Amines entered our lives quite unexpectedly. Until recently, these were poisonous substances, a collision with which could lead to death. And now, after a century and a half, we are actively using synthetic fibers, fabrics, building materials, dyes, which are based on amines. No, they did not become safer, people were simply able to "tame" them and subdue them, deriving certain benefits for themselves. About which one, and we'll talk further.

Definition

For the qualitative and quantitative determination of aniline in solutions or compounds, a reaction with is used at the end of which a white precipitate in the form of 2,4,6-tribromaniline falls on the bottom of the test tube.

Amines in nature

Amines are found in nature everywhere in the form of vitamins, hormones, metabolic intermediates, they are also found in animals and plants. In addition, when living organisms rot, medium amines are also obtained, which, in a liquid state, spread an unpleasant smell of herring brine. The "cadaveric poison" widely described in the literature appeared precisely due to the specific ambergris of amines.

For a long time, the substances we are considering were confused with ammonia due to a similar smell. But in the mid-nineteenth century, the French chemist Wurtz was able to synthesize methylamine and ethylamine and prove that they release hydrocarbons when burned. This was the fundamental difference between the mentioned compounds and ammonia.

Obtaining amines in industrial conditions

Since the nitrogen atom in amines is in the lowest oxidation state, the reduction of nitrogen-containing compounds is the simplest and most affordable way to obtain them. It is he who is widely used in industrial practice because of its cheapness.

The first method is the reduction of nitro compounds. The reaction during which aniline is formed is named by the scientist Zinin and was carried out for the first time in the middle of the nineteenth century. The second method is to reduce amides with lithium aluminum hydride. Primary amines can also be reduced from nitriles. The third option is alkylation reactions, that is, the introduction of alkyl groups into ammonia molecules.

Application of amines

By themselves, in the form of pure substances, amines are used little. One rare example is polyethylenepolyamine (PEPA), which makes epoxy resin easier to cure in the home. Basically a primary, tertiary or secondary amine is an intermediate in the production of various organics. The most popular is aniline. It is the basis of a large palette of aniline dyes. The color that will turn out at the end depends directly on the selected raw material. Pure aniline gives a blue color, while a mixture of aniline, ortho- and para-toluidine will be red.

Aliphatic amines are needed to obtain polyamides such as nylon and others. They are used in mechanical engineering, as well as in the production of ropes, fabrics and films. In addition, aliphatic diisocyanates are used in the manufacture of polyurethanes. Due to their exceptional properties (lightness, strength, elasticity and the ability to attach to any surface), they are in demand in construction (mounting foam, glue) and in the shoe industry (anti-slip soles).

Medicine is another area where amines are used. Chemistry helps to synthesize antibiotics of the sulfonamide group from them, which are successfully used as second-line drugs, that is, reserve ones. In case bacteria develop resistance to essential drugs.

Harmful effects on the human body

It is known that amines are very toxic substances. Any interaction with them can cause harm to health: inhalation of vapors, contact with open skin, or ingestion of compounds into the body. Death occurs from a lack of oxygen, since amines (in particular, aniline) bind to blood hemoglobin and prevent it from capturing oxygen molecules. Alarming symptoms are shortness of breath, blue nasolabial triangle and fingertips, tachypnea (rapid breathing), tachycardia, loss of consciousness.

In case of contact with these substances on bare areas of the body, it is necessary to quickly remove them with cotton wool previously moistened with alcohol. This must be done as carefully as possible so as not to increase the area of ​​\u200b\u200bcontamination. If symptoms of poisoning appear, you should definitely consult a doctor.

Aliphatic amines are a poison for the nervous and cardiovascular systems. They can cause depression of liver function, its degeneration and even oncological diseases of the bladder.

Ticket number 19

Task. Calculate the amount of carbon dioxide produced by burning 8 grams of methane.

1. Redox reactions (for example, the interaction of aluminum with oxides of certain metals, concentrated sulfuric acid with copper).

Redox reactions (disassemble on examples of the interaction of aluminum with iron oxide (III), nitric acid with copper).

The following types of chemical reactions can be classified as redox reactions.

Substitution reactions (displacement)

An example of reactions of this type is the reaction between iron oxide (III) and aluminum. In this reaction, aluminum displaces iron from solution, while the aluminum itself is oxidized and the iron is reduced.

Here are two more examples:

In this reaction, chlorine displaces bromine from a solution (chlorine is oxidized, bromine is reduced) containing bromine ions.

Metal reactions with acids

These reactions, in essence, are also substitution reactions. As an example, consider the reaction between copper and nitric acid. Copper displaces hydrogen from acid. In this case, copper is oxidized, which turns into a hydrated cation, and the hydrated nitrogen protons contained in the acid solution are reduced, forming nitric oxide.

Reactions of metals with water

These reactions also belong to the type of substitution reactions. They are accompanied by the displacement of hydrogen in the gaseous state from the water. As an example, here is the reaction between metallic sodium and water:

Reactions of metals with nonmetals

These reactions can be referred to as synthesis reactions. As an example, let us consider the formation of sodium chloride as a result of the combustion of sodium in an atmosphere of chlorine

2. Aniline - a representative of amines, chemical structure and properties.

The main properties of aniline: a) aromatic amine - aniline is of great practical importance; b) aniline C6H5NH2 is a colorless liquid that is poorly soluble in water; c) has a light brown color when partially oxidized in air; d) aniline is highly toxic. The main properties of aniline are weaker than those of ammonia and amines of the limiting series. 1. Aniline does not change the color of litmus, but forms salts when interacting with acids. 2. If concentrated hydrochloric acid is added to aniline, then an exothermic reaction occurs and after cooling the mixture, the formation of salt crystals can be observed: +Cl-– phenylammonium chloride. 3. If a solution of phenylammonium chloride is treated with an alkali solution, then aniline will be released again: [C6H5NH3]++ Cl-+ Na++ OH-? H2O + C6H5NH2 + Na++ CI-. Here, the influence of the aromatic radical of phenyl, C6H5, is expressed. 4. In aniline C6H5NH2, the benzene nucleus displaces the unshared electron pair of the nitrogen of the amino group towards itself. At the same time, the electron density on nitrogen decreases and it binds the hydrogen ion more weakly, which means that the properties of the substance as a base are manifested to a lesser extent. 5. The amino group affects the benzene core. 6. Bromine in aqueous solution does not react with benzene. Methods of using aniline: 1) aniline is one of the most important products of the chemical industry; 2) it is the starting material for the production of numerous aniline dyes; 3) aniline is used in the production of medicinal substances, such as sulfanilamide preparations, explosives, macromolecular compounds, etc. The discovery by Kazan University professor N.N. Zinin (1842) of an accessible method for obtaining aniline was of great importance for the development of chemistry and the chemical industry. 1. The organic synthesis industry began with the production of dyes. 2. The wide development of this production became possible on the basis of the use of the reaction for obtaining aniline, now known in chemistry under the name of the Zinin reaction. Features of the Zinin reaction: 1) this reaction consists in the reduction of nitrobenzene and is expressed by the equation: С6Н5-NO2 + 6Н? С6Н5-NH2 + 2Н2О; 2) a common industrial method for producing aniline is the reduction of nitrobenzene with metals, such as iron (cast iron shavings), in an acidic environment; 3) the reduction of nitro compounds of the corresponding structure is a common method for obtaining amines.

Lesson4 . Aniline as a representative of aromatic amines

Composition and structure, molecular and structural formulas;

Mutual influence of atoms in a molecule;

Physical properties;

Chemical properties: reactions of aniline on the amino group and aromatic nucleus.

Composition and structure, molecular and structural formulas. Aniline (aminobenzene, phenylamine) - an organic compound with the formula C 6 H 5 NH 2, consists of a benzene ring in which one hydrogen atom is replaced by an amino group. The simplest aromatic amine. Structural formula:

Aniline was first obtained in 1826 during the distillation of indigo with lime by a German chemist who gave it the name "crystallin". 1834 F. Runge discovered aniline in coal tar and named it "kyanol". 1841 Yu. F. Frishtse obtained aniline by heating indigo with a solution of KOH and named it "aniline". 1842 aniline was obtained by M. M. Zinin by the reduction of nitrobenzene (NH 4) 2 SO 3 and called it "benzydame". 1843 A. V. Hoffman established the identity of all the listed compounds. The word "aniline" comes from the name of one of the plants containing indigo.

Mutual influence of atoms in a molecule.

Influence of the amino group on the properties of the benzene ring. With respect to the ring, the amino group acts as an electron donor; injects electron density onto the ring. This excess density in the ring is mainly concentrated in positions 2,4,6 ( ortho- and core-positions):

As a result: 1) substitution reactions in the ring for aniline proceed more easily than for benzene; 2) the substituent entering the ring is directed by the amino group mainly to positions 2,4,6.

Influence of the ring on the properties of the amino group. The aromatic ring withdraws part of the electron density from the nitrogen atom, involving it in conjugation with the n-system. Therefore, the basic properties of aniline are less pronounced than those of ammonia and even more so than those of aliphatic amines. An aqueous solution of aniline does not change the color of the indicators. This is the effect of the benzene ring on the properties of the amino group.

Study of the medium of an aniline solution http://my.mail.ru/mail/ntl0000/video/29154/31055.html?related_deep=1

Physical properties. It is a colorless oily liquid with a characteristic odor, slightly heavier than water and poorly soluble in it, soluble in organic solvents. In air, it quickly oxidizes and acquires a reddish-brown color. Poisonous

Physical properties of aniline https://www.youtube.com/watch?v=2c6J-4sNGPc

Chemical properties. Be sure to watch the video .

Chemical properties https://www.youtube.com/watch?v=qQ6zqUXDJdk

Aniline, unlike benzene, easily reacts with bromine water to form a white, water-insoluble precipitate of 2,4,6-tribromaniline:

Similarly, the reaction of aniline with a solution of chlorine in CC1 4, ethanol proceeds.

Aniline practically does not react with water (very weak basic properties); the main properties of aniline are manifested in reactions with strong mineral acids:

Aniline reacts with acetic acid chloride:

When processing such salts with aqueous solutions of alkalis, aniline can be isolated:

Aniline oxidation https://www.youtube.com/watch?v=nvxipFGxTRk

The interaction of aniline with hydrochloric acid https://www.youtube.com/watch?v=VNUTpSaWQ0Q

Bromination of aniline https://www.youtube.com/watch?v=1UPJceDpelY

Aniline vapor burns in excess oxygen

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

Burning aniline https://www.youtube.com/watch?v=cYtCWMczFFs

Type of lesson: a lesson of learning new material based on existing knowledge

The purpose of the lesson: To generalize, expand and systematize the knowledge and concepts of students in the studied section "Amins". Focus on the key concepts of the topic "Aniline".

Expected result: Knowledge will be summarized and systematized with a purpose.

Lesson objectives:

Educational:

Check knowledge on the studied section, consolidate new material, deepen knowledge on the topic; summarize the studied material; check the assimilation of the material on the basis of creative tasks; to form the ability to apply the acquired knowledge in practice when performing exercises and solving problems;

Developing:

To contribute to the formation of the ability to evaluate a friend and oneself to develop the ability to express one's point of view, conduct a reasoned conversation, draw conclusions based on analysis; help students see the results of their work; to form in students the ability to highlight the main thing; develop cognitive activity and creativity.

Educational:

Cultivate an active life position, honesty, human decency; to educate students by means of a lesson self-confidence; bring students to the conclusion about the intrinsic value of human qualities.

During the classes

I Organizational and motivational stage (1 min)

The purpose of the stage (expected result): to motivate students to work actively

Stage tasks: Set students up for a high pace of the lesson

Greeting students in class. Today our lesson will be very intense, and we will face a number of tasks.

But first write down D-Z Slide 2 Homework

(diary entry)

1. § 52, § 51 repeat.

2. § 52, no. 4-6 in writing, 1-3 orally

I I Goal setting (1.5 min)

Purpose: To generalize knowledge on the passed section "Amines", to acquire knowledge on the topic of the lesson, to be able to compare aniline with other representatives of aromatic and aliphatic amines

Tasks: Slide 3 Tasks in the lesson

Recall the physical and chemical properties of amines; to continue to form the ability to compose reaction equations that characterize the properties of amines; get acquainted with the features of chemical processes in the section "Aniline"; continue to learn to see the cause of the flow of chem. reactions depending on the structure of the molecule; evaluate your work in class.

III main part. Learning new things based on known facts

The structure of amines and aniline

Learning new material based on existing knowledge

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

Accordingly, three types of amines are usually distinguished:

primary amine methylamine

CH3CH2—NH—CH2CH3

secondary amine diethylamine

H3CH2—N—CH2CH3

tertiary amine triethylamine

Amines are characterized by structural isomerism:

Isomerism of the carbon skeleton

Functional group position isomerism

Primary, secondary and tertiary amines are isomeric to each other (interclass isomerism).

Training on isomerism and amine nomenclature

Learning new material

Electronic structure of aniline

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 an unshared electron pair at the atom included in the functional group. This leads to the fact that amines exhibit the properties of bases.

There are ions that are the product of formal substitution of all hydrogen atoms in the ammonium ion for a hydrocarbon radical.

These ions are part of salts similar to ammonium salts. They are called quaternary salts.

Training on isomerism and nomenclature of aromatic amines

The study of the physical properties of aniline in comparison with the physical properties of amines

Physical properties of amines and aniline

The simplest amines (methylamine, dimethylamine, trimethylamine) are gaseous substances. The remaining lower amines are liquids that dissolve well in water. They have a characteristic smell reminiscent of the smell of ammonia.

Primary and secondary amines are capable of forming hydrogen bonds. This leads to a marked increase in their boiling points compared to compounds having the same molecular weight but incapable of forming hydrogen bonds.

Aniline is an oily liquid, sparingly soluble in water, boiling at 184°C.

Russian organic chemist, academician.

discovered (1842) the reduction reaction of aromatic nitro compounds and received aniline. He proved that amines are bases capable of forming salts with various acids. Aniline is of such great industrial importance that in just one reaction the name of this scientist can be inscribed in “golden letters in the history of chemistry.

Chemical properties of amines and aniline

The chemical properties of amines are determined mainly by the presence of an unshared electron pair at the nitrogen atom.

1. Amines as bases. The nitrogen atom of the amino group, like the nitrogen atom in the ammonia molecule, due to the 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 able to add a hydrogen cation, i.e., act as a base.

As you already know from the course, the reaction of ammonia with water leads to the formation of hydroxide ions. Ammonia solution in water is alkaline. Solutions of amines in water also give an alkaline reaction. But aniline is a weaker base and interacts reluctantly.

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

The main 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. Increasing the electron density turns nitrogen into a stronger electron pair donor, which increases its basic properties.

Similarly, aniline in reactions with acids has basic properties, but they are less pronounced than those of aliphatic amines.

In the case of aromatic amines, the amino group and the benzene ring have a significant effect on each other.

The amino group is an orientant of the first kind. The amino group has a negative inductive effect and a pronounced positive mesomeric effect. Thus, electrophilic substitution reactions (bromination, nitration) will lead to ortho- and para-substituted products.

Note that, unlike benzene, which is brominated only in the presence of a catalyst, iron(III) chloride, aniline is capable of reacting with bromine water. This is explained by the fact that the amino group, by increasing the electron density in the benzene ring (remember the similar effect of substituents in the molecules of toluene and phenol), activates the aromatic system in electrophilic substitution reactions. In addition, aniline, unlike benzene, is slightly soluble in water.

The conjugation of the p-system of the benzene ring with the lone electron pair of the amino group leads to the fact that aniline is a much weaker base than aliphatic amines.

Show the features of the reactions of complete and incomplete oxidation of amines and aniline, the mutual transition of oxidation and reduction reactions.

ALL EXAMPLES OF HRM ARE WRITTEN, THE PRODUCTS ARE NAMED (the explanation is in the form of a heuristic conversation)

Obtaining amines and aniline

1. Preparation of amines from halogen derivatives

CH3CH2Br + NH3 -> CH3CH2NH2 C6H5Br + NH3 -> C6H5NH2

2. Obtaining primary amines by the reduction of nitro compounds - aliphatic and aromatic. The reducing agent is hydrogen "at the moment of release", which is formed by the interaction of, for example, zinc with alkali or iron with hydrochloric acid.

The use of amines and aniline

Amines are widely used for the production of drugs and polymeric materials. Aniline is the most important compound of this class (scheme), which is used for the production of aniline dyes, drugs (sulfanilamide drugs), polymeric materials (aniline-formaldehyde resins), explosives, rocket fuel, pesticides.

"Active" or "reactive" dyes are the best choice of aniline dyes on the market today. This group of dyes has proven itself excellently for fabrics made from plant fibers (cotton, linen, viscose, hemp, bamboo, paper, jute, etc.).

IV Consolidation of the studied material

1. Specify the number of y-bonds in the methyl-phenyl-amine molecule:
a) 6; b) 5; at 7; d) 4.

2. What properties of aniline are explained by the influence of the phenyl radical on the amino group:

a) aniline enters into substitution reactions more easily than benzene;

b) the electron density in the aromatic ring is unevenly distributed;

c) unlike ammonia, an aqueous solution of aniline does not change the color of litmus;

d) how is the base aniline weaker than ammonia?

3. Write the graphical formulas of isomeric amines with the general molecular formula С4Н11N. Name these substances.

4. a) Get ammonium chloride from inorganic raw materials.

HC1 + KOH alcohol +HI +NH3 +HC1

b) Propanol-2 → ? →? →? →? →?

5. Find the mass of a 19.6% sulfuric acid solution that can react with 11.2 liters of methylamine (n.a.) to form a medium salt.

6. A mixture of phenol and aniline completely reacted with 480 g of bromine water with w (Br2) = 3%. 36.4 cm3 of NaOH solution (w = 10%, p = 1.2 g/cm3) was used to neutralize the reaction products. Determine the mass fractions of substances in the initial mixture.

7. Neutralization of 30 g of a mixture of benzene, phenol and aniline requires 49.7 ml of 17% HC1 (p = 1.0 g/ml). In the reaction of the same amount of the mixture with bromine water, 99.05 g of a precipitate is formed. Find the mass fractions of the components in the original mixture.

V Evaluation of class activities. Reflection.

The main properties of aniline:

a) aromatic amine - aniline is of great practical importance;

b) aniline C 6 H 5 NH 2 is a colorless liquid that is poorly soluble in water;

c) has a light brown color when partially oxidized in air;

d) aniline is highly toxic.

The main properties of aniline are weaker than those of ammonia and amines of the limiting series.

1. Aniline does not change the color of litmus, but forms salts when interacting with acids.

2. If concentrated hydrochloric acid is added to aniline, then an exothermic reaction occurs and after cooling the mixture, the formation of salt crystals can be observed: + Cl - - phenylammonium chloride.

3. If you act on a solution of phenylammonium chloride with an alkali solution, then aniline will be released again: [C 6 H 5 NH 3] + + Cl - + Na + + OH - → H 2 O + C 6 H 5 NH 2 + Na + + CI - . Here the influence of the aromatic radical of phenyl - C 6 H 5 is expressed.

4. In aniline C 6 H 5 NH 2, the benzene nucleus displaces the unshared electron pair of the nitrogen of the amino group towards itself. At the same time, the electron density on nitrogen decreases and it binds the hydrogen ion more weakly, which means that the properties of the substance as a base are manifested to a lesser extent.

5. The amino group affects the benzene core.

6. Bromine in aqueous solution does not react with benzene.

Ways to use aniline:

1) aniline- one of the most important products of the chemical industry;

2) it is the starting material for the production of numerous aniline dyes;

3) aniline is used in the production of medicinal substances, such as sulfanilamide preparations, explosives, macromolecular compounds, etc. The discovery by Kazan University professor N.N. Zinin (1842) of an accessible method for obtaining aniline was of great importance for the development of chemistry and the chemical industry.

1. The organic synthesis industry began with the production of dyes.

2. The wide development of this production became possible on the basis of the use of the reaction for obtaining aniline, now known in chemistry under the name Zinin reactions.

Features of the Zinin reaction:

1) this reaction consists in the reduction of nitrobenzene and is expressed by the equation:

C 6 H 5 -NO 2 + 6H → C 6 H 5 -NH 2 + 2H 2 O;

2) a common industrial method for producing aniline is the reduction of nitrobenzene with metals, such as iron (cast iron shavings), in an acidic environment;

3) the reduction of nitro compounds of the corresponding structure is a common method for obtaining amines.

74. Amino acids

Structure and physical properties.

1.Amino acids- these are substances whose molecules contain both the amino group NH 2 and the carboxyl group - COOH.

For example: NH 2 -CH 2 -COOH - aminoacetic acid, CH 3 -CH (NH 2) -COOH - aminopropionic acid.

2. Amino acids are colorless crystalline substances that are soluble in water.

3. Many amino acids taste sweet.

4. Amino acids can be considered as carboxylic acids, in the molecules of which the hydrogen atom in the radical is replaced by an amino group. In this case, the amino group can be located at different carbon atoms, which causes one of the types of amino acid isomerism.

Some representatives of amino acids:

1) aminoacetic acid H 2 N-CH 2 -COOH;

2) aminopropionic acid H 2 N-CH 2 -CH 2 -COOH;

3) aminobutyric acid H 2 N-CH 2 -CH 2 -CH 2 -COOH;

4) aminovaleric acid H 2 N-(CH 2) 4 -COOH;

5) aminocaproic acid H 2 N-(CH 2) 5 -COOH.

5. The more carbon atoms in an amino acid molecule, the more isomers with different positions of the amino group relative to the carboxyl group can exist.

6. In order to indicate the position of the group - NH 2 in relation to the carboxyl in the name of the isomers, the carbon atoms in the amino acid molecule are designated sequentially by the letters of the Greek alphabet: a) α-aminocaproic acid; b) β-aminocaproic acid.

Features of the structure of amino acids consist in isomerism, which can also be due to the branching of the carbon skeleton, as well as the structure of its carbon chain.

Ways to use amino acids:

1) amino acids are widely distributed in nature;

2) amino acid molecules are the building blocks of which all plant and animal proteins are built; amino acids necessary for the construction of body proteins, humans and animals receive as part of food proteins;

3) amino acids are prescribed for severe exhaustion, after heavy operations;

4) they are used to feed patients, bypassing the gastrointestinal tract;

5) amino acids are necessary as a remedy for certain diseases (for example, glutamic acid is used for nervous diseases, histidine for stomach ulcers);

6) some amino acids are used in agriculture for feeding animals, which positively affects their growth;

7) are of technical importance: aminocaproic and aminoenanthic acids form synthetic fibers - nylon and enanth.