What organic compounds contain nitrogen. Ethylamine ethyl ammonium chloride
Amines. These organic compounds are derivatives of ammonia. They can be considered as products of substitution of one, two or three hydrogen atoms in the ammonia molecule by hydrocarbon radicals:
H ─ N: CH 3 ─ N: CH 3 ─ N: CH 3 ─ N:
ammonia methylamine dimethylamine trimethylamine
Amines are organic bases. Due to the lone pair of electrons at the nitrogen atom, their molecules, like the ammonia molecule, can attach protons:
CH 3 ─ N: + Н─О─Н → CH 3 ─ N─Н OH -
methylammonium hydroxide
Amino acids and proteins
are of great biological importance amino acids- compounds with mixed functions, which, as in amines, contain amino groups ─ NH 2 and at the same time, as in acids, carboxyl groups ─ COOH.
The structure of amino acids is expressed by the general formula (where R is a hydrocarbon radical, which may contain various functional groups):
H 2 N─CH ─ C─OH
H 2 N─CH 2 ─ C─OH H 2 N─CH ─ C─OH
glycine alanine
Amino acids are amphoteric compounds: they form salts with bases (due to the carboxyl group) and with acids (due to the amino group).
The hydrogen ion, split off during dissociation from the amino acid carboxyl, can pass to its amino group with the formation of an ammonium group. thus, amino acids exist and react also in the form of bipolar ions (internal salts):
H 2 N─CH ─ COOH ↔ H 3 N + ─CH ─ COO -
amino acid bipolar ion
(internal salt)
This explains that solutions of amino acids containing one carboxyl and one amino group have a neutral reaction.
Molecules of protein substances, or proteins, are built from amino acid molecules, which, when completely hydrolyzed under the influence of mineral acids, alkalis or enzymes, decompose, forming mixtures of amino acids.
Squirrels- natural high-molecular nitrogen-containing organic compounds. They play a primary role in all life processes, they are carriers of life.
Proteins are made up of carbon, hydrogen, oxygen, nitrogen, and often sulfur, phosphorus, and iron. The molecular weights of proteins are very large - from 1500 to several million.
The structure of a protein molecule can be represented as follows:
R R′ R R" R"′
│ │ │ │ │
H 2 N─CH ─ C─... НN─CH ─ C─.... НN─CH ─ C─... НN─CH ─ C─.... НN─CH ─ C─OH
║ ║ ║ ║ ║
In protein molecules, groups of atoms ─СО─NH─ are repeated many times; they are called amide groups, or in protein chemistry - peptide groups.
Tasks, control questions
1. How many m 3 of carbon monoxide (IV) is formed during combustion: a) 5 m 3 of ethane; b) 5 kg of ethane (n.o.s.)?
2. Write the structural formulas of normal alkenes containing: a) four; b) five; c) six carbon atoms.
3. Write the structural formula of n-propanol.
4. What compounds are carbonyl? Give examples, write structural formulas and indicate the carbonyl group in them.
5. What are carbohydrates? Give examples.
The most important organic and inorganic polymers,
their structure and classification
High molecular weight compounds, or polymers, are called complex substances with large molecular weights (of the order of hundreds, thousands, millions), the molecules of which are built from many repeating elementary units, formed as a result of the interaction and combination with each other of the same or different simple molecules - monomers.
Oligomer- a molecule in the form of a chain of a small number of identical constituent units. This distinguishes oligomers from polymers, in which the number of units is theoretically unlimited. The upper limit of the mass of an oligomer depends on its chemical properties. The properties of oligomers are highly dependent on changes in the number of repeating units in the molecule and the nature of the end groups; from the moment when the chemical properties cease to change with increasing chain length, the substance is called a polymer.
Monomer- a substance consisting of molecules, each of which can form one or more constituent units.
Composite link- an atom or a group of atoms that make up the chain of an oligomer or polymer molecule.
Degree of polymerization- the number of monomer units in the macromolecule.
Molecular mass is an important characteristic of macromolecular compounds - polymers, which determines their physical (and technological) properties. The number of monomeric units that make up different molecules of the same polymeric substance is different, as a result of which the molecular weight of polymer macromolecules is also not the same. Therefore, when characterizing a polymer, one speaks of the average value of the molecular weight. Depending on the method of averaging - the principle underlying the method for determining the molecular weight, there are three main types of molecular weights.
Number average molecular weight- averaging over the number of macromolecules in the polymer:
v i-number fraction of macromolecules with molecular weight M i , N- number of fractions
Weight average molecular weight- averaging over the mass of molecules in the polymer:
Where w i- mass fraction of molecules with molecular weight Mi.
Molecular weight distribution (MWD) of the polymer (or its polydispersity) - is its most important characteristic and is determined by the ratio of the quantities n i macromolecules with different molecular weights M i in this polymer. MWD has a significant effect on the physical characteristics of polymers, and, above all, on the mechanical properties.
MWD characterize the numerical and mass fraction of macromolecules whose molecular weights (M) lie in the range from M before M+dM. Determine the numerical and mass differential functions of the MMP:
dN M- the number of macromolecules in the interval dM;
dm M- mass of macromolecules in the interval dM;
N0- the total number of macromolecules in a sample with a mass m0.
For a quantitative comparison of the MWD of various polymers, the ratios of the average values of their molecular weights are used.
Classification of polymers
By origin, polymers are divided into:
natural (biopolymers), e.g. proteins, nucleic acids, natural resins,
and synthetic eg polyethylene, polypropylene, phenol-formaldehyde resins.
Atoms or atomic groups can be arranged in a macromolecule in the form:
an open chain or a sequence of cycles stretched into a line ( linear polymers e.g. natural rubber);
branched chains ( branched polymers such as amylopectin)
3D grid ( crosslinked polymers, network, or spatial, are called polymers built from long chains connected to each other in a three-dimensional grid by transverse chemical bonds; e.g. cured epoxy resins). Polymers whose molecules consist of identical monomeric units are called homopolymers(e.g. polyvinyl chloride, polycaproamide, cellulose).
Macromolecules of the same chemical composition can be built from units of different spatial configurations. If macromolecules consist of the same stereoisomers or of different stereoisomers alternating in a chain at a certain periodicity, polymers are called stereoregular.
Polymers whose macromolecules contain several types of monomer units are called copolymers.
Copolymers in which links of each type form sufficiently long continuous sequences that replace each other within the macromolecule are called block copolymers.
One or more chains of another structure can be attached to the internal (non-terminal) links of a macromolecule of one chemical structure. Such copolymers are called vaccinated.
Polymers in which each or some of the stereoisomers of the link form sufficiently long continuous sequences that replace each other within one macromolecule are called stereoblock copolymers.
Depending on the composition of the main (main) chain, polymers are divided into: heterochain, the main chain of which contains atoms of various elements, most often carbon, nitrogen, silicon, phosphorus,
and homochain, the main chains of which are built from identical atoms.
Of the homochain polymers, the most common are carbon chain polymers, the main chains of which consist only of carbon atoms, for example, polyethylene, polymethyl methacrylate, polytetrafluoroethylene.
Examples of heterochain polymers are polyesters (polyethylene terephthalate, polycarbonates), polyamides, urea-formaldehyde resins, proteins, some organosilicon polymers.
Polymers whose macromolecules, along with hydrocarbon groups, contain atoms of inorganic elements are called organoelement. A separate group of polymers is formed by inorganic polymers, such as plastic sulfur, polyphosphonitrile chloride.
The most important natural and artificial polymers. Biopolymers.
Examples of natural macromolecular compounds (biopolymers) are starch and cellulose, built from elementary units, which are monosaccharide (glucose) residues, as well as proteins, whose elementary units are amino acid residues; this also includes natural rubbers.
Currently, a huge number of artificial polymers have been created. On the basis of them receive plastics (plastics) - complex compositions into which various fillers and additives are introduced that give the polymers the necessary set of technical properties - as well as synthetic fibers and resins.
Polyethylene- a polymer formed during the polymerization of ethylene, for example, by compressing it to 150-250 MPa at 150-200 0 C (high pressure polyethylene)
CH 2 \u003d CH 2 + CH 2 \u003d CH 2 + CH 2 \u003d CH 2 → ... ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─ ...
polyethylene
or n CH 2 \u003d CH 2 → (─ CH 2 ─ CH 2 ─) n
Polyethylene is a saturated hydrocarbon with a molecular weight of 10,000 to 400,000. It is a colorless translucent in thin and white in thick layers, a waxy but solid material with a melting point of 110-125 0 C. It has high chemical resistance and water resistance, low gas permeability .
Polypropylene- propylene polymer
n
CH 3 CH 3 CH 3
propylene polypropylene
Depending on the polymerization conditions, polypropylene is obtained, which differs in the structure of macromolecules, a. hence, properties. In appearance, it is a rubber-like mass, more or less hard and elastic. Differs from polyethylene in higher melting point.
Polystyrene
n CH 2 \u003d CH → ─CH 2 ─CH─CH 2 ─CH─
C 6 H 5 C 6 H 5 C 6 H 5
styrene polystyrene
PVC
n CH 2 \u003d CH → ─CH 2 ─CH─CH 2 ─CH─
vinyl chloride polyvinyl chloride
It is an elastic mass, very resistant to acids and alkalis.
Polytetrafluoroethylene
n CF 2 \u003d C F 2 → (─ CF─CF─) n
tetrafluoroethylene polytetrafluoroethylene
Polytetrafluoroethylene comes in the form of a plastic called Teflon, or PTFE. It is very resistant to alkalis and concentrated acids, surpasses gold and platinum in chemical resistance. Non-flammable, has high dielectric properties.
Rubbers- elastic materials, from which rubber is obtained by special processing.
Natural (natural) rubber is a high-molecular unsaturated hydrocarbon, the molecules of which contain a large number of double bonds, its composition can be expressed by the formula (C 6 H 8) n(where the value n ranges from 1000 to 3000); it is a polymer of isoprene:
n CH 2 \u003d C ─ CH \u003d CH 2 → ─ CH 2 ─ C \u003d CH ─ CH 2 ─
CH 3 CH 3 n
natural rubber (polyisoprene)
Many different types of synthetic rubbers are currently being produced. The first synthesized rubber (the method was proposed by S.V. Lebedev in 1928) is polybutadiene rubber:
n CH 2 = CH─CH=CH 2 → (─CH 2 ─CH=CH─CH 2 ─) n
Amines called derivatives of ammonia NH 3, in the molecule of which one or more hydrogen atoms are replaced by hydrocarbon residues.
Amines can also be considered as derivatives of hydrocarbons formed by replacing hydrogen atoms in hydrocarbons with groups
NH 2 (primary amine); NHR(secondary amine); NR" R" (tertiary amine).
Depending on the number of hydrogen atoms at the nitrogen atom, substituted by radicals, amines are called primary, secondary or tertiary.
The group - NH 2, which is part of the primary amines, is called amino group. Group >NH in secondary amines is called imino group.
Amine nomenclature
Usually amines are called by those radicals that are included in their molecule, with the addition of the word amine.
CH 3 NH 2 - methylamine; (CH 3) 2 NH - dimethylamine; (CH 3) 3 N - trimethylamine.
Aromatic amines have specific nomenclature.
C 6 H 5 NH 2 – phenylamine or aniline.
Physical properties of amines
The first representatives of amines - methylamine, dimethylamine, trimethylamine - are gaseous substances at ordinary temperature. The remaining lower amines are liquids. Higher amines are solids.
The first representatives, like ammonia, dissolve in water in large quantities; higher amines are insoluble in water.
The lower representatives have a strong smell. Methylamine CH 3 NH 2 is found in some plants and smells like ammonia; trimethylamine in a concentrated state has an odor similar to that of ammonia, but in the low concentrations that are commonly encountered, it has a very unpleasant smell of rotten fish.
Trimethylamine (CH 3) 3 N is contained in fairly large quantities in herring brine, as well as in a number of plants, for example, in the flowers of one species of hawthorn.
Diamines- This is a group of compounds that can be considered as hydrocarbons, in the molecules of which two hydrogen atoms are replaced by amino groups (NH 2).
Putrescine was first found in pus. It is tetramethylenediamine:
H 2 C - CH 2 - CH 2 - CH 2
tetramethylenediamine
Cadaverine, a homologue of putrescine, has been found in decaying corpses (cadaver - corpse), it is pentamethylenediamine:
H 2 C - CH 2 - CH 2 - CH 2 - CH 2
pentamethylenediamine
Putrescine and cadaverine are formed from amino acids during the decay of protein substances. Both substances are strong bases.
Organic bases formed during the decay of corpses (including putrescine and cadaverine) are united by the common name ptomains. Ptomains are poisonous.
The next representative of diamines - hexamethylenediamine - is used to obtain a valuable synthetic fiber - nylon.
H 2 C - CH 2 - CH 2 - CH 2 - CH 2 - CH 2
hexamethylenediamine
Methods for obtaining amines
1. The action of ammonia on alkyl halides (halohydrocarbons) - the Hoffmann reaction.
Initial reaction:
CH 3 I + NH 3 \u003d I
I + NH 3 CH 3 NH 2 + NH 4 I
methylamine
CH 3 NH 2 + CH 3 I [(CH 3) 2 NH 2] I
dimethylammonium iodide
[(CH 3) 2 NH 2] I + NH 3 (CH 3) 2 NH + NH 4 I
dimethylamine
(CH 3) 2 NH + CH 3 I [(CH 3) 3 NH] I
trimethylammonium iodide
[(CH 3) 3 NH] I + NH 3 (CH 3) 3 N + NH 4 I
trimethylamine
(CH 3) 3 N + CH 3 I [(CH 3) 4 N] I
tetramethylammonium iodide -
tetra-ammonium salt
The starting methylamine can also be obtained as follows:
I + NaOH \u003d CH 3 NH 2 + NaI + H 2 O
methylamine
As a result of these reactions, a mixture of substituted ammonium salts is obtained (it is impossible to stop the reaction at the first stages).
Such a reaction makes it possible to obtain the so-called invert soaps, soaps that are used in an acidic environment.
(CH 3) 3 N+ C 16 H 33 Cl [(CH 3) 3 NC 16 H 33] Cl
trimethylcetylammonium chloride
The washing effect here is not an anion, as in conventional soaps, but a cation. The peculiarity of this soap is that they are used in an acidic environment.
Such soaps do not dry the skin, which, as you know, has an acidic environment with
A substituent exhibiting antimicrobial activity can be introduced into the structure of an invert soap. In this case, bactericidal soaps used in surgical practice are synthesized.
2. Recovery of nitro compounds (nickel catalyst)
CH 3 NO 2 + 3H 2 \u003d CH 3 NH 2 + 2H 2 O
3. Under natural conditions, aliphatic amines are formed as a result of putrefactive bacterial processes of decomposition of nitrogenous substances - primarily during the decomposition of amino acids formed from proteins. Such processes occur in the intestines of humans and animals.
Chemical properties of amines
1. Interaction with acids
Amine + acid = salt
The reaction is similar to the reaction of the formation of ammonium salts:
NH 3 + HCl \u003d NH 4 Cl
ammonia ammonium chloride
CH 3 NH 2 + HCl \u003d Cl
methylamine methylammonium chloride
2. Reaction with nitrous acid
This reaction makes it possible to distinguish between primary, secondary and tertiary aliphatic, as well as aromatic amines, because they relate differently to the action of nitrous acid.
Nitrous acid is used at the time of isolation by the reaction of dilute hydrochloric acid with sodium nitrite, carried out in the cold:
NaNO 2 (tv) + HCl (aq) NaCl (aq) + HON \u003d O (aq)
Amines are organic derivatives of ammonia NH 3, in the molecule of which one, two or three hydrogen atoms are replaced by hydrocarbon radicals:
The simplest representative is methylamine:
Classification. Amines are classified according to two structural features:
- according to the number of radicals associated with the nitrogen atom, they distinguish: primary (one radical), secondary (two radicals), tertiary (three radicals) (Table 7.2);
- by the nature of the hydrocarbon radical, amines are divided into aliphatic (fatty) - derivatives of alkanes, aromatic and mixed (or fatty aromatic).
Table 7.2
Amine nomenclature. The names of most amines are formed from the names of the hydrocarbon radical (radicals in ascending order) and the suffix -amine. Primary amines are also 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:
Amino acids are compounds whose molecules contain both amino and carboxyl groups. Their simplest representative is aminoacetic acid (glycine):
An amino acid molecule may contain several carboxyl or amino groups, as well as other functional groups. Depending on the position of the amino group with respect to the carboxyl, alpha-(a), betta-(R), gamma-(y), delta-(E), elsmlol-amino acids (e), etc.:
2-aminopropanoic acid (cc-aminopropinoic, alanine);
Alpha-amino acids play an important role in the life processes of living organisms, as they are the compounds from which any protein molecule is built. All a-amino acids that are often found in living organisms have trivial names, which are usually used. (Representatives of some alpha-amino acids are shown in Table 7.3.)
Table 7.3
Amino acids are crystalline solids with a high melting point that decompose when melted. Highly soluble in water, aqueous solutions are electrically conductive. The most important chemical property of amino acids is the intermolecular interaction of a-amino acids, which leads to the formation of peptides. When two a-amino acids interact, a dipeptide is formed. The intermolecular interaction of three a-amino acids leads to the formation of a tripeptide, and so on. Fragments of amino acid molecules that form a peptide chain are called amino acid residues, and the CO-NH bond is called a peptide bond.
Amino acids are used in many areas. They are used as food additives. So, vegetable proteins are enriched with lysine, tryptophan and threonine, and methionine is included in soy dishes. In food production, amino acids are used as flavor enhancers and additives. Due to the pronounced meat taste, the L-enantiomer of the monosodium salt of glutamic acid is widely used. Glycine is added as a sweetener, bacteriostatic agent and antioxidant. Being not only structural elements of proteins and other endogenous compounds, amino acids are of great functional importance, some of them act as neurotransmitter substances, others have found independent use as medicines. Amino acids are used in medicine as parenteral (i.e., bypassing the gastrointestinal tract) nutrition of patients with diseases of the digestive and other organs. They are also used to treat liver diseases, anemia, burns (methionine), stomach ulcers (histidine), neuropsychiatric diseases (glutamic acid, etc.). Amino acids are used in animal husbandry and veterinary medicine for animal nutrition and treatment, as well as in the microbiological and chemical industries.
Lecture:Characteristic chemical properties of nitrogen-containing organic compounds: amines and amino acids
Amines, features of their structure
You already know that organic molecules are made up of carbon, hydrogen, and oxygen atoms. But among them there are those that contain nitrogen atoms. It is nitrogen-containing organic compounds, such as amino acids, proteins and nucleic acids, that are the basis of life on Earth. The simplest nitrogen-containing compounds are amines.
Amines- These are organic compounds that are derivatives of ammonia, in the molecule of which one or more hydrogen atoms are replaced by hydrocarbon radicals (R).
Based on this statement, i.e. according to the number of amino groups NH 2 amines are divided into:
primary,
secondary and
tertiary.
The nitrogen atom in the amine molecule is always ready to donate its lone electron pair to another atom, so it is a donor. Thus, the bond of the hydrogen cation with the nitrogen atom in the amine molecule occurs via the donor-acceptor mechanism. Based on this, amines, like ammonia, have fairly pronounced basic properties.
Depending on the type of radical associated with the nitrogen atom, amines are divided into:
aliphatic (CH 3 -N<) и
aromatic (C 6 H 5 -N<).
Isomerism of aliphatic amines:
Aliphatic amines, otherwise called limiting, are stronger bases than ammonia. This is due to the fact that hydrocarbon substituents in amines have a positive inductive (+I) effect. Also, because of this, the electron density on the nitrogen atom increases. This process significantly facilitates its interaction with the H+ cation.
Isomerism of aromatic amines:
Aromatic amines exhibit weaker basic properties compared to ammonia. This is explained by the fact that the lone electron pair of the nitrogen atom is shifted towards the aromatic π-system of the benzene ring. Subsequently, the electron density on the nitrogen atom gradually decreases.
Chemical properties of amines
The presence of an electron pair on the nitrogen atom gives amines basic properties. Primary limiting amines, due to their stronger basic properties, interact with water somewhat better than ammonia. In turn, the basicity of the secondary limiting amines is greater than the primary ones. The manifestation of the basic properties of tertiary amines is not so clear, because the nitrogen atom in them is often shielded by hydrocarbon radicals, which prevents the manifestation of its basic properties.
Amines enter into reversible reactions with water. The aqueous solution of amines is an alkaline environment, which is a consequence of the dissociation of the resulting bases. The general form of the reaction is as follows:
RNH 2 + H 2 O<->RNH3 + +OH -
Free saturated amines and their aqueous solutions interact with acids to form salts. For example:
CH 3 NH 2 + H 2 SO 4 → HSO 4
C 6 H 5 NH 2 + HCl → Cl
Amine salts are analogues of ammonium salts and are solids. They dissolve well in water and poorly in non-polar organic solvents. In reactions with alkalis, when heated, free amines are released from amine salts:
[CH3NH3] Cl + NaOH → CH 3 NH 2 + Na Cl + H2O
Primary saturated amines interact with nitrous acid to form alcohols, gaseous nitrogen N 2 and water:
RNH2 + HNO2 → ROH + N 2 + H 2 O
This is a qualitative reaction of primary limiting amines and is used to distinguish them from secondary and tertiary.
Secondary amines in the same reaction form oily liquids with a smell - N-nitrosamines:
R2NH+HO- N=O → R2 N-N=O+ H2O
Tertiary amines do not react with nitrous acid.
- Amines enter into nucleophilic substitution reactions:
CH 3 CH 2 Br + CH 3 CH 2 NH2 → (CH 3 CH 2 ) 2 NH2+ br- CH 2 CH 3
- The interaction of primary and secondary amines with carboxylic acids leads to their acylation, resulting in the formation of the most important organic compounds amides:
Complete combustion of any amines leads to the formation of carbon dioxide, water and nitrogen:
4C n H 2n+3 N + (6n+3)O 2 → 4nCO 2 + (4n+6)H 2 O
Consider the characteristic chemical properties of aniline (aminobenzene) - the simplest aromatic amine. The amino group in the molecule of this substance is directly connected to the aromatic ring. The basic properties of aniline are much weaker than aliphatic amines. Therefore, the reaction of aniline with water and weak acids (for example, carbonic) does not go.
Aniline reacts with strong and medium inorganic acids to form phenylammonium. For example:
C 6 H 5 N H 2 + HCl → C 6 H 5 N H 3 C l
Salts of phenylammonium C 6 H 5 NH 3 + are highly soluble in water, but insoluble in non-polar organic solvents.
The amino group of aromatic amines, in particular aniline, drawn into the aromatic ring reduces the electron density on the nitrogen atom, but increases it in the aromatic nucleus. Therefore, electrophilic substitution reactions (with halogens) proceed much more easily, especially in the ortho and para positions. For example, aniline easily reacts with bromine water, forming a white precipitate of 2,4,6-tribromoaniline:
This is a qualitative reaction to aniline.
Aniline reacts with nitrous acid at t 0 0 C, diazonium salts are formed, which are of great practical importance and are used for the synthesis of azo dyes and other compounds:
C 6 H 5 NH 2 + KNO 2 + 2HCl → + Cl - + KCl + 2H 2 O
The products of this reaction are phenyldiazonium chloride, potassium chloride and water.
When this type of reaction is carried out at high t, nitrogen is released, and aniline is converted to phenol:
C 6 H 5 NH 2 + NaNO 2 + H 2 SO 4 → C 6 H 5 -OH + N 2 + Na HSO 4 + H2O
Alkylation of aniline with halogen derivatives of hydrocarbons forms secondary and tertiary amines.
Chemical properties of amino acids
Amino acids- organic compounds, the molecules of which have two functional groups - amino (-NH 2) and carboxy- (-COOH).
The general formula of amino acids: (NH2)xR(COOH)y, where x and y are most often 1 or 2.
The presence of amino and carboxy groups in the molecules of these compounds explains the chemical properties of amino acids, similar to amines and carboxylic acids. Therefore, amino acids exhibit basic properties characteristic of compounds containing amino groups and acidic properties characteristic of compounds containing a carboxyl group. Therefore, amino acids are amphoteric organic compounds.
- In reactions with alkalis, amino acids exhibit acidic properties:
H 2 N-CH 2 -COOH + NaOH → H 2 N-CH 2 -COOH - Na ++ H2O
- In esterification reactions with alcohols, they also exhibit acidic properties:
NH 2 CH 2 COOH + CH 3 OH → NH 2 CH 2 COOCH 3 + H 2 O
In reactions with strong acids, they show the main properties:
NH 2 CH 2 COOH + HCl → + Cl -
The reaction with nitrous acid proceeds as in the case of primary amines:
NH 2 -CH 2 -COOH + HNO 2 → HO-CH 2 -COOH + N 2 + H 2 O
Amino acid alkylation:
NH 2 CH 2 COOH + CH 3 I → + I -
In reactions with each other, amino acids form dipeptides - compounds containing a peptide bond -C (O) -NH - in their molecules. For example, in the reaction of glycine and alanine, the dipeptide glycylalanine is formed:
Carrying out this reaction without observing the specific synthesis conditions will lead to the formation of not glycylalanine, but alanylglycine.
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CLASSIFICATION This group of compounds includes several classes: Amines Amides Imides Azo compounds Diazo compounds. Amino acids Nitro compounds Nitroso compounds
AMINES Amines can be considered as derivatives of ammonia. Amines are organic compounds that are obtained by replacing hydrogen atoms in ammonia with hydrocarbon radicals.
o CLASSIFICATIONS Depending on the number of hydrogen atoms in the ammonia molecule substituted by hydrocarbon radicals, amines are divided into: Primary Secondary Tertiary
According to the type of radicals, amines are divided into: § Limit; § Unlimited; § Aromatic. According to the number of amino groups, amines are divided into: § Monoamines; § Diamines; § Polyamines.
o NOMENCLATURE Universal. The name of the amine is built from two words: the names of hydrocarbon radicals according to the radical nomenclature and the word "amine". Rational. It is used to construct the names of primary amines only. It is based on the name of the hydrocarbon and the prefix "amino-" before which the number indicates the position of the amino group. Sometimes the suffix "amine" is used instead of the prefix.
Primary amines Methylamine Aminomethane Metalamine Ethylamine Aminoethane Propylamine 1-aminopropane Isopropylamine 2-aminopropane Propylamine-2 sec. propylamine Butylamine 1-aminobutane
Deut. butylamine 2-aminobutane Isobutylamine 2-methyl-1-aminopropane aminoisobutane Tret. butylamine 2 -methyl-2 -aminopropane 2 -methylpropylamine-2 Secondary amines Dimethylamine Methylethylamine
o PHYSICAL PROPERTIES Methylamine, dimethylamine, trimethylamine are gases. The remaining lower amines are liquids. Higher amines are solids. Amines have an unpleasant “herring pickle” odor, which is more pronounced in the lower ones, and weaker (or absent) in the higher ones. Lower amines (the first representatives) are quite soluble in water (like ammonia), their solutions have the main reaction of the medium.
o METHODS OF OBTAINING In 1850, the German scientist Hoffmann first obtained an amine as a result of a chemical reaction of the interaction of a halogenated hydrocarbon with an excess of ammonia. An excess of ammonia is needed to obtain pure amine. With a lack of ammonia, a mixture is always formed.
Primary amines are the most biologically active. They were obtained by decomposition of acid amides (Hoffmann rearrangement). Propionic acid amide This method is widely used in laboratory practice.
In industry, primary amines are obtained by reduction of nitro compounds and acid nitriles. nitroethane propionic acid nitrile ethylamine propylamine
Interaction with nitrous acid When primary amines react with nitrous acid, primary alcohols are formed.
Secondary amines react with nitrous acid to form nitrosamines (yellow-orange colored compounds).
Oxidation. is difficult, and the result depends on the structure. Oxidation of primary amines leads to the formation of nitro compounds.
These are compounds in the molecules of which the amino group is bonded to the benzene ring. The simplest representative and ancestor of aniline dyes is
o. PHYSICAL PROPERTIES Aniline is a colorless liquid that rapidly turns brown in air. Poorly soluble in water.
o. CHEMICAL PROPERTIES are due to both the amino group and the benzene ring. The amino group is an electron donor substituent and the properties of aniline due to the benzene ring are as follows:
interaction with alcohols - specific chemical properties of the amino group due to direct contact with the benzene ring.
UREA is a complete amide of carbonic acid. Widely distributed in nature. It is the end product of protein metabolism. Under normal conditions, urea is a solid crystalline substance that melts at a temperature of 133 C. It is readily soluble in polar and absolutely insoluble in non-polar solvents. It has weak basic properties, but they are less pronounced than those of amines due to the carbonyl group.
PRODUCTION OF UREA In industry, urea is obtained in the following ways: Interaction of full carbonic acid halide with ammonia
Biuret is the simplest organic compound with a peptide bond. The peptide bond is the main bond of all natural protein bodies. The reaction of biuret with copper(II) hydroxide is a qualitative reaction for proteins.
Amino acids are those derivatives of carboxylic acids that can be obtained by substitution of one or more hydrogen atoms in the acid radical
o CLASSIFICATIONS Depending on the number of carboxyl groups: Monobasic Dibasic Polybasic
Depending on the number of amino groups: Mono-amino acids Di-amino acids Tri-amino acids Depending on the structure of the radical: Open chain Cyclic
o UNIVERSAL NOMENCLATURE: the rules for constructing names are the same as for carboxylic acids, only with the presence, number and position of amino groups in the prefix. RATIONAL: the position of amino groups is indicated by the letters of the Greek alphabet + the word "amino" + the name of the carboxylic acid according to rational nomenclature.
o Isomerism The isomerism of the position of the amino group relative to the carboxyl group. There are α-, β-, γ-, δ-, ε-, etc. Structural isomerism Optical isomerism
o PHYSICAL PROPERTIES Amino acids are colorless crystalline substances with high melting points. Don't fly. Melt with decomposition. They dissolve well in water and are poorly soluble in organic solvents. They have optical activity.
HOMOLOGICAL SERIES 2 -aminoethane α-aminoacetic glycine 2 -aminopropane α-aminopropionic α-alanine 3 -aminopropane β-aminopropionic β-alanine 2 -aminobutane α-aminobutyric 3 -aminobutane β-aminobutyric 4 -aminobutane γ-aminobutyric
SPECIFIC PROPERTIES OF AMINO ACIDS Relation to heating of α-amino acids In the absence of mineral acids
Dibasic amino acids are capable of forming internal salts. Both are found among the products of hydrolysis of protein bodies. Aspartic acid is found in free form in animals and plants. Plays an important role in nitrogen metabolism. Forms amide - aspargine. Glutamic acid is used in the treatment of mental disorders. Forms amide - glutamine.
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α-amino acids are involved in protein synthesis. The composition of protein bodies also includes such amino acids that, in addition to amino groups, also contain other functional groups. According to their importance for the body, all amino acids are divided into: - Replaceable (synthesized in the body) - Non-replaceable (replenished only with food)
Name Formula By nomenclature trivial Convention. About. α-aminoacetic Glycine gly α-aminopropionic Alanine Ala α-aminoisovaleric Valine shaft α-aminoisocaproic Leucine ley Vtor. butyl-α-aminoacetic Isoleucine ile
α, εdiamino aproic acid lysine lys α-amino-δ guanidine arginine lerianic ARG α-amino-βoxypropionic serine sulfur α-aminoβoxybutyric threonine treonine β-thio-αaminopropionic cysteine cis
cystine α-amino-γ-methionine methylthiome butyl α-amino-β-phenylpropionic acid
PROTEINS Proteins, or protein substances, are high-molecular organic compounds, the molecules of which are built from α-amino acid residues linked by peptide bonds. The number of the latter can vary greatly and sometimes reach several thousand. The structure of proteins is very complex. Separate peptide chains or their sections can be linked by disulfide, salt or hydrogen bonds. Salt bonds are formed between free amino groups (for example, the terminal amino group located at one end of the polypeptide chain or the ε-amino group of lysine) and free carboxyl groups (the terminal carboxyl group of the chain or the free carboxyl groups of dibasic amino acids); Hydrogen bonds can occur between the oxygen atom of the carbonyl group and the hydrogen atom of the amino group, as well as due to the hydroxo groups of hydroxyamino acids and the oxygen of peptide groups.
PROTEINS There are primary, secondary, tertiary and quaternary structures of protein molecules. All proteins, regardless of which group they belong to and what functions they perform, are built from a relatively small set (usually 20) of amino acids, which are located in a different, but always strictly defined sequence for a given type of protein. Proteins are divided into proteins and proteids. Ø Proteins are simple proteins, consisting only of amino acid residues. ü Albumins - have a relatively small molecular weight, are highly soluble in water, coagulate when heated.
PROTEINS ü Globulins are insoluble in pure water, but soluble in warm 10% Na solution. Cl. ü Prolamins are slightly soluble in water, but soluble in 60÷80% aqueous ethyl alcohol. ü Glutelins are soluble only in 0.2% alkali. ü Protamines - do not contain sulfur at all. ü Proteinoids are insoluble proteins. ü Phosphoproteins - contain phosphoric acid (casein).
PROTEINS Ø Proteids are complex proteins, which, along with amino acids, include carbohydrates, lipids, heterocyclic compounds, nucleic acids, phosphoric acid. Lipoproteins are hydrolyzed into simple proteins and lipids. (chlorophyll grains, cell protoplasm). ü Glycoproteins - hydrolyzed into simple proteins and high molecular weight carbohydrates. (mucous secretions of animals). ü Chromoproteins - hydrolyzed into simple proteins and dyes (hemoglobin) ü Nucleoproteins - hydrolyzed into simple proteins (usually protamines) and nucleic acids
