All amine formulas. Amines - concept, properties, application. Individual representatives. Identification methods

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:

1. ethylenediamine
2. aniline
3. 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

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 - these are derivatives of ammonia (NH 3), in the molecule of which one, two or three hydrogen atoms are replaced by hydrocarbon radicals.

According to the number of hydrocarbon radicals replacing hydrogen atoms in the NH 3 molecule, all amines can be divided into three types:

The group - NH 2 is called an amino group. There are also amines that contain two, three or more amino groups

Nomenclature

The word “amine” is added to the name of organic residues associated with nitrogen, and the groups are mentioned in alphabetical order: CH3NC3H - methylpropylamine, CH3N(C6H5)2 - methyldiphenylamine. For higher amines, the name is compiled using the hydrocarbon as a basis, adding the prefix “amino”, “diamino”, “triamino”, indicating the numerical index of the carbon atom. For some amines, trivial names are used: C6H5NH2 - aniline (systematic name - phenylamine).

For amines, chain isomerism, functional group position isomerism, and isomerism between types of amines are possible

Physical properties

Low-limit primary amines are gaseous substances, have an ammonia odor, and are highly soluble in water. Amines with a higher relative molecular weight are liquids or solids; their solubility in water decreases with increasing molecular weight.

Chemical properties

Amines have similar chemical properties to ammonia.

1. Interaction with water - the formation of substituted ammonium hydroxides. A solution of ammonia in water has weak alkaline (basic) properties. The reason for the basic properties of ammonia is the presence of a lone electron pair on the nitrogen atom, which participates in the formation of a donor-acceptor bond with a hydrogen ion. For the same reason, amines are also weak bases. Amines are organic bases.

2. Interaction with acids - formation of salts (neutralization reactions). As a base, ammonia forms ammonium salts with acids. Similarly, when amines react with acids, substituted ammonium salts are formed. Alkalies, as stronger bases, displace ammonia and amines from their salts.

3. Combustion of amines. Amines are flammable substances. The combustion products of amines, like other nitrogen-containing organic compounds, are carbon dioxide, water and free nitrogen.

Alkylation is the introduction of an alkyl substituent into a molecule of an organic compound. Typical alkylating agents are alkyl halides, alkenes, epoxy compounds, alcohols, and less commonly aldehydes, ketones, ethers, sulfides, and diazoalkanes. Alkylation catalysts include mineral acids, Lewis acids and zeolites.

Acylation. When heated with carboxylic acids, their anhydrides, acid chlorides or esters, primary and secondary amines are acylated to form N-substituted amides, compounds with the -C(O)N moiety<:

The reaction with anhydrides occurs under mild conditions. Acid chlorides react even more easily; the reaction is carried out in the presence of a base to bind the resulting HCl.

Primary and secondary amines react with nitrous acid in different ways. Nitrous acid is used to distinguish primary, secondary and tertiary amines from each other. Primary alcohols are formed from primary amines:

C2H5NH2 + HNO2 → C2H5OH + N2 +H2O

This releases gas (nitrogen). This is a sign that there is a primary amine in the flask.

Secondary amines form yellow, poorly soluble nitrosamines with nitrous acid - compounds containing the fragment >N-N=O:

(C2H5)2NH + HNO2 → (C2H5)2N-N=O + H2O

Secondary amines are difficult to miss; the characteristic smell of nitrosodimethylamine spreads throughout the laboratory.

Tertiary amines simply dissolve in nitrous acid at ordinary temperatures. When heated, a reaction with the elimination of alkyl radicals is possible.

Methods of obtaining

1. Interaction of alcohols with ammonia when heated in the presence of Al 2 0 3 as a catalyst.

2. Interaction of alkyl halides (haloalkanes) with ammonia. The resulting primary amine can react with excess alkyl halide and ammonia to form a secondary amine. Tertiary amines can be prepared similarly

Amino acids. Classification, isomerism, nomenclature, production. Physical and chemical properties. Amphoteric properties, bipolar structure, isoelectric point. Polypeptides. Individual representatives: glycine, alanine, cysteine, cystine, a-aminocaproic acid, lysine, glutamic acid.

Amino acids- these are derivatives of hydrocarbons containing amino groups (-NH 2) and carboxyl groups -COOH.

General formula: (NH 2) f R(COOH) n where m and n most often equal to 1 or 2. Thus, amino acids are compounds with mixed functions.

Classification

Isomerism

The isomerism of amino acids, like hydroxy acids, depends on the isomerism of the carbon chain and on the position of the amino group relative to the carboxyl (a-, β - and γ - amino acids, etc.). In addition, all natural amino acids, except aminoacetic acid, contain asymmetric carbon atoms, so they have optical isomers (antipodes). There are D- and L-series of amino acids. It should be noted that all amino acids that make up proteins belong to the L-series.

Nomenclature

Amino acids usually have trivial names (for example, aminoacetic acid is called differently glycol or icin, and aminopropionic acid - alanine etc.). The name of an amino acid according to systematic nomenclature consists of the name of the corresponding carboxylic acid of which it is a derivative, with the addition of the word amino- as a prefix. The position of the amino group in the chain is indicated by numbers.

Methods of obtaining

1. Interaction of α-halocarboxylic acids with excess ammonia. During these reactions, the halogen atom in halogenated carboxylic acids (for their preparation, see § 10.4) is replaced by an amino group. The resulting hydrogen chloride is bound by excess ammonia to form ammonium chloride.

2. Protein hydrolysis. The hydrolysis of proteins usually produces complex mixtures of amino acids, but using special methods, individual pure amino acids can be isolated from these mixtures.

Physical properties

Amino acids are colorless crystalline substances, readily soluble in water, melting point 230-300°C. Many α-amino acids have a sweet taste.

Chemical properties

1. Interaction with bases and acids:

a) as an acid (a carboxyl group is involved).

b) as a base (an amino group is involved).

2. Interaction inside the molecule - the formation of internal salts:

a) monoaminomonocarboxylic acids (neutral acids). Aqueous solutions of monoaminomonocarboxylic acids are neutral (pH = 7);

b) monoaminodicarboxylic acids (acidic amino acids). Aqueous solutions of monoaminodicarboxylic acids have a pH< 7 (кислая среда), так как в результате образования внутренних солей этих кислот в растворе появляется избыток ионов водорода Н + ;

c) diaminomonocarboxylic acids (basic amino acids). Aqueous solutions of diaminomonocarboxylic acids have a pH > 7 (alkaline environment), since as a result of the formation of internal salts of these acids, an excess of OH - hydroxide ions appears in the solution.

3. The interaction of amino acids with each other - the formation of peptides.

4. React with alcohols to form esters.

The isoelectric point of amino acids that do not contain additional NH2 or COOH groups is the arithmetic mean between two pK values: respectively for alanine .

The isoelectric point of a number of other amino acids containing additional acidic or basic groups (aspartic and glutamic acids, lysine, arginine, tyrosine, etc.) also depends on the acidity or basicity of the radicals of these amino acids. For lysine, for example, pI should be calculated from half the sum of pK values ​​for α- and ε-NH2 groups. Thus, in the pH range from 4.0 to 9.0, almost all amino acids exist predominantly in the form of zwitterions with a protonated amino group and a dissociated carboxyl group.

Polypeptides contain more than ten amino acid residues.

Glycine (aminoacetic acid, aminoethanoic acid) is the simplest aliphatic amino acid, the only amino acid that does not have optical isomers. Empirical formula C2H5NO2

Alanine (aminopropanoic acid) is an aliphatic amino acid. α-alanine is part of many proteins, β-alanine is part of a number of biologically active compounds. Chemical formula NH2 -CH -CH3 -COOH. Alanine is easily converted into glucose in the liver and vice versa. This process is called the glucose-alanine cycle and is one of the main pathways of gluconeogenesis in the liver.

Cysteine ​​(α-amino-β-thiopropionic acid; 2-amino-3-sulfanylpropanoic acid) is an aliphatic sulfur-containing amino acid. Optically active, exists in the form of L- and D-isomers. L-Cysteine ​​is part of proteins and peptides and plays an important role in the formation of skin tissue. Important for detoxification processes. Empirical formula C3H7NO2S.

Cystine (chemical) (3,3"-dithio-bis-2-aminopropionic acid, dicysteine) is an aliphatic sulfur-containing amino acid, colorless crystals, soluble in water.

Cystine is a non-coded amino acid that is a product of the oxidative dimerization of cysteine, during which two thiol groups of cysteine ​​form a cystine disulfide bond. Cystine contains two amino groups and two carboxyl groups and is a dibasic diamino acid. Empirical formula C6H12N2O4S2

In the body they are found mainly in proteins.

Aminocaproic acid (6-aminohexanoic acid or ε-aminocaproic acid) is a hemostatic drug that inhibits the conversion of profibrinolysin to fibrinolysin. Gross-

formula C6H13NO2.

Lysine (2,6-diaminohexanoic acid) is an aliphatic amino acid with pronounced base properties; essential amino acid. Chemical formula: C6H14N2O2

Lysine is part of proteins. Lysine is an essential amino acid, part of almost any protein, necessary for growth, tissue repair, production of antibodies, hormones, enzymes, albumins.

Glutamic acid (2-aminopentanedioic acid) is an aliphatic amino acid. In living organisms, glutamic acid in the form of the glutamate anion is present in proteins, a number of low-molecular substances and in free form. Glutamic acid plays an important role in nitrogen metabolism. Chemical formula C5H9N1O4

Glutamic acid is also a neurotransmitter amino acid, one of the important representatives of the class of “excitatory amino acids”. The binding of glutamate to specific neuronal receptors leads to the excitation of the latter.

Simple and complex proteins. Peptide bond. The concept of the primary, secondary, tertiary and quaternary structure of a protein molecule. Types of bonds that determine the spatial structure of the protein molecule (hydrogen, disulfide, ionic, hydrophobic interactions). Physical and chemical properties of proteins (precipitation reactions, denaturation, color reactions). Isoelectric point. The meaning of proteins.

Proteins - These are natural high-molecular compounds (biopolymers), the structural basis of which is made up of polypeptide chains built from α-amino acid residues.

Simple proteins (proteins) are high-molecular organic substances consisting of alpha-amino acids connected in a chain by a peptide bond.

Complex proteins (proteids) are two-component proteins that, in addition to peptide chains (simple protein), contain a non-amino acid component - a prosthetic group.

Peptide bond - a type of amide bond that occurs during the formation of proteins and peptides as a result of the interaction of the α-amino group (-NH2) of one amino acid with the α-carboxyl group (-COOH) of another amino acid.

Primary structure is the sequence of amino acids in a polypeptide chain. Important features of the primary structure are conserved motifs - combinations of amino acids that play a key role in protein functions. Conserved motifs are conserved throughout the evolution of species and can often be used to predict the function of an unknown protein.

Secondary structure is the local ordering of a fragment of a polypeptide chain, stabilized by hydrogen bonds.

Tertiary structure is the spatial structure of the polypeptide chain (a set of spatial coordinates of the atoms that make up the protein). Structurally, it consists of secondary structure elements stabilized by various types of interactions, in which hydrophobic interactions play a critical role. The following take part in stabilizing the tertiary structure:

covalent bonds (between two cysteine ​​residues - disulfide bridges);

ionic bonds between oppositely charged side groups of amino acid residues;

hydrogen bonds;

hydrophilic-hydrophobic interactions. When interacting with surrounding water molecules, the protein molecule “tends” to fold so that the nonpolar side groups of amino acids are isolated from the aqueous solution; polar hydrophilic side groups appear on the surface of the molecule.

Quaternary structure (or subunit, domain) - the relative arrangement of several polypeptide chains as part of a single protein complex. Protein molecules that make up a protein with a quaternary structure are formed separately on ribosomes and only after completion of synthesis form a common supramolecular structure. A protein with a quaternary structure can contain both identical and different polypeptide chains. The same types of interactions take part in the stabilization of the quaternary structure as in the stabilization of the tertiary structure. Supramolecular protein complexes can consist of dozens of molecules.

Physical properties

The properties of proteins are as varied as the functions they perform. Some proteins dissolve in water, usually forming colloidal solutions (for example, egg white); others dissolve in dilute salt solutions; still others are insoluble (for example, proteins of integumentary tissues).

Chemical properties

In the radicals of amino acid residues, proteins contain various functional groups that are capable of participating in many reactions. Proteins undergo oxidation-reduction reactions, esterification, alkylation, nitration, and can form salts with both acids and bases (proteins are amphoteric).

For example, albumin - egg white - at a temperature of 60-70° precipitates from solution (coagulates), losing its ability to dissolve in water.

LECTURE TOPIC: AMINES AND AMINO ALCOHOLS

Questions:

General characteristics: structure, classification, nomenclature.

Receipt methods

Physical properties

Chemical properties

Individual representatives. Methods of identification.

General characteristics: structure, classification, nomenclature

Amines are derivatives of ammonia in the molecule of which the hydrogen atoms are replaced by hydrocarbon radicals.

Classification

1– Amines are distinguished depending on the number of substituted hydrogen atoms of ammonia:

– primary contain an 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

Compounds with a quaternary nitrogen atom are also known: quaternary ammonium hydroxide and its salts.

2– Depending on the structure of the radical, amines are distinguished:

– aliphatic (saturated and unsaturated)

– alicyclic

– aromatic (containing an amino group or side chain in the core)

– heterocyclic.

Nomenclature, isomerism of amines

1. According to rational nomenclature, the names of amines are usually derived from the names of their constituent hydrocarbon radicals with the addition of the ending -amine : methylamine CH 3 –NH 2, dimethylamine CH 3 –NH–CH 3, trimethylamine (CH 3) 3 N, propylamine CH 3 CH 2 CH 2 –NH 2, phenylamine C 6 H 5 – NH 2, etc.

2. According to IUPAC nomenclature, the amino group is considered as a functional group and its name amino placed before the name of the main chain:

The isomerism of amines depends on the isomerism of radicals.

Methods for producing amines

Amines can be prepared in a variety of ways.

A) Action on ammonia by haloalkyls

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

B) Catalytic hydrogenation of nitrobenzene with molecular hydrogen:

C 6 H 5 NO 2 ––® C 6 H 5 NH 2 + H 2 O

nitrobenzene cat aniline

B) Preparation of lower amines (C 1 – C 4) by alkylation with 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

Methylamine, dimethylamine and trimethylamine are gases, the middle members of the series of amines are liquids, and the higher members are solids. As the molecular weight of amines increases, their density increases, their boiling point increases, and their solubility in water decreases. Higher amines are insoluble in water. Lower amines have an unpleasant odor, somewhat reminiscent of the smell of spoiled fish. Higher amines are either odorless or have a very slight odor. Aromatic amines are colorless liquids or solids that have an unpleasant odor and are poisonous.

Chemical properties of amines

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

The presence of a free electron pair on the nitrogen atom gives it the opportunity to attach a proton, therefore amines are similar to ammonia, exhibit basic properties, form hydroxides and salts.

Salt formation. Amines with acids give salts, which, under the influence of a strong base, again give free amines:

Amines give salts even with weak carbonic acid:

Like ammonia, amines have basic properties due to the binding of protons into a weakly dissociating substituted ammonium cation:

When an amine is dissolved in water, part of the water's protons is consumed to form a cation; Thus, an excess of hydroxide ions appears in the solution, and it has alkaline properties sufficient to color solutions of litmus blue and phenolphthalein crimson. The basicity of the amines of the limiting series varies within very small limits and is close to the basicity of ammonia.

The effect of methyl groups slightly increases the basicity of methyl and dimethylamine. In the case of trimethylamine, methyl groups already hinder the solvation of the resulting cation and reduce its stabilization, and therefore its basicity.

Amine salts should be considered as complex compounds. The central atom in them is a nitrogen atom, the coordination number of which is four. Hydrogen or alkyl atoms are bonded to the nitrogen atom and are located in the inner sphere; the acid residue is located in the outer sphere.

Acylation of amines. When some derivatives of organic acids (acid halides, anhydrides, etc.) act on primary and secondary amines, amides are formed:

Secondary amines with nitrous acid give nitrosamines- yellowish liquids, slightly soluble in water:

Tertiary amines are resistant to the action of dilute nitrous acid in the cold (they form salts of nitrous acid); under more severe conditions, one of the radicals is split off and nitrosoamine is formed.

Diamines

Diamines play an important role in biological processes. As a rule, they are easily soluble in water, have a characteristic odor, have a highly alkaline reaction, and interact with CO 2 in the air. Diamines form stable salts with two equivalents of acid.

Ethylenediamine (1,2-ethanediamine) H 2 NCH 2 CH 2 NH 2 . It is the simplest diamine; can be obtained by the action of ammonia on ethylene bromide:

Tetramethylenediamine (1,4-butanediamine), or putrescine, NH 2 CH 2 CH 2 CH 2 CH 2 NH 2 and pentamethylenediamine (1,5-pentanediamine) NH 2 CH 2 CH 2 CH 2 CH 2 CH 2 NH 2, or cadaverine. They were discovered in the decomposition products of protein substances; are formed by decarboxylation of diamino acids and are called ptomaines(from Greek - corpse), they were previously considered “cadaveric poisons”. It has now been found that the toxicity of rotting proteins is not caused by ptomains, but by the presence of other substances.

Putrescine and cadaverine are formed as a result of the vital activity of many microorganisms (for example, the causative agents of tetanus and cholera) and fungi; they are found in cheese, ergot, fly agaric, and brewer's yeast.

Some diamines are used as raw materials for the production of polyamide fibers and plastics. Thus, from hexa-methylenediamine NH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 NH 2 a very valuable synthetic fiber was obtained - nylon(USA) or anid(Russia).

Amino alcohols

Amino alcohols- compounds with mixed functions, the molecule of which contains amino and hydroxy groups.

Aminoethanol(ethanolamine) HO-CH 2 CH 2 -NH 2, or colamine.

Ethanolamine is a thick oily liquid, miscible with water in all respects, and has strong alkaline properties. Along with monoethanolamine, diethanolamine and triethanolamine are also obtained:

Choline is included in lecithins- fat-like substances, very common in animal and plant organisms, and can be isolated from them. Choline is a crystalline, highly hygroscopic mass that easily dissolves in air. It has strong alkaline properties and easily forms salts with acids.

When choline is acylated with acetic anhydride, it forms choline acetate, also called acetylcholine:

Acetylcholine plays an extremely important biochemical role, as it is a mediator (mediator) that transmits excitation from nerve receptors to muscles.

Amines- organic derivatives of ammonia, in the molecule of which one, two or all three hydrogen atoms are replaced by a carbon residue.

There are usually 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 lone electron pair at the nitrogen atom included in the functional group. 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 of amines

1. Amines are characterized by structural isomerism:

A) carbon skeleton isomerism:

b) isomerism of the position of the functional group:

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) are gaseous substances. The remaining lower amines are 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.

Chemical properties of amines

The chemical properties of amines are determined mainly by the presence of a lone electron pair on the nitrogen atom.

Amines as bases. The nitrogen atom of the amino group, like the nitrogen atom in the ammonia molecule, due to a lone pair of electrons, can form a covalent bond according to 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:

2. Reaction with acids. Ammonia reacts with acids to form ammonium salts. Amines are also capable of reacting with acids:

The 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:

Amion combustion. Amines burn in air to form carbon dioxide, water and nitrogen:

Application of amines

Amines are widely used to produce drugs and 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).