In the method but The principle of replacing the hydrogen atom in the ammonia molecule, which is formally a general structure is applied. In essence, it is similar to the principle of radical-functional nomenclature, but in the rules of Jew, refers to the substitution.

In cases where group -NH 2 is not a senior, it is indicated by the prefix amino -:

Some amines preserve trivial Names:

Primary diamines and polyamines, in which all amino groups are attached to an aliphatic chain or cyclic kernel, called sufifixes - dIAMIN. , -Triamine Both. To the title of the source structure or a multifaceted radical. The trivial name "benzidine" is preserved.

Symmetric secondary and tertiary amines call the attachment of multiplying consoles di- or three- To the names of alkyl radicals with suffix -amine. Asymmetrical compounds receive names like J-substituted primary amine derivatives, and for the initial primary amine, a compound with a more complex radical is taken:

The radicals of the amines RNH-, R 2 N-, RR "N- are called substituted amino groups or to the trivial names of amines add letter about:

Lower aliphatic amines - gases or liquids with a smell similar to the smell of ammonia. Higher homologues of aliphatic amines and aromatic amines are liquids or solids. Amines form weak hydrogen bonds and fragile associates, therefore their boiling points are lower than that of alcohols and carboxylic acids with the same number of carbon atoms, but higher than the aldehydes or ethers. The lower aliphatic amines are well soluble in water, with an increase in the number of hydrocarbon radicals and their length solubility decreases. Aromatic amines are poorly soluble in water.

Representatives.

Aniline - C 6 H 5 NH 2 - a colorless liquid with a weak odor, similar to the smell of benzene, when standing in the air is quite quickly oxidized and acquires yellow-brown color and unpleasant odor. Toxic.

More than half of the aniline produced is spent on the production of stabilizers and accelerators of volcanization of rubber. The second most important area of \u200b\u200bits application is the production of isocyanates used to obtain polyurethanes. Apply also in the production of dyes of various classes, medicines, photographic materials and plant protection products. In our country, aniline is used to obtain caprolactam.

N-methylaniline (Monomethulaniline) - C 6 H 5 NHCH 3 - is an oily liquid of yellow with a density of 0.98 g / cm 3, soluble in gasoline, alcohols and ether. The main task of monomethylanilina is to obtain the necessary detonation properties of gasoline during its production. In addition, when adding it to the fuel is regulated by the octane number of the product and its environmental friendliness.

Dimethylaniline - C 6 H 5 N (CH 3) 2 - Tertiary fataromatic amine, colorless liquid. It is used in the production of polyester resins and in organic synthesis. Dimethylaniline is used in the synthesis of dyes (malachite green, methylene blue, etc.), explosives, etc.

Toluidins - CH 3 C 6 H 4 NH 2 - colorless crystal compounds with peculiar smells, in the air are quickly oxidized and darkened. Get the restoration of nitrotoluols. Apply in the production of dyes of different classes (triphenylmethetan, azocrase, thiazine, sulfur), as well as to obtain crosses. Toluidins, like some other aromatic amines, poisonous and carcinogenic.

Phenetidina (ethoxyanilines, aminophoretoles) - NH 2 -C 6 H 4 -OC 2 H 3 (ortho, para- and meta-) - represent liquids. Used in the production of nitrogen; N-phenetidine is also in the synthesis of drug resources (fenacetin, rivangol). Phenetidines cause poisoning when entering the skin and inhalation of vapors, the liver and kidneys are affected.

Diphenylamine ((N-phenyl) -anilin) \u200b\u200b- (C 6 H 5) 2 NN - colorless crystals, dark-skinned. Diphenylamine is the source product in the production of antioxidants for polymers; stabilizer and phlegmatizer of thermo- and weather resistance of cellulose nitrates, including pyroxiline powder; intermediate product in the synthesis of triarrylmetan and azocrase, insecticides; Corrosion inhibitor of soft steels. Used in analytical chemistry to detect ions, as a redox indicator.

Spectral characteristics.

IR spectroscopy. . The position of the absorption bands of the amino group in the spectrum is determined by the conditions of shooting of the spectra (in solid form, liquid state, in solutions or the gas phase) and depends on whether the amino group is free (non-associated) or it is involved in the formation of inter- and intramolecular hydrogen bonds.

The absorption bands caused by valence fluctuations of the N-H bonds are manifested in the IR spectra in the area of \u200b\u200b3500-3200 cm -1. Primary amines have two absorption bands. High-frequency is due to asymmetric valence oscillations N-H, less high-frequency - symmetric. In the spectra of amines in dilute solutions in the inert solvents, these two narrow bands are observed at 3500 and 3400 cm -1. Secondary amines have one absorption band corresponding to N-N valent fluctuations. For aliphatic amines in inert solvents, it is observed in the region of 3350-3310 cm -1, in the spectra of mixed amines AG-NH-Alk, the absorption band N-H is located at higher frequencies of 3450 cm -1.

If the amino group is involved in inter- or intramolecular hydrogen bond (in a solid or liquid state, in concentrated solutions), then the absorption bands of the valence oscillations N-H are shifted in a low-frequency side. However, this offset is not so significant. Associated primary amines give absorption bands in areas 3420-3330 cm -1 (V asnh 2) and 3330-3250 cm -1 (V SNH 2), secondary - in the region of 3300-3150 cm -1. In case of incomplete association, both the bands of a free and associated amino group can be observed, therefore, in the region of 3500-3200 cm -1, there may be more than two bands characteristic of primary amines, and more than one strip characteristic of secondary.

The deformation oscillations of the amino group are observed in the region of 1650-1500 and 950-650 cm -1. Primary amines have the absorption bands of flat deformation oscillations of the average intensity of 1650-1580 cm -1, secondary - weak intensity in the range of 1600-1500 cm -1. In the formation of hydrogen bonds, the frequency of deformation oscillations increases.

Amines also have bands of absorption of valence oscillations C-N. In aliphatic amines, this oscillation corresponds to the absorption in the region 1250-1020 cm -1 average intensity, in aromatic amines - intensive absorption in the frequency range 1340-1260 cm -1.

The interaction of amines with acids causes severe changes in the spectra. In the salts of primary amines, the oscillations n-H corresponds to a wide strong band in the 3100-2600 cm -1 region. Salts of secondary and tertiary amines have intensive absorption in the region of 2700-2250 cm -1. Aminic salts can be additionally identified by deformation fluctuations. The salts of primary amines are absorbed in the region 1600-1575 and 1550-1500 cm -1, the salts of secondary amines - in the range of 1620-1560 cm -1.

Spectroscopy of PMR . Signals of protons of the group NH aliphatic and cyclic amines are observed in the range of 0.5-3.0 m., Aromatic amines - at 3.0-5.0 m. D. Since the amines can form hydrogen bonds, the position of the signals depends on the concentration Amina, nature of the solvent and temperature. The protons of the NH group can exchange on deuterium, and when it is added to a heavy water sample D 2 O, these signals disappear.

Amino group, which is in pairing with a benzene ring increases electron density in ortho- and couple - Rings of the ring, which leads to the shielding of the corresponding protons and mixing their signals into a stronger field compared to benzene. In the spectra of the PMR as amines, the signals of aromatic protons are complex multiplets.

Electronic spectroscopy . Aliphatic amines in the UV and visible region do not absorb . The conjugation of amino groups with a benzene ring leads to a significant battalo offset of benzene absorption bands with an increase in their intensity. It is believed that along with the local π → π * -proof of the benzene ring in this absorption contributes the transition to the transfer of charge from the donor group to the ring (aniline. Aniline in the near UV region has two absorption bands - 230 nm and 280 nm.

Amines: Acid-basic properties; Nucleophilic properties - alkylation reactions of amines and ammonia, quaternary ammonium salts, disclosure  -Oxygen cycle amines to form aminopirts.

Chemical properties.

In the molecules of aliphatic amines, the nitrogen atom is in a state sp. 3 -Hypebridization, so they, like ammonia, have a pyramidal configuration. For example, the corners of the C-N-C bonds in trimethylamine are equal to 108 ° and very close to the values \u200b\u200bof the H-N-N angles in the ammonia molecule.

Theoretically, secondary and tertiary amines with different hydrocarbon radicals may exist in the form of enantiomers, but the usual aliphatic and aromatic amines are still not allocated in the form of individual enantiomers. This is explained by the fact that ammonia and amine molecules constantly undergo a pyramidal inversion, which should be considered as fast configuration. Inversion is carried out through a trigonal transition state (in the center of the scheme):

In the molecules of aromatic amines, the esilient pair of electrons of the nitrogen atom is in conjugation with π -Electrons of the aromatic ring, as a result of which the amplitude with which the pyramid inversion is performed is significantly reduced.

Quaternary ammonium salts having four different radicals can be divided into individual enantiomeric forms, i.e., these forms have configuration stability. Thus, allylis isolated in the form of individual enantiomers, each of which has optical activity:

Basic properties.

Amines, like ammonia, show the main properties, due to the presence of nitrogen atoms in their molecules with a mean pair of electrons. When interacting with the acids of amines turn into ammonium salts :

Aminic salts, in contrast to other onion salts, hydrolytically stable, are well soluble in water, easily crystallized from aqueous solutions and, as a rule, more stable than free bases. Many medicinal substances relating to the class of amines are used in the form of salts with mineral and less often organic acids.

Aliphatic amines - strong bases . Aquatic amine solutions have an alkaline environment in Lacmus:

It can be assumed that tertiary amines with three alkyl substituents with + i-effect will be stronger bases than secondary and primary amines. However, steric factors that determine the availability of the main center for the proton attack have the opposite effect. The greater the nitrogen atom of the radicals and what they branched, the stronger the vapor pair of electrons of the nitrogen atom is shielded and its interaction with the proton is difficult. Therefore, the most powerful bases should be primary and secondary amines with relatively short and unbranched radicals. The solvation (the interaction of the solute molecule with the solvent molecules) has an influence similar to the influence of steric factors for basicity, since with an increase in the number and branching of hydrocarbon radicals, the ability of a substituted ammonium cation (conjugate acid) is reduced to bind the solvent molecules.

Many experimental data do not fit into the above relatively simple schemes. Thus, purely speculative reasoning cannot serve as a reliable basis for predicting the comparative basicity of aliphatic amines. In practice, it can be guided by the fact that the values \u200b\u200bof the RK VN + most aliphatic amines are stacked in a relatively narrow interval: from 10.6 to 11.2. Such a slight difference in basicity does not provide a significant advantage of some of the amines in the competitive protonation reaction.

The basicity of aromatic amines is significantly lower than that of the amines of an aliphatic series. This is explained by the fact that the essential pair of electrons of the nitrogen atom enters into p, π-conjugation with the electron of the benzene ring:

The substituents in the ring significantly affect the basicity: it is increased by electronic substituents, and electronically accurate reduced.

If, due to steric difficulties, the marginal pair of electrons is derived from the conjugation, the baseness of the amine increases significantly. Thus, the volumetric alkyl radicals N, N-diisopropylaniline cannot be located in one plane with a benzene ring due to mutual repulsion with hydrogen atoms in ortho-positions, therefore its basicity (PK BH + 7.4) is significantly higher than that of aniline. A similar kind of steric difficulties occur in N, N-dialkylanilines, having both substituents in positions in positions 2 and 6. In the molecule of 1.8-bis (dimethylamino) naphthalene both dimethylamino groups also cannot be located in the same plane with an aromatic system, and this connection has surprisingly High basicity (RKVN + 12.4), its protonated form is stable due to the fact that the proton is firmly held by the empty pairs of the electronic nitrogen atoms.

Acid Properties.

NH acid properties of amines are expressed significantly less than basic. For aliphatic and aromatic primary and secondary amines of the Republic of Kazakhstan A. have values \u200b\u200bof 30-35. Thus, more weak acids than amines are except alkanes. Amines eye acidic properties only in the presence of very strong grounds , such as, for example, metal organic compounds, and turn into amida Metals (not to be confused with carbon and sulfonic acid amides!):

Alkali metal amides are very strong bases and are used in organic synthesis.

Nucleophilic properties.

The nucleophilic properties of amines, as well as the main, are due to the presence of a mean-free pair of electrons of the nitrogen atom. Some reactions in which the amines participate as nucleophilic reagents will be further and were previously. This is alkylation of amines [(1)], interaction with carbonyl compounds [(2)] and acylation of carboxylic acid derivatives [(3)]:

Alkylation. Amines, like ammonia, are subjected to alkylation of halogenalkas. The alkylation of ammonia leads to the formation of a primary amine, secondary, from the secondary - tertiary, from tertiary - quaternary ammonium salts are formed from the primary amines. The substituted ammonium salt during the reaction is exchanged by a proton with ammonia or amine, so in the alkylation reaction, a mixture of amines with different numbers of alkyl radicals is obtained:

The alkylation reaction is rarely able to stop at some separate stage due to the fact that the differences in the nucleophilicity and the basicity of primary, secondary and tertiary amines are not so significant in order to affect the difference in the speeds of alkylation reactions of amines of different degrees.

In the ammonia industry and lower amines alkylated with lower alcohols in the gas phase at a temperature of 300-500 ° C above aluminum oxides, silicon, thorium, chromium and others. At the same time, mixtures of primary, secondary and tertiary amines are formed. This method is obtained mainly methyl and ethylasines:

Reactions amines with epoxides. In the interaction of primary and secondary amines with epoxides (oxiranes), a nucleophilic disclosure of a strained three-membered α-oxide cycle occurs and β-aminopirts are formed. In substituted epoxides, the nucleophilic attack occurs, as a rule, to the least substituted atom of carbon of the oxide cycle ( rule of Krasovsky ):

Topic Lectures: Aminines and Aminepirts

Questions:

General characteristics: Building, classification, nomenclature.

Methods of receipt

Physical properties

Chemical properties

Separate representatives. Identification methods.

General characteristics: Building, classification, nomenclature

Aminams are called ammonia derivatives, whose molecule of hydrogen atoms are substituted for hydrocarbon radicals.

Classification

1- Depending on the number of substituted hydrogen atoms, ammonia distinguish the amines:

– primarycontain amino group amino group (-NH 2), general formula: R-NH 2,

– secondary contain an imino group (-NH),

general formula: R 1 -NH-R 2

– tertiary contain a nitrogen atom, general formula: R 3 -N

Also known compounds with a quaternary nitrogen atom: Quaternary ammonium hydroxide and its salt.

2- Depending on the structure of the Amina radical distinguish:

- Aliphatic (limit and unforeseen)

- Alicyclic

- Aromatic (containing amino group or side chains in the kernel)

- heterocyclic.

Nomenclature, isomeria amines

1. The names of amines in rational nomenclature are usually produced from the names of hydrocarbon radicals included in them with the connection of the end -amine : methyline CH 3 -NN 2, dimethylamine CH 3 -NN-CH 3, trimethylamine (CH 3) 3 n, prophylamine CH 3 CH 2 CH 2 -NH 2, phenylamine C 6 H 5 - NN 2, etc.

2. According to the Nomenclature of the Republic of China, the amino group is considered as a functional group and its name aminoput before the title of the main chain:

Isomerius amines depends on isomerism of radicals.

Methods for producing amines

Amines can be obtained in various ways.

A) action on ammonia haloalkyls

2NH 3 + CH 3 I --® CH 3 - NH 2 + NH 4 I

B) catalytic hydrogenation of nitrobenzene by molecular hydrogen:

From 6 N 5 NO 2 --® C 6N 5 NN 2 + H 2 O

nitrobenzene Cat Anilin

C) obtaining lower amines (C 1 -C 4) by alkylation by alcohols:

350 0 C, Al 2 O 3

R-OH + NH 3 ----------- ® R-NH 2 + H 2 O

350 0 C, Al 2 O 3

2R-OH + NH 3 ----------- ® R 2 -NH + 2H 2 O

350 0 C, Al 2 O 3

3R-OH + NH 3 ----------- ® R 3 -N + 3H 2 O

Physical properties of amines

Methyline, dimethylamine and trimethylamine - gases, medium members of a number of amines - liquids, higher - solid bodies. With an increase in the molecular weight of amines, their density increases, the boiling point increases and the solubility in water is reduced. Higher amines in water are insoluble. Lower amines have an unpleasant smell, somewhat resembling the smell of spoiled fish. Higher amines or do not smell, or have a very weak odor. Aromatic amines are colorless liquids or solids with unpleasant odor and poisonous.

Chemical properties of amines

Chemical behavior of amines is determined by the presence of an amino group in the molecule. There are 5 electrons on the outer electron shell of the nitrogen atom. In an amine molecule, as in the ammonia molecule, the nitrogen atom spends three electrons on the formation of three covalent bonds, and two remain free.

The presence of a free electronic pair at the nitrogen atom gives him the opportunity to attach a proton, so ammonia is similar to ammonia, the main properties appear, form hydroxides, salts.

Salt formation. Amines with acids give salts that, under the action of a strong base, freely give free amines:

Amines give salts even with weak coal acid:

Like ammonia, the amines have the basic properties that is explained by the binding of protons in a weak dissociating cation of substituted ammonium:

When the amine is dissolved in water, part of the water protons is spent on the formation of the cation; Thus, an excess of hydroxide ions appears in the solution, and it has alkaline properties sufficient to dye the solutions of the Lacmus in blue and phenolphthalene in the raspberry. The basicity of the amines of the limit range fluctuates in very small limits and is close to the basicity of ammonia.

The effect of methyl groups somewhat increases the basicity of methyl and dimethylamine. In the case of trimethylamine, methyl groups make it difficult to solvate the resulting cation and reduce its stabilization, and, consequently, basicity.

Aminic salts should be considered as complex compounds. The central atom in them is a nitrogen atom, whose coordination number is four. Hydrogen or alkyl atoms are connected to the nitrogen atom and are located in the inner sphere; Acid residue is located in the outer sphere.

Aminic acylation. Under action on primary and secondary amines of some derivatives of organic acids (halogenanthydrides, anhydrides, etc.), amides are formed:

Secondary amines with nitrogen acid give nitrosoamine- yellowish liquids, poorly soluble in water:

Tertiary amines are resistant to the action of diluted nitrogenous acid on cold (form salts of nitrate acid), in more stringent conditions, one of the radicals is cleaved and nitrosoamine is formed.

Diamines

Diamine plays an important role in biological processes. As a rule, they are easily soluble in water, have a characteristic odor, have a strongly alkaline reaction, interact with C0 2 air. Diamines form resistant salts with two equivalents of acid.

Ethylenediamine (1,2-ethanine) H 2 NCH 2 CH 2 NN 2. He is the simplest diamin; May be obtained by ammonia on ethylenebromide:

Tetramethylenediamine. (1,4-butdamine), or Pretrad, NN 2 CH 2 CH 2 CH 2 CH 2 NH 2 and pentamethylenediamine. (1,5-pentandamine) NN 2 CH 2 CH 2 CH 2 CH 2 CH 2 NN 2, or Cadaverin. They were discovered in products decomposition of protein substances; are formed during decarboxylation of diamino acids and named ptomaians(from Grech. - Corpse), they were considered previously "body poisons". Currently it is found that the poisonousness of rotting proteins is not caused by non-Ptomaians, but the presence of other substances.

Pretrassin and Cadaverin are formed as a result of the vital activity of many microorganisms (for example, tetanus and cholera causative agents) and fungi; They are found in cheese, ardor, mumor, beer yeast.

Some diamines are used as raw materials to produce polyamide fibers and plastics. So, from hexa-methylenediamine NN 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 NN 2 Received Very valuable synthetic fiber - nylon(USA) or anid(Russia).

Aminospirts

Aminospirts- Compounds with mixed functions, in which the molecule contains amino and oxygroups.

Aminoethanol(ethanolamine) but-CH 2 CH 2 -NH 2, or Koloming.

Ethanolamine is a thick oil liquid, mixed with water in all respects, has strong alkaline properties. Diethanolamine and triethanolamine are also obtained with monoethanolamine:

Holine is part of lecitinov- zip-like substances, very common in animals and vegetable organisms, and can be isolated from them. Holine is a crystalline, very hygroscopic, easily spacing a mass. It has strong alkaline properties and with acids easily forms salts.

When coiling choline, acetic anhydride is formed holinacetate,called as well acetylcholine:

Acetylcholine plays an extremely important biochemical role, as it is a mediator (intermediary) transmitting excitement from nervous receptors to the muscles.

Amines are organic compounds that are considered as an ammonia derivatives in which hydrogen atoms (one, two or three) are seen on hydrocarbon radicals. Amines are divided into primary, secondary, tertiary depending on how many hydrogen atoms are substituted on the radical: /\u003e

primary	Secondary	Tertiary
amines	amines	amines

There are also organic analogues of ammonium salts - this quaternary salts type [R 4 N] + Cl -.

Depending on the nature of the radicals, the amines can be aliphatic (limit and unforeseen), alicyclic, aromatic or mixed.

Limit aliphatic amines

General formula of limit aliphatic amines with N 2 n +3 n.

Building. / \u003e. Nitrogen atom in amine molecules is in a statesp. 3 -Hybridization. Three of the four hybrid orbitals are involved in the formation of σ-linksN - C and N - H The fourth orbital is a vapor electronic couple, which causes the basic properties of amines.The names of the amines are usually produced by lizing the hydrocarbon radicals (in alphabetical order) and adding the ending -amin, for example:

Electroneal substituents (limiting hydrocarbon radicals) increase electron density on the nitrogen atom and strengthen the basic properties of amines, so secondary amines - stronger bases than primary, since two radicals create a large electron density on a nitrogen atom than one. In tertiary amines, a spatial factor plays an important role: three radicals are blocked by an electronic pair of nitrogen atom and make it difficult to interact with other molecules, therefore the basicity of tertiary amines is less than primary or secondary.

The basicity constants of ammonia and lower amines: X + N 2 HH + + he -

Isomeria aminov is associated with the structure of the carbon skeleton and the position of the amino group:

In addition, primary, secondary and tertiary amines containing the same number of carbon atoms are isomeric among themselves, for example:

CH 3 -CH 2 -NH 2 CH 3 -NH-CH 3

ethylamine dimethylamine

Nomenclature.

C 2 H 5 - NH 2 CH 3 - NH - C 2 H 5 (CH 3) 3 N
Ethylamine methyl ethylamine trimethylamine

On another system, the name of the primary amines is built, based on the name of the source hydrocarbon and adding the ending -amin indicating the number of the carbon atom associated with the amino group.

Physical properties. />Methyline, dimethylamine and trimethylamine - gases, average members of an aliphatic series - liquid, higher - solids. Weak hydrogen bonds are formed between the amine molecules in the liquid phase, therefore the boiling point of amines is higher than that of the corresponding hydrocarbons.

The amines also form weak hydrogen bonds with water, so lower amines are well soluble in water, as the carbon skeleton grows, the solubility in water is reduced. Lower amines have a characteristic "fish" smell, the highest no smell.

Since the amines, being derived from ammonia, have a building similar to it (i.e., have a watelling pair of electrons in the nitrogen atom), then they exhibit the properties similar to it. Those. Amines, as well as ammonia, are grounds, since a nitrogen atom can provide an electron pair to form a bond with electronized particles according to a donor-acceptor mechanism (compliance with the definition of support for Lewis).

I. Properties of amines as grounds (protons acceptors)

1. Aqueous solutions of aliphatic amines exhibit an alkaline reaction, because When they interact with water, alkyllammonium hydroxides are formed similar to ammonium hydroxide:

CH 3 NH 2 + H 2 O CH 3 NH 3 + + OH -

Aniline with water practically does not react.

Aqueous solutions have an alkaline character:

The communication of the proton with the amine, as with ammonia, is formed according to the donor-acceptor mechanism due to the vulnerable electronic pair of the nitrogen atom.

Aliphatic amines - stronger bases than ammonia, because Alkyl radicals increase electron density on the nitrogen atom due to + I.- Effect. For this reason, an electron pair of a nitrogen atom is held less firmly and easier interacts with the proton.

2. Interacting with acids, the amines form salts:

C 6 H 5 NH 2 + HCl → (C 6 H 5 NH 3) Cl

chloride phenylammonium

2ch 3 NH 2 + H 2 SO 4 → (CH 3 NH 3) 2 SO 4

methylmmonium sulfate

Aminic salts are solids that are well soluble in water and are poorly soluble in non-polar fluids. When reactions with alkalis, free amines are highlighted:

Aromatic amines are more weak grounds than ammonia, since a vapor electronic pair of a nitrogen atom is shifted towards the benzene ring, entering into a conjugation with π electrons of the aromatic nucleus, which reduces the electron density on the nitrogen atom (-m-effect). On the contrary, the alkyl group is a good electron donor donor (+ i-effect) ..

or

Reducing the electron density on the nitrogen atom leads to a decrease in the ability to split protons from weak acids. Therefore, aniline interacts only with strong acids (HCl, H 2 SO 4), and its aqueous solution does not paint the lactium into blue color.

The nitrogen atom in the amines molecules there is a marginal pair of electrons, which can participate in the formation of communication on the donor-acceptor mechanism.

aniline Ammonia Primary Amin Secondary Amin Tertiary Amin

electronic density on the nitrogen atom increases.

Due to the presence of a vapor pair of electron electron, as ammonia, the main properties are manifested in molecules.

aniline Ammonia Primary Amin Secondary Amin

the main properties are enhanced due to the influence of the type and number of radicals.

C 6 H 5 NH 2< NH 3 < RNH 2 < R 2 NH < R 3 N (в газовой фазе)

II. Aminic oxidation

Amines, especially aromatic, easily oxidized in air. Unlike ammonia, they are able to ignite the open flame. Aromatic amines are spontaneously oxidized in air. So, aniline will quickly boil in air due to oxidation.

4SH 3 NH 2 + 9O 2 → 4CO 2 + 10H 2 O + 2N 2

4C 6 H 5 NH 2 + 31O 2 → 24CO 2 + 14H 2 O + 2N 2

III. Interaction with nitrate acid

Nitrogenous acid HNO 2 is an unstable connection. Therefore, it is used only at the time of allocation. HNO 2 is formed, as all weak acids, the action on its salt (nitrite) with strong acid:

KNO 2 + HCL → NNO 2 + KCL

or NO 2 - + H + → NNO 2

The structure of the reaction products with nitrogen acid depends on the nature of the amine. Therefore, this reaction is used to distinguish between primary, secondary and tertiary amines.

· Primary aliphatic amines with HNO 2 form alcohols:

R-NH 2 + HNO 2 → R-OH + N 2 + H 2 O

• The reaction of diazotizing primary aromatic amines under the action of nitrogenic acid obtained by the sodium nitrite reaction with hydrochloric acid is of great importance. And later the phenol is formed:

· Secondary amines (aliphatic and aromatic) under the action of HNO 2 are converted to N-nitro-produced (substances with a characteristic odor):

R 2 NH + H-O - N \u003d O → R 2 n-n \u003d O + H 2 O

alkylnitrousamine

· The response with tertiary amines leads to the formation of unstable salts and does not have a practical value.

IV. Special properties:

1. The formation of complex compounds with transition metals:

2. The addition of alkyl halides Amina attach halogens with salt formation:

Processing the resulting salt alkali, you can get a free amine:

V. Aromatic electrophile substitution in aromatic amines (aniline reaction with bromine water or with nitric acid):

In aromatic amines, the amino group facilitates replacement in ortho and para-positions of the benzene ring. Therefore, the halogenation of aniline occurs quickly and in the absence of catalysts, and the three atoms of hydrogen of the benzene ring are replaced, and a white precipitate of 2,4,6-tribromanyline falls out:

This reaction of bromine water is used as a high-quality reaction to aniline.

In these reactions (bromination and nitration) are mostly formed ortho- I. couple-Cheel.

4. Methods for producing amines.

1. Reaction of Hoffman. One of the first methods for obtaining primary amines - alkylation of ammonia alkyl halides:

This is not the best method, as the result is a mixture of amines of all detection of substitution:

etc. Alkylating agents can be not only alkyl halides, but also alcohols. For this, the ammonia and alcohol mixture is passed over aluminum oxide at high temperature.

2. Reaction Zinin - A convenient way to obtain aromatic amines when restoring aromatic nitro compounds. As reducing agents are used: H 2 (on the catalyst). Sometimes hydrogen is generated directly at the moment of the reaction, for which metals (zinc, iron) diluted with acid are treated.

2HCl + FE (chips) → FECL 2 + 2H

C 6 H 5 NO 2 + 6 [H] C 6 H 5 NH 2 + 2H 2 O.

In industry, this reaction occurs when nitrobenzene is heated with water vapor in the presence of iron. In the laboratory, hydrogen "at the time of release" is formed by zinc reaction with alkali or iron with hydrochloric acid. In the latter case, analine chloride is formed.

3. Restoration of nitriles. Use LiAlh 4:

4. Fermental decarboxylation of amino acids:

5. Application of amines.

Amines are used in the pharmaceutical industry and organic synthesis (CH 3 NH 2, (CH 3) 2 NH, (C 2 H 5) 2 NH, etc.); in the production of nylon (NH 2 - (CH 2) 6 -NH 2 - hexamethylenediamine); As raw materials for the production of dyes and plastics (aniline), as well as pesticides.

List of sources used:

1. O.S. Gabrielyan and others. Chemistry. Grade 10. Profile level: textbook for general education institutions; Drop, Moscow, 2005;
2. "Chemistry tutor" edited by A. S. Egorova; "Phoenix", Rostov-on-Don, 2006;
3. E. Rudzitis, F. G. Feldman. Chemistry 10 cl. M., Enlightenment, 2001;
4. https://www.calc.ru/aminy-svoystva-aminov.html
5. http://www.yaklass.ru/materiali?mode\u003dlsntheme&themeid\u003d144.
6. http://www.chemel.ru/2008-05-24-19-21-00/2008-06-01-16-50-05/193-2008-06-30-20-47-29.html
7. http://cnit.ssau.ru/organics/chem5/n232.htm.