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LABORATORY EXPERIMENTS ON THE TOPIC: "GENETIC LINK BETWEEN HYDROCARBONS, ALCOHOLS, ALDEHYDES AND ACIDS"

Limit hydrocarbons

From saturated hydrocarbons methane is studied in detail at the school as a substance that is the simplest in composition and structure, the most accessible for practical acquaintance and of great national economic importance as a chemical raw material and fuel.

Experiments with the first, studied in organic chemistry substance, must be supplied in sufficient quantity and with special methodical care, since they must show new aspects of the experiment in the study of organic chemistry. Here, empirically, it will be possible to establish the composition and molecular formula substances, which is the first step in determining the structural formulas organic compounds.

METHANE.

The order of experiments with methane may be different. Basically, it will be determined by whether the teacher starts the topic with obtaining methane and then sets up experiments to study its properties using the substance obtained in the lesson, or uses pre-prepared methane in order to clearly follow the sequence of studying questions - first consider physical properties substances, then Chemical properties, application of the substance and, finally, obtaining it. AT last case the experience of obtaining methane will be put only at the end of the topic.

The first way of studying the topic and, consequently, constructing an experiment is more methodologically complicated, but more economical in time. The second method will require more time, but it is methodologically simpler and, moreover, valuable in that it will allow in conclusion to repeat and consolidate the knowledge of the basic experiments with the substance when it is received in the lesson.

When studying methane, there is no particular need to set laboratory experiments. In essence, they could be reduced here only to obtaining methane and burning it. But getting methane from sodium acetate and burning it can easily be shown on a demonstration table.

It would be more expedient after studying the entire topic "Hydrocarbons" to deliver a special practical lesson. In this activity, students will replicate the experience of making methane and be able to verify that methane does not decolorize bromine water and potassium permanganate solution.

Obtaining methane in the laboratory. The most convenient laboratory method for producing methane is the interaction of sodium acetate with soda lime.

Salt interaction carboxylic acids with alkali is in a general way obtaining hydrocarbons. Reaction in general view is represented by the equation:

if R = CH 3, then methane is formed.

Since caustic soda is a hygroscopic substance, and the presence of moisture interferes with the successful completion of the reaction, calcium oxide is added to it. Mixture caustic soda with calcium oxide and is called soda lime.

A fairly strong heating is required for the successful course of the reaction, however, excessive overheating of the mixture leads to side processes and the production of undesirable products, such as acetone:

Sodium acetate must be dehydrated prior to testing. Soda lime should also be calcined before preparing the mixture. If there is no ready-made soda lime, it is prepared as follows. In an iron or porcelain cup, well-calcined crushed lime CaO is poured over with half the amount of a saturated aqueous solution of alkali NaOH. The mixture is evaporated to dryness, calcined and crushed. Substances are stored in a desiccator.

To demonstrate the production of methane, it is best to use a small flask with an outlet tube, and for practical session- test tube (Fig. 1 and 2).

Assemble the device as shown in Fig. 1 or 2. An alkali solution is poured into a wash bottle to trap impurities (Fig. I). A mixture of sodium acetate and soda lime is placed in a reaction flask or test tube. To do this, finely divided substances are thoroughly mixed in a volume ratio of 1:3, i.e. with a considerable excess of lime to cause the sodium acetate to react as completely as possible.

Rice.

The flask is heated with a burner through an asbestos mesh, and the test tube on a naked flame. Methane is collected in a test tube according to the method of water displacement. To check the purity of the resulting gas, the test tube is removed from the water and the gas is ignited without turning over.

Since it is not advisable to interrupt the process of obtaining methane, and it is impossible to complete all other experiments while the reaction is in progress, it is recommended to collect gas for subsequent experiments in several cylinders (test tubes) or in a gasometer.

The filled cylinders are left for a while in the bath or they are closed under water with a glass plate (cork) and placed upside down on the table.

Methane is lighter than air. To get acquainted with the physical properties of methane, the teacher demonstrates a cylinder with the collected gas. Students observe that methane is a colorless gas. The collection of methane by the method of displacement of water suggests that this gas is apparently insoluble in water. The teacher confirms this conclusion.

On the scales, two identical flasks of the largest possible capacity are balanced. One of the flasks is suspended upside down (Fig. 3). Methane from the device is passed into this flask for some time. The scales are going up. Lest students think that the change in weight is due to the pressure of the jet of gas on the bottom of the flask, pay attention to the fact that the imbalance remains even after the passage of methane is stopped.

After the scales are again brought into equilibrium (for this, the bottle with methane is turned upside down for a while), for comparison and more convincing conclusions, methane is passed into the flask normally standing on the scales. The balance of the scales is not disturbed.

Having shown that methane is lighter than air, the teacher reports how much it weighs at normal conditions liter of methane. This information will be needed later in the derivation of the molecular formula of the substance.

Combustion of methane. Following a consideration of the physical properties of methane, the question of what is the molecular formula of methane can be raised. The teacher informs that in order to clarify this issue, it will be necessary to first familiarize oneself with one of the chemical properties of methane - combustion.

Combustion of methane can be shown in two ways.

1. A glass cylinder (capacity, for example, 250 ml) filled with methane is placed on the table, a plate is removed from it or the cork is opened and the gas is immediately ignited with a splinter. As the methane burns, the flame descends into the cylinder.

In order for the flame to keep all the time above the cylinder and be clearly visible to students, water can be gradually poured into the cylinder with burning methane, thereby displacing the gas outward (Fig. 4).

2. Methane is ignited directly at the outlet tube of the device for obtaining gas or gasometer (in both cases, a check for purity is obligatory!). The size of the flame is controlled by the heating intensity in the first case and by the height of the displacing liquid column in the second case. If methane is purified from impurities, it burns with an almost colorless flame. To eliminate some of the luminosity of the flame (yellow color) due to the sodium salts in the glass of the tube, a metal tip can be attached to the end of the tube.

ALDEHYDES AND KETONES

When studying aldehydes, students in experiments get acquainted with the stepwise nature of oxidation organic matter, with the chemistry of important production processes and with the principle of obtaining synthetic resins.

In order for students to understand the place of aldehydes in the series of hydrocarbon oxidation products, when compiling chemical equations, one should not avoid using the names and formulas of acids into which aldehydes are converted. The formulas of acids may be given dogmatically in advance; in the future, students will receive experimental justification for them.

In the study of aldehydes, most of the experiments are carried out with formaldehyde as the substance most accessible to the school and of great industrial importance. In accordance with this, formaldehyde is given the main place in this chapter. For acetaldehyde, only production reactions are considered. Ketones are not specifically taught in school; therefore, of these, only one representative is taken here - acetone, and experiments with it are given mainly for extracurricular activities students.

FORMALDEHYDE (METHANAL)

It is advisable to build a plan for studying this substance so that immediately after becoming familiar with the physical properties of aldehydes, students learn how to obtain it, then chemical properties, etc. A slightly earlier acquaintance with the methods of obtaining aldehyde will make it possible further, when studying the chemical properties (oxidation reactions), to consider aldehydes as a link in the hydrocarbon oxidation chain.

Formalin can be used as a sample when getting acquainted with the properties of formaldehyde. This should immediately ensure that students clearly understand the difference between formalin and formaldehyde.

The smell of formaldehyde. Of the physical properties of formaldehyde, familiarization with the smell is the most accessible in practice. For this purpose on student tables test tubes with 0.5-1 ml of formalin are distributed. Once the students are familiar with the smell, the formalin can be collected and used for further experiments. Familiarization with the smell of formalin will enable students to detect this substance in other experiments.

Flammability of formaldehyde. The formalin is heated in a test tube and the vapors released are ignited; they burn with an almost colorless flame. The flame can be seen if you set fire to a splinter or a piece of paper in it. The experiment is carried out in a fume hood.

Obtaining formaldehyde. Since, before getting acquainted with the chemical properties, formaldehyde can only be detected by smell, the first experience of obtaining it should be done in the form of laboratory work.

1. Pour a few drops of methanol into a test tube. In the flame of a burner, a small piece of copper mesh rolled into a tube or a spiral of copper wire is heated and quickly lowered into methanol.

When calcined, copper oxidizes and becomes covered with a black coating of copper oxide, in alcohol it is restored again and turns red:

A strong odor of aldehyde is detected. If the oxidation process is repeated 2-3 times, then a significant concentration of formaldehyde can be obtained and the solution can be used for subsequent experiments.

2. In addition to copper oxide, other oxidizing agents familiar to students can be used to obtain formaldehyde.

To weak solution potassium permanganate in a demonstration tube, add 0.5 ml of methanol and the mixture is heated to boiling. There is a smell of formaldehyde, and purple coloring permanganate disappears.

2-3 ml of a saturated solution of potassium bichromate K 2 Cr 2 O 7 and the same volume of concentrated sulfuric acid are poured into a test tube. Add methanol dropwise and warm the mixture very carefully (point the tube opening to the side!). Further, the reaction proceeds with the release of heat. The yellow color of the chromium mixture disappears and the green color of chromium sulfate appears.

The reaction equation with students can not be disassembled. As in the previous case, they are only informed that potassium dichromate oxidizes methyl alcohol to aldehyde, while turning into a salt of trivalent chromium Cr 2 (SO 4) 3.

The interaction of formaldehyde with silver oxide(reaction of a silver mirror). This experience should be demonstrated to the students in such a way that it simultaneously serves as an instruction for the subsequent practical session.

Obtaining phenol-formaldehyde resins. The bulk of formaldehyde obtained in industry is used for the synthesis of phenol-formaldehyde and other resins necessary for the production of plastics. The production of phenol-formaldehyde resins is based on the polycondensation reaction.

Most available in school conditions synthesis of phenol-formaldehyde resin. By this time, students are already familiar with both starting materials for producing resin - phenol and formaldehyde; the experience is relatively uncomplicated and proceeds smoothly; The chemistry of the process is not particularly difficult for students if it is depicted as follows:

Depending on the quantitative ratio of phenol and formaldehyde, as well as on the catalyst used (acidic or alkaline), novolac or resole resin can be obtained. The first one is thermoplastic and has linear structure above. The second is thermosetting, since its linear molecules contain free alcohol groups - CH 2 OH, capable of reacting with mobile hydrogen atoms of other molecules, resulting in a three-dimensional structure.

ACETEC ALDEHYDE (ETHANAL)

After a detailed acquaintance with the properties of formaldehyde in this section topics of greatest importance are experiments related to the production of acetaldehyde. These experiments can be designed to: a) show that all aldehydes can be obtained by oxidation of the corresponding monohydric alcohols, b) show how the structure of aldehydes can be experimentally substantiated, c) introduce the chemistry of the industrial method for obtaining acetaldehyde according to Kuchsrov.

Preparation of acetaldehyde by oxidation of ethanol. Copper (II) oxide can be taken as an oxidizing agent for alcohol. The reaction proceeds similarly to the oxidation of methanol:

• 1. Not more than 0.5 ml of ethyl alcohol is poured into a test tube and a red-hot copper wire is immersed. The odor of acetaldehyde, reminiscent of fruit, is detected and the reduction of copper is observed. If alcohol is oxidized 2-3 times, each time heating copper until copper oxide is formed, then, having collected the solutions obtained by students in test tubes, it will be possible to use aldehyde for experiments with it.
• 2. Place 5 g of crushed potassium dichromate K2Cr2O7 into a small flask with a drain tube, pour 20 ml of dilute sulfuric acid (1:5) and then 4 ml of ethyl alcohol. A refrigerator is attached to the flask and heated on a small flame through an asbestos mesh. The receiver for the distillate is placed in ice water or snow. A little water is poured into the receiver and the end of the refrigerator is lowered into the water. This is done in order to reduce the volatilization of acetaldehyde vapors (bp 21 °C). Together with ethanol, a certain amount of water, unreacted alcohol, formed acetic acid and other by-products reactions. However, there is no need to isolate pure acetaldehyde, since the resulting product gives good common reactions aldehydes. The presence of aldehyde is determined by smell and by the reaction of a silver mirror.

Students' attention is drawn to the color change in the flask. The green color of the resulting chromium sulfate (III) Cr 2 (SO 4) 3 becomes especially distinct if the contents of the flask are diluted with water after the experiment. It is noted that the change in the color of potassium bichromate occurred due to the oxidation of alcohol by it.

Obtaining acetaldehyde by hydration of acetylene. The remarkable discovery of the Russian chemist M.G. Kucherov - the addition of water to acetylene in the presence of mercury salts formed the basis of a widespread industrial method for producing acetaldehyde.

In spite of great importance and accessibility for the school, this method is rarely demonstrated in chemistry classes.

In industry, the process is carried out by passing acetylene into water containing divalent mercury salts and sulfuric acid at a temperature of 70°C. The acetaldehyde formed under these conditions is distilled off and condensed, after which it enters special towers for oxidation into acetic acid. Acetylene is obtained from calcium carbide in the usual way and purified from impurities.

The need to purify acetylene and maintain the temperature in the reaction vessel, on the one hand, and the uncertainty in obtaining the desired product, on the other, usually reduce interest in this experiment. Meanwhile, the experiment can be carried out quite simply and reliably both in a simplified form and under conditions approaching industrial ones.

1. An experiment that, to a certain extent, reflects the conditions for carrying out the reaction in production and makes it possible to obtain a sufficiently concentrated solution of aldehyde, can be carried out in the device shown in fig. 29.

The first stage is the production of acetylene. Pieces of calcium carbide are placed in the flask and water or a saturated solution of common salt is slowly added from the dropping funnel. The pinning speed is adjusted so that a steady flow of acetylene is established, approximately one bubble per 1-2 s. Purification of acetylene is carried out in a washer with a solution of copper sulfate:

CuSO 4 + H 2 S H 2 SO 4

After purification, the gas is passed into a flask with a catalyst solution (15–20 ml of water, 6–7 ml of conc. sulfuric acid and about 0.5 g of mercury (II) oxide. The flask, where acetylene is hydrated, is heated with a burner (alcohol) , and the resulting acetaldehyde in gaseous form enters test tubes with water, where it is absorbed.

After 5--7 minutes in a test tube, it is possible to obtain a solution of ethanal of a significant concentration. To complete the experiment, first stop the water supply to the calcium carbide, then disconnect the device and, without any additional distillation of the aldehyde from the reaction flask, use the resulting solutions in test tubes for the corresponding experiments.

2. In the most simplified form, the reaction of M.G. Kucherov can be carried out as follows.

In a small round-bottom flask, 30 ml of water and 15 ml of conc. sulfuric acid. The mixture is cooled and a little (on the tip of a spatula) mercury oxide (II) is added to it. The mixture is heated carefully through an asbestos mesh to a boil, while mercury oxide is converted into mercury (II) sulfate.

The theme of the lesson " genetic connection hydrocarbons, alcohols, aldehydes and ketones” Purpose To develop the skills of drawing up structural formulas for this information. To form the skill of implementing chains of transformations of organic substances. Improve knowledge of the classification and nomenclature of organic substances.

The program of activities "Compilation of the structural formula of a substance from this information" 1) Translate this information into the language of diagrams. 2) Assume the connection class. 3) Set the compound class and its structural formula. 4) Write the equations of the ongoing reactions.

Program of activities: "Implementation of chains of transformations" 1). number chemical reactions. 2). Determine and sign the class of each substance in the chain of transformations. 3). Analyze the chain: A) Above the arrow, write the formulas of the reagents and the reaction conditions; B) Under the arrow, write the formulas for additional products with a minus sign. 4). Write the reaction equations: A) Arrange the coefficients; b) Name the products of the reaction.

Classification of organic compounds according to the structure of the carbon chain 1. Depending on the nature of the carbon skeleton, acyclic (linear and branched and cyclic compounds) are distinguished. Acyclic (aliphatic, non-cyclic) compounds - compounds that have an open linear or branched UC are often called normal. containing molecules closed in a cycle of UC

Classification of individual carbon atoms In the carbon skeletons themselves, it is customary to classify individual carbon atoms according to the number of chemically bonded carbon atoms. If a given carbon atom is bonded to one carbon atom, then it is called primary, with two - secondary, three - tertiary and four - Quaternary. In the carbon skeletons themselves, it is customary to classify individual carbon atoms by the number of chemically bonded carbon atoms. If a given carbon atom is bonded to one carbon atom, then it is called primary, with two - secondary, three - tertiary and four - Quaternary. What is the name of the carbon atom depicted: What is the name of the carbon atom depicted: a) inside the circle _________________; b) inside the square __________________; c) inside the heart __________________; d) inside the triangle _________________;

15) hydrogen bond between molecules.
Physical properties of alcohols.
1. The strength of a hydrogen bond is much less than the strength of a conventional covalent bond (about 10 times).
2. At the expense hydrogen bonds alcohol molecules turn out to be associated, as if stuck to each other, it is necessary to expend additional energy to break these bonds so that the molecules become free and the substance acquires volatility.
3. This is the reason for the higher boiling point of all alcohols compared to the corresponding hydrocarbons.
4. Water at such a low molecular weight has an unusually high boiling point.

40. Chemical properties and application of saturated monohydric alcohols

As substances containing carbon and hydrogen, alcohols burn when ignited, releasing heat, for example:
С2Н5ОН + 3O2? 2CO2 + 3H2O +1374 kJ,
When burning, they also have differences.
Experience Features:
1) it is necessary to pour 1 ml of various alcohols into porcelain cups and set fire to the liquid;
2) it will be noticeable that alcohols - the first representatives of the series - ignite easily and burn with a bluish, almost non-luminous flame.
Features of these phenomena:
a) from the properties due to the presence of the OH functional group, it is known about the interaction of ethyl alcohol with sodium: 2C2H5OH + 2Na? 2C2H5ONa + H2;
b) the product of substitution of hydrogen in ethanol is called sodium ethoxide, it can be isolated after the reaction in solid form;
c) react with alkali metals other soluble alcohols which form the corresponding alcoholates;
d) the interaction of alcohols with metals comes with ionic splitting of the polar O-H bond;
e) in such reactions, alcohols exhibit acidic properties - the elimination of hydrogen in the form of a proton.
The decrease in the degree of dissociation of alcohols compared to water can be explained by the influence of the hydrocarbon radical:
a) the shift by the radical of the electron density of the C-O bond towards the oxygen atom leads to an increase in the last partial negative charge, while it holds the hydrogen atom more firmly;
b) the degree of dissociation of alcohols can be increased if a substituent is introduced into the molecule, which attracts the electrons of the chemical bond.
This can be explained as follows.
1. The chlorine atom shifts the electron density of the Cl-C bond towards itself.
2. A carbon atom, acquiring a partial positive charge, to compensate for it, shifts the electron density in its direction C-C connections.
3. For the same reason, the electron density of the C-O bond shifts somewhat towards the carbon atom, and the density of the O-H bond shifts from the hydrogen atom to oxygen.
4. The possibility of splitting off hydrogen in the form of a proton from this increases, while the degree of dissociation of the substance increases.
5. In alcohols, not only the hydroxyl hydrogen atom, but the entire hydroxyl group can enter into chemical reactions.
6. If you heat ethyl alcohol with hydrohalic acid, for example, hydrobromic acid, in a flask with a refrigerator attached to it (a mixture of potassium bromide or sodium bromide with sulfuric acid is taken to form hydrogen bromide), then after a while you can notice that heavy water is collected in the receiver under a layer of water. liquid - bromoethane.

41. Methanol and ethanol

Methyl alcohol, or methanol, its features:
1) structural formula - CH3OH;
2) it is a colorless liquid with a boiling point of 64.5 °C;
3) poisonous (may cause blindness, death);
4) in large quantities, methyl alcohol is obtained by synthesis from carbon monoxide (II) and hydrogen at high pressure(20–30 MPa) and high temperature(400 °C) in the presence of a catalyst (about 90% ZnO and 10% Cr2O3): CO + 2H2? CH3OH;
5) methyl alcohol is also formed during the dry distillation of wood, therefore it is also called wood alcohol. It is used as a solvent, as well as to obtain other organic substances.
Ethyl (wine) alcohol, or ethanol, its features:
1) structural formula - CH3CH2OH;
2) boiling point 78.4 °C;
3) ethanol is one of the most important starting materials in the modern organic synthesis industry.
Methods for obtaining ethanol:
1) various sugary substances are used to obtain (grape sugar, glucose, which turns into ethyl alcohol by "fermentation"). The reaction proceeds according to the scheme:
C6H12O6(glucose) ? 2C2H5OH + 2CO2.
2) free glucose is found, for example, in grape juice, the fermentation of which produces grape wine with an alcohol content of 8 to 16%;
3) the initial product for obtaining alcohol can be starch polysaccharide, which is contained, for example, in potato tubers, grains of rye, wheat, corn;
4) for conversion into sugary substances (glucose), starch is preliminarily subjected to hydrolysis.
To do this, flour or chopped potatoes are brewed with hot water and, when cooled, malt is added to it.
Malt- these are barley grains germinated, and then dried and pounded with water.
Malt contains diastase, which acts catalytically on the process of starch saccharification.
diastasis is a complex mixture of enzymes;
5) at the end of saccharification, yeast is added to the resulting liquid, under the action of enzymes of which (zymase) alcohol is formed;
6) it is distilled off and then purified by repeated distillation.
Currently, the polysaccharide, cellulose (fiber), which forms the main mass of wood, is also subjected to saccharification.
To do this, cellulose undergoes hydrolysis in the presence of acids (for example, sawdust at 150–170 ° C is treated with 0.1–5% sulfuric acid at a pressure of 0.7–1.5 MPa).

42. Alcohols as derivatives of hydrocarbons. Industrial synthesis of methanol

Genetic link between alcohols and hydrocarbons:
1) alcohols can be considered as hydroxyl derivatives of hydrocarbons;
2) they can also be attributed to partially oxidized hydrocarbons, since, in addition to carbon and hydrogen, they also contain oxygen;
3) it is quite difficult to directly replace a hydrogen atom with a hydroxyl group or introduce an oxygen atom into a hydrocarbon molecule;
4) this can be done through halogen derivatives.
For example, to get ethyl alcohol from ethane, you first need to get bromoethane:
C2H6 + Br? C2H5Br + HBr.
And then turn bromoethane into alcohol by heating with aqueous alkali:
C2H5 Br + H OH? C2H5OH + HBr;
5) alkali is needed to neutralize hydrogen bromide and eliminate the possibility of its reaction with alcohol;
6) in the same way, methyl alcohol can be obtained from methane: CH4? CH3Br ? CH3OH;
7) alcohols are genetically related to unsaturated hydrocarbons.
For example, ethanol is obtained by hydration of ethylene:
CH2=CH2? H2O=CH3-CH2-OH.
The reaction proceeds at a temperature of 280–300 °C and a pressure of 7–8 MPa in the presence of phosphoric acid as a catalyst.
Industrial synthesis of methanol, its features.
1. Methyl alcohol cannot be obtained by hydration unsaturated hydrocarbon.
2. It is obtained from synthesis gas, which is a mixture of carbon monoxide (II) with hydrogen.
Methyl alcohol from synthesis gas is obtained by the reaction:
CO + 2H2? CH3OH + Q.
Characteristic features of the reaction.
1. The reaction goes in the direction of reducing the volume of the mixture, while the shift of equilibrium towards the formation of the desired product will be facilitated by an increase in pressure.
2. In order for the reaction to proceed at a sufficient rate, a catalyst and an elevated temperature are needed.
3. The reaction is reversible, the initial substances do not completely react when passing through the reactor.
4. In order to use them economically, the alcohol that is formed must be separated from the reaction products, and the unreacted gases must be sent back to the reactor, i.e., to carry out a circulation process.
5. In order to save energy costs, the waste products of the exothermic reaction must be used to heat the gases that are used for synthesis.

43. The concept of pesticides

Pesticides (pesticides)- This chemicals control of microorganisms that are harmful or undesirable from an economic or public health point of view.
The most important types of pesticides are as follows.
1. Herbicides. Basic properties:
a) these are weed control preparations, which are divided into arboricides and algicides;
b) these are phenoxy acids, derivatives of benzoic acid;
c) these are dinitroanilines, dinitrophenols, halophenols;
d) these are many heterocyclic compounds;
e) the first synthetic organic herbicide - 2-methyl-4,6-dinitrophenol;
f) other commonly used herbicides - atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine); 2,4-dichlorophenoxyacetic acid.
2. Insecticides. Peculiarities:
a) these are substances that destroy harmful insects, they are usually divided into anti-feeding agents, attractans and chemosterilizers;
b) these include organochlorine, organophosphorus substances, preparations that contain arsenic, sulfur preparations, etc.;
c) one of the most famous insecticides - dichlorodiphenyl-trichloromethylmethane (DDT);
d) are widely used in agriculture and household insecticides such as hexachloran (hexachlorocyclohexane).
3. Fungicides.
Characteristic features of fungicides:
a) these are substances for combating fungal diseases of plants;
b) various antibiotics, sulfanilamide preparations are used as fungicides;
c) one of the simplest fungicides in terms of chemical structure is pentachlorophenol;
d) most pesticides have toxic properties not only against pests and pathogens;
e) if mishandled, they can cause poisoning of people, domestic and wild animals or the death of cultural crops and plantings;
f) pesticides must be used very carefully, strictly following the instructions for their use;
g) in order to minimize the harmful effects of pesticides on the environment, the following should be done:
- apply substances with higher biological activity and, accordingly, apply them in a smaller amount per unit area;
- apply substances that are not stored in the soil, but decompose into harmless compounds.

44. Polyhydric alcohols

Structural features of polyhydric alcohols:
1) contain in the molecule several hydroxyl groups connected to a hydrocarbon radical;
2) if two hydrogen atoms are replaced by hydroxyl groups in a hydrocarbon molecule, then this is a dihydric alcohol;
3) the simplest representative of such alcohols is ethylene glycol (ethanediol-1,2):
CH2(OH) - CH2(OH);
4) in all polyhydric alcohols, hydroxyl groups are located at different carbon atoms;
5) to obtain an alcohol in which at least two hydroxyl groups would be at one carbon atom, many experiments were carried out, but the alcohol could not be obtained: such a compound turns out to be unstable.
Physical properties of polyhydric alcohols:
1) key representatives polyhydric alcohols are ethylene glycol and glycerin;
2) these are colorless syrupy liquids with a sweetish taste;
3) they are highly soluble in water;
4) these properties are also inherent in other polyhydric alcohols, for example, ethylene glycol is poisonous.
Chemical properties of polyhydric alcohols.
1. As substances that contain hydroxyl groups, polyhydric alcohols have similar properties to monohydric alcohols.
2. Under the action of hydrohalic acids on alcohols, the hydroxyl group is replaced:
CH2OH-CH2OH + H CI ? CH2OH-CH2CI + H2O.
3. Many alcohols have and special properties: polyhydric alcohols exhibit more acidic properties than monoatomic ones and easily form alcoholates not only with metals, but also with hydroxides of heavy metals. Unlike monohydric alcohols, polyhydric alcohols react with copper hydroxide, giving complexes of blue color (qualitative reaction for polyhydric alcohols).

4. Using the example of polyhydric alcohols, one can verify that quantitative changes pass into qualitative changes: the accumulation of hydroxyl groups in the molecule caused, as a result of their mutual appearance, new properties in alcohols compared to monohydric alcohols.
Methods for the preparation and use of polyhydric alcohols: 1) like monohydric alcohols, polyhydric alcohols can be obtained from the corresponding hydrocarbons through their halogen derivatives; 2) the most common polyhydric alcohol is glycerol, it is obtained by splitting fats, and now more and more synthetically from propylene, which is formed during the cracking of petroleum products.

45. Phenols

Hydroxyl derivatives that contain functional groups in side chain, belong to the class of alcohols.
Phenols - are hydroxyl derivatives aromatic hydrocarbons, in the molecules of which the functional groups are linked to the benzene ring.
The simplest phenol is the monoatomic hydroxyl derivative of benzene C6H5OH, which is usually called phenol.
Phenol properties:
1) it is a crystalline colorless substance with a characteristic odor, with partial oxidation in air it is often pink in color, very fusible;
2) phenol has some similarity in chemical properties with monohydric alcohols;
3) if phenol is slightly heated (until melting) and metallic sodium is placed in it, then hydrogen is released. In this case, by analogy with alcoholates, sodium phenolate 2C6H5OH + 2Na? 2C6H5ONa + H2;
4) unlike alcoholates, phenolate is obtained if phenol is treated with an alkali solution;
5) at the same time, solid phenol turns into sodium phenolate, which quickly dissolves in water: C6H5OH + NaOH? C6H5ONa + H2O;
6) taking into account the ionic bond splitting, the equation becomes next view: С6Н5О(Н) + Na++ OH-? [C6H5O]-+ Na++ H2O.
Reaction feature:
a) in these reactions, the acidic properties of phenol are manifested;
b) the degree of dissociation of phenol is greater than that of water and saturated alcohols, therefore it is also called carbolic acid;
3) Phenol is a weak acid, even carbonic acid is stronger, it can displace phenol from sodium phenolate.
Methods for the use and production of phenol
1. As a substance that kills many microorganisms, phenol has long been used as an aqueous solution to disinfect rooms, furniture, surgical instruments, etc.
2. He goes to obtain dyes, many medicinal substances.
3. A particularly large amount of it is spent on the production of widespread phenol-formaldehyde plastics.
4. For industrial needs, phenol is primarily used, which is obtained from coal tar.
But this source cannot fully satisfy the need for phenol.
Therefore, in large quantities, it is also produced synthetically from benzene.
Aldehydes- These are organic substances whose molecules contain a functional group of atoms connected to a hydrocarbon radical.

46. ​​Aldehydes and their chemical properties

Aldehydes- These are organic substances whose molecules contain a carbonyl group, which is associated with at least one hydrogen atom and a hydrocarbon radical.

The chemical properties of aldehydes are determined by the presence of a carbonyl group in their molecule. At the place of the double bond in the molecule of the carbonyl group, addition reactions can take place. If, for example, formaldehyde vapors are passed together with hydrogen over a heated nickel catalyst, hydrogen is added: formaldehyde is reduced to methyl alcohol. The polar nature of the double bond also determines other reactions of aldehydes, such as the addition of water.
Features of the water addition reaction: a) to the carbon atom of the carbonyl group, which carries a partial positive charge, due to electron pair the oxygen atom is joined by a hydroxyl group; b) an electron pair?-bond passes to the oxygen atom of the carbonyl group and a proton is added to the oxygen;
The addition reaction is characterized by:
1) hydrogenation (reduction) with the formation of primary alcohols RCH2OH.
2) addition of alcohols to form hemiacetals R-CH (OH) - OR.
In the presence of a catalyst, hydrogen chloride HCl, and with an excess of alcohol, acetals RCH (OR) 2 are formed;
3) addition of sodium hydrosulfite NaHSO3 to form hydrosulfite derivatives of aldehydes.
Features of the oxidation reaction of aldehydes: interact with an ammonia solution of silver (I) oxide and with copper (II) hydroxide to form carboxylic acids.
Features of the polymerization reaction of aldehydes: 1) linear polymerization is characteristic; 2) cyclic polymerization is characteristic (trimerization, tetramerization).
Features of the "silver mirror" reaction: 1) silver appears on the walls of the test tube in the form of a shiny coating; 2) in such a redox reaction, the aldehyde is converted into an acid (with an excess of ammonia, an ammonium salt is formed); 3) silver is released in free form; 4) copper hydroxide Сu(OH)2 can also be used as an oxidizing agent for aldehydes; 3) if an aldehyde solution is added to copper hydroxide and the mixture is heated, a yellow precipitate of copper (I) hydroxide is formed, which turns into red copper oxide; 4) copper (II) hydroxide oxidizes the aldehyde into an acid, and itself is reduced to copper (I) oxide.
Reactions with an ammonia solution of silver(I) oxide and copper(II) hydroxide can serve to detect aldehydes.
Carbonyl compounds can be reduced to alcohols. Aldehydes are reduced to primary alcohols, and ketones to secondary alcohols. Some methods allow you to reduce the carbonyl group to methylene.

47. Application and production of aldehydes

The use of aldehydes.
Of the aldehydes, formaldehyde is the most widely used. Features of the use of formaldehyde: it is usually used in the form of an aqueous solution - formalin; many uses of formaldehyde are based on the ability to fold proteins; in agriculture, formalin is necessary for dressing seeds; formalin is used in leather production; formalin has a tanning effect on skin proteins, makes them harder, non-rotting; formalin is also used to preserve biological preparations; when formaldehyde reacts with ammonia, the well-known medicinal substance urotropin is obtained.
The bulk of formaldehyde is used to obtain phenol-formaldehyde plastics, which are used to make: a) electrical products; b) machine parts, etc. Acetaldehyde (acetic aldehyde) is used in large quantities for the production of acetic acid.
Ethyl alcohol is obtained by reduction of acetaldehyde in some countries.
Obtaining aldehydes:
1) the general method for obtaining aldehydes is the oxidation of alcohols;
2) if you heat a spiral of copper wire in the flame of an alcohol lamp and lower it into a test tube with alcohol, then the wire, which is covered with a dark coating of copper (II) oxide when heated, becomes shiny in alcohol;
3) the smell of aldehyde is also detected.
With the help of such a reaction, formaldehyde is obtained in industry.
To obtain formaldehyde, a mixture of methyl alcohol vapors with air is passed through a reactor with a red-hot grid of copper or silver;
4) in the laboratory preparation of aldehydes, other oxidizing agents can be used for the oxidation of alcohols, for example, potassium permanganate;
5) in the formation of aldehyde, alcohol, or alcohol, undergoes dehydrogenation.
Features of the acetylene hydration reaction:
a) first, water is added to acetylene at the site of one?-bond;
b) vinyl alcohol is formed;
c) unsaturated alcohols, in which the hydroxyl group is located at the carbon atom, which is linked by a double bond, are unstable and easily isomerized;
d) vinyl alcohol is converted to aldehyde:

E) the reaction is easily carried out if acetylene is passed into heated water, which contains sulfuric acid and mercury (II) oxide;
f) after a few minutes, an aldehyde solution can be detected in the receiver.
In recent years, a method has been developed and is gaining distribution for the production of acetaldehyde by the oxidation of ethylene with oxygen in the presence of palladium and copper chlorides.

48. Formaldehyde and acetaldehyde

The structure and properties of formaldehyde: it is a colorless gas with a pungent, suffocating odor, poisonous; it is highly soluble in water; an aqueous 40% solution of formaldehyde is called formalin.
Chemical properties of formaldehyde.
Formaldehyde is characterized by oxidation and addition reactions (including polycondensation):
1) oxidation reaction:
a) the oxidation reaction proceeds very easily - aldehydes are able to take oxygen from many compounds;
b) when formaldehyde is heated with an ammonia solution of silver oxide (silver oxide is insoluble in water), formaldehyde is oxidized to formic acid HCOOH and silver is reduced. Education "silver mirror" serves as a qualitative reaction to the aldehyde group;
d) aldehydes reduce copper (II) hydroxide to copper (I) hydroxide, which turns into orange copper (I) oxide;
e) the reaction proceeds when heated: 2CuOH? Cu2O + H2O;
f) this reaction can also be used to detect aldehydes;
2) addition reaction:
a) the addition reaction proceeds by breaking the double bond of the carbonyl group of the aldehyde;
b) the addition of hydrogen, which occurs when a mixture of formaldehyde and hydrogen is passed over a heated catalyst - nickel powder, leads to the reduction of aldehyde to alcohol;
c) formaldehyde also attaches ammonia, sodium hydrosulfite and other compounds.
Methods for obtaining formaldehyde:
1) in industry, formaldehyde is obtained from methanol by passing alcohol vapor together with air over a copper catalyst heated to 300 ° C: 2CH3OH + O2 ? 2HCHO + 2H2O;
2) an important industrial method is also the oxidation of methane with air at 400–600°C in the presence of a small amount of nitric oxide as a catalyst: CH4 + O2 ? CH2O + H2O.
Application of formaldehyde: 1) formaldehyde is used in large quantities for the production of phenol-formaldehyde resins; 2) it serves as a starting material for the production of dyes, synthetic rubber, medicinal substances, explosives and etc.
Features of acetaldehyde: acetaldehyde (or acetaldehyde, or ethanal) is a colorless liquid with a pungent odor, highly soluble in water; the addition of hydrogen to acetaldehyde proceeds under the same conditions as to formaldehyde.
Features of paraldehyde: it is a liquid that solidifies into a crystalline mass at 12 ° C, and when heated in the presence of dilute mineral acids, it turns into acetaldehyde; has a strong hypnotic effect.

49. Polycondensation reaction. Carbohydrates

polycondensation- this is the process of formation of high-molecular compounds from low-molecular ones, which is accompanied by the release of a by-product (water, ammonia, hydrogen chloride and other substances).
Features of the polycondensation reaction:
1) during polymerization, in contrast to polycondensation, the release of side substances does not occur;
2) polycondensation products (excluding by-products), as well as polymerization products, are called polymers;
3) during the polycondensation reaction, the chain grows gradually: first, the initial monomers interact with each other, then the formed compounds alternately react with the molecules of the same monomers, eventually forming a polymer compound. An example of a polycondensation reaction is the formation of phenol-formaldehyde resins, which are used for the manufacture of plastics;
4) the reaction proceeds when heated in the presence of a catalyst (acid or alkali);
5) in the phenol molecule, hydrogen atoms are mobile, and the carbonyl group of aldehyde is capable of addition reactions, while phenol and formaldehyde interact with each other;
6) the resulting compound interacts further with phenol with the release of a water molecule;
7) the new compound interacts with formaldehyde;
8) this compound condenses with phenol, then again with formaldehyde, etc.;

Tazhibaeva Asemgul Isintaevna

Teacher of Kamennobrodskaya high school

Chemistry lesson in grade 11

Lesson topic: Genetic relationship between hydrocarbons, alcohols, aldehydes, alcohols, carboxylic acids.

Lesson type: lesson generalization of knowledge.

Lesson Objectives: consolidate, generalize and systematize knowledge on oxygen-containing organic compounds, including on the basis of the genetic relationship between the classes of these substances. To consolidate the ability to predict the chemical properties of unfamiliar organic substances, based on knowledge functional groups. To develop in students evidence-based speech, the ability to use chemical terminology, conduct, observe and describe chemical experiment. Raise the need for knowledge about those substances with which we come into contact in life.

Methods: verbal, visual, practical, problem-search, knowledge control.

Reagents: acetylsalicylic acid(aspirin), water, iron(III) chloride, glucose solution, universal indicator, copper(II) sulfate solution, sodium hydroxide solution, egg white, ethanol, butanol-1, acetic acid, stearic acid.

Equipment: computer, screen, projector, table "Classification of oxygen-containing organic substances", reference abstract“A functional group determines the properties of a substance”, a mortar and pestle, a glass rod, a spirit lamp, a test tube holder, a funnel, a filter, glasses, a stand with test tubes, a pipette, a 10 ml measuring cylinder.

I. Organizational moment.

Today in class:

1) You will consolidate the ability to predict the chemical properties of unfamiliar organic substances, based on knowledge of functional groups.

2) You will find out what functional groups you know are part of the most famous antipyretic.

3) You will find functional groups in a sweet-tasting substance that is used in medicine as a nutrient and a component of blood-substituting fluids.

4) You will see how you can get pure silver.

5) We will talk about the physiological effects of ethyl alcohol.

6) We will discuss the consequences of alcohol consumption by pregnant women.

7) You will be pleasantly surprised: it turns out that you already know so much!

II. Repetition and generalization of the acquired knowledge of students.

1. Classification of oxygen-containing organic compounds.

Generalization of the material begins with the classification of oxygen-containing organic substances. To do this, we will use the table "Classification of oxygen-containing organic compounds." In the course of frontal work, we will repeat the oxygen-containing functional groups.

In organic chemistry, there are three major functional groups that include oxygen atoms:hydroxyl, carbonyl andcarboxyl. The latter can be seen as a combination of the two previous ones. Depending on which atoms or groups of atoms these functional groups are associated with, oxygen-containing substances are divided into alcohols, phenols, aldehydes, ketones and carboxylic acids.

Consider these functional groups and their influence on the physical and chemical properties of substances.

Viewing a video clip.

You already know that this is not the only possible classification feature. There can be several identical functional groups in a molecule, and pay attention to the corresponding line of the table.

The next line reflects the classification of substances according to the type of radical associated with the functional group. I would like to draw attention to the fact that, unlike alcohols, aldehydes, ketones and carboxylic acids, hydroxyarenes are distinguished into a separate class of compounds - phenols.

The number of functional groups and the structure of the radical determine the general molecular formula of substances. In this table, they are given only for the limiting representatives of classes with one functional group.

All classes of compounds that "fit" in the table aremonofunctional, i.e., they carry only one oxygen-containing function.

To consolidate the material on the classification and nomenclature of oxygen-containing substances, I give several formulas of compounds and ask students to determine “their place” in the above classification and give a name.

formula

The relationship between the structure and properties of oxygen-containing compounds.

The nature of the functional group has a significant impact on the physical properties of substances of this class and largely determines its chemical properties.

The concept of "physical properties" includes the aggregate state of substances.

State of aggregation line connections different classes:

Number of atoms C in a molecule

The homologous series of aldehydes begins with a gaseous substance at room temperature - formaldehyde, and there are no gases among monohydric alcohols and carboxylic acids. What is it connected with?

Molecules of alcohols and acids are additionally linked to each other by hydrogen bonds.

The teacher asks students to formulate the definition of "hydrogen bond" (this is an intermolecular bond between the oxygen of one molecule and the hydroxyl hydrogen of another molecule), corrects it and, if necessary, dictates for recording: chemical bond between an electron-deficient hydrogen atom and an electron-rich atom of an element with high electronegativity (F , O , N ) is calledhydrogen.

Now compare the boiling points (°C) of the first five homologues of substances of three classes.

Number of atoms C in a molecule

What can be said after looking at the tables?

In the homologous series of alcohols and carboxylic acids, there are no gaseous substances and boiling points are high. This is due to the presence of hydrogen bonds between molecules. Due to hydrogen bonds, the molecules are associated (as if cross-linked), therefore, in order for the molecules to become free and acquire volatility, it is necessary to expend additional energy to break these bonds.

What can be said about the solubility of alcohols, aldehydes and carboxylic acids in water? (Demonstration of the solubility of alcohols in water - ethyl, propyl, butyl and acids - formic, acetic, propionic, butyric and stearic. A solution of formic aldehyde in water is also demonstrated.)

When answering, a scheme is used for the formation of hydrogen bonds between the molecules of acid and water, alcohols, acids.

It should be noted that with increasing molecular weight, the solubility of alcohols and acids in water decreases. The larger the hydrocarbon radical in an alcohol or acid molecule, the more difficult it is for the OH group to keep the molecule in solution due to the formation of weak hydrogen bonds.

3. Genetic relationship between different classes of oxygen-containing compounds.

I draw on the board the formulas of a number of compounds containing one carbon atom each:

CH 4 → CH 3 OH → HCOH → HCOOH → CO 2

Why are they studied in this order in the course of organic chemistry?

How does the oxidation state of a carbon atom change?

Students dictate a line: -4, -2, 0, +2, +4

Now it becomes clear that each subsequent compound is an increasingly oxidized form of the previous one. From this it is obvious that to move along genetic series from left to right followed by oxidation reactions, and in reverse direction– using recovery processes.

Do ketones fall out of this "circle of relatives"? Of course not. Their precursors are secondary alcohols.

The chemical properties of each class of substances were discussed in detail in the corresponding lessons. To summarize this material, I offered as homework assignments on interchanges in a somewhat unusual form.

1. Compound with molecular formulaC 3 H 8 O subjected to dehydrogenation, resulting in a product of the compositionC 3 H 6 O . This substance undergoes a "silver mirror" reaction, forming a compoundC 3 H 6 O 2 . The action of the latter substance with calcium hydroxide gave a substance used as a food additive under the code E 282. It inhibits the growth of mold in bakery and confectionery products and, in addition, is found in products such as Swiss cheese. Determine the formula of the additive E 282, write the equations of the mentioned reactions and name all organic substances.

Decision :

CH 3 – CH 2 – CH 2 –OH→CH 3 – CH 2 – COH+H 2 ( cat. – Cu, 200-300 °C)

CH 3 – CH 2 – COH + Ag 2 O→CH 3 – CH 2 – COOH + 2Ag (simplified form of the equation, ammonia solution of silver oxide)

2CH 3 – CH 2 – COOH+Witha(OH) 2 → (CH 3 – CH 2 – COO) 2 Ca+2H 2 Oh

Answer: calcium propionate.

2. Composition connectionC 4 H 8 Cl 2 with unbranched carbon skeleton heated with an aqueous solutionNaOH and received organic matter, which, when oxidizedCu(OH) 2 turned intoC 4 H 8 O 2 . Determine the structure of the original compound.

Decision: if 2 chlorine atoms are on different carbon atoms, then when treated with alkali, we would get a dihydric alcohol that would not oxidizeCu(OH) 2 . If 2 chlorine atoms were at one carbon atom in the middle of the chain, then when treated with alkali, a ketone would be obtained that does not oxidizeCu(OH) 2. Then the desired connection is1,1-dichlorobutane.

CH 3 – CH 2 – CH 2 – CHCl 2 + 2NaOH → CH 3 – CH 2 – CH 2 – COH + 2NaCl + H 2 O

CH 3 – CH 2 – CH 2 – COH + 2Cu(OH) 2 → CH 3 – CH 2 – CH 2 – COOH + Cu 2 O+2H 2 O

3. When 19.2 g of sodium salt of saturated monobasic acid was heated with sodium hydroxide, 21.2 g of sodium carbonate was formed. Name the acid.

Decision:

When heated, decarboxylation occurs:

R-COONa + NaOH → RH + Na 2 CO 3

υ (Na 2 CO 3 ) = 21,2 / 106 = 0,2 mole

υ (R-COONa) = 0.2 mole

M(R-COONa) = 19.2 / 0.2 = 96 G/ mole

M(R-COOH) = M(R-COONa) -M(Na) + M(H) = 96-23+1= 74G/ mole

In accordance with general formula limiting monobasic carboxylic acids to determine the number of carbon atoms, it is necessary to solve the equation:

12n + 2n + 32= 74

n=3

Answer: propionic acid.

To consolidate knowledge about the chemical properties of oxygen-containing organic substances, let's perform a test.

1 option

Limiting monohydric alcohols correspond to the formulas:
BUT) CH 2 O
B) C 4 H 10 O
AT) C 2 H 6 O
G) CH 4 O
D) C 2 H 4 O 2

It is a combination of two principles,
One is in the birth of mirrors.
Certainly not for contemplation
And for the science of understanding.
... And in the kingdom of the forest she meets,
The little brothers are her friends here,
Their hearts are full...

options:
A) picric acid
B) formic acid
B) acetic acid
D) carboxyl group
D) benzoic acid

Ethanol reacts with substances:
BUT) NaOH
B) Na
AT) HCl
G) CH 3 COOH
D) FeCl 3

A qualitative reaction to phenols is a reaction with
BUT) NaOH
B) Cu(OH) 2
AT) CuO
G) FeCl 3
D) HNO 3

Ethanal reacts with substances
A) methanol
B) hydrogen
C) ammonia solution of silver oxide
D) copper (II) hydroxide
D) hydrogen chloride

Option 2

Aldehydes can be obtained
A) oxidation of alkenes
B) oxidation of alcohols
C) hydration of alkynes
D) when heating calcium salts of carboxylic acids
D) hydration of alkenes

The functional group of alcohols is
BUT) COH
B) Oh
AT) COOH
G) NH 2
D) NO 2

2-methylbutanol-2
A) unsaturated alcohol
B) saturated alcohol
B) monohydric alcohol
D) tertiary alcohol
D) aldehyde

Did you see the reaction
A) polyhydric alcohols
B) alcohol oxidation
C) the interaction of phenol with iron (III) chloride
D) "silver mirror"
D) "copper mirror"

Acetic acid reacts with substances
A) hydrogen
B) chlorine
B) propanol
D) sodium hydroxide
D) metanalem

Students write their answers in the table:

1, 2 var.

If you connect the correct answers with a solid line, you get the number "5".

Group work of students.

Task for 1 group

Goals:

Reagents and equipment: acetylsalicylic acid (aspirin), water, iron(III) chloride; mortar and pestle, glass rod, spirit lamp, test tube holder, funnel, filter, glasses, test tube stand, pipette, 10 ml measuring cylinder.

Experience 1. Proof of the absence of phenolic hydroxyl in acetylsalicylic acid (aspirin).

Place 2-3 grains of acetylsalicylic acid in a test tube, add 1 ml of water and shake vigorously. 1-2 drops of iron(III) chloride solution are added to the resulting solution. What are you watching? Draw your own conclusions.

Violet coloration does not appear. Therefore, in acetylsalicylic acidNOOS-S 6 H 4 -O-CO-CH 3 there is no free phenolic group, since this substance is ester formed by acetic and salicylic acids.

Experience 2. Hydrolysis of acetylsalicylic acid.

Place a crushed tablet of acetylsalicylic acid in a test tube and add 10 ml of water. Bring the contents of the tube to a boil and boil for 0.5-1 min. Filter the solution. Then 1-2 drops of iron(III) chloride solution are added to the resulting filtrate. What are you watching? Draw your own conclusions.

Write down the reaction equation:

Complete the work by filling out a table in which there are the following columns: operation performed, reagent, observations, output.

A violet color appears, indicating the release of salicylic acid containing a free phenolic group. As an ester, acetylsalicylic acid readily hydrolyzes when boiled with water.

Task for group 2

1. Consider the structural formulas of substances, name the functional groups.

2. Do the lab"Discovery of functional groups in the glucose molecule".

Goals: reinforce students' knowledge of qualitative reactions organic compounds, work out skills experimental definition functional groups.

Reagents and equipment: solution glucose, universal indicator, copper (II) sulfate solution, sodium hydroxide solution, alcohol lamp, test tube holder, matches, 10 ml measuring cylinder.

2.1. Pour 2 ml of glucose solution into a test tube. Using a universal indicator, infer the presence or absence of a carboxyl group.

2.2. Get copper (II) hydroxide: pour 1 ml of copper (II) sulfate into a test tube and add sodium hydroxide to it. Add 1 ml of glucose to the resulting precipitate, shake. What are you watching? What functional groups are characterized by this reaction?

2.3. Heat the mixture obtained in experiment No. 2. Mark the changes. Which functional group is characterized by this reaction?

2.4. Complete the work by filling out a table in which there are the following columns: operation performed, reagent, observations, output.

Demonstration experience. Interaction of glucose solution with ammonia solution of silver oxide.

Results of work:

- there is no carboxyl group, because the solution has a neutral reaction to the indicator;

- the precipitate of copper (II) hydroxide dissolves and a bright blue color appears, which is characteristic of polyhydric alcohols;

- when this solution is heated, a yellow precipitate of copper (I) hydroxide precipitates, which turns red on further heating, indicating the presence of an aldehyde group.

Conclusion. Thus, the glucose molecule contains a carbonyl and several hydroxyl groups and is an aldehyde alcohol.

Task for group 3

Physiological action ethanol

1. What is the effect of ethanol on living organisms?

2. Using the equipment and reagents on the table, demonstrate the effect of ethanol on living organisms. Comment on what you see.

Purpose of experience: to convince students that alcohol denatures proteins, irreversibly destroys their structure and properties.

Equipment and reagents: rack with test tubes, pipette, 10 ml graduated cylinder, egg white, ethanol, water.

Experience progress: Pour 2 ml of egg white into 2 test tubes. Add 8 ml of water to one, the same amount of ethanol to the other.

In the first tube, the protein dissolves and is well absorbed by the body. A dense white precipitate forms in the second test tube - proteins do not dissolve in alcohol, alcohol takes away water from proteins. As a result, the structure and properties of the protein, its functions are violated.

3. Tell us about the effect of ethyl alcohol on various organs and systems of human organs.

Discuss the effects of drinking alcohol on pregnant women.

Student performances.

Since ancient times, a large number of toxic substances have been known to man, all of them differ in the strength of their effect on the body. Among them, a substance stands out, which is known in medicine as a strong protoplasmic poison - this is ethyl alcohol. The death rate from alcoholism exceeds the number of deaths caused by all infectious diseases taken together.

Burning the mucous membrane of the mouth, pharynx, esophagus, it enters the gastrointestinal tract. Unlike many other substances, alcohol is quickly and completely absorbed in the stomach. Easily overcoming biological membranes, in about an hour it reaches its maximum concentration in the blood.

Alcohol molecules quickly penetrate biological membranes into the blood compared to water molecules. Ethyl alcohol molecules can easily cross biological membranes due to their small size, weak polarization, the formation of hydrogen bonds with water molecules, and the good solubility of alcohol in fats.

Quickly absorbed into the blood, dissolving well in the intercellular fluid, alcohol enters all cells of the body. Scientists have found that by disrupting the functions of cells, it causes their death: when drinking 100 g of beer, about 3000 brain cells die, 100 g of wine - 500, 100 g of vodka - 7500, contact of erythrocytes with alcohol molecules leads to coagulation of blood cells.

In the liver, the toxic substances that enter the blood are neutralized. Doctors call this organ a target for alcohol, since 90% of ethanol is neutralized in it. Occurs in the liver chemical processes ethanol oxidation.

We recall with students the stages of the process of alcohol oxidation:

Ethyl alcohol is oxidized to final decomposition products only if the daily consumption of ethanol does not exceed 20 g. If the dose is exceeded, then intermediate decomposition products accumulate in the body.

This leads to a number of negative side effects: increased formation of fat and its accumulation in liver cells; the accumulation of peroxide compounds capable of destroying cell membranes, as a result of which the contents of the cells flow out through the formed pores; very undesirable phenomena, the totality of which leads to the destruction of the liver - cirrhosis.

Acetic aldehyde is 30 times more toxic than ethyl alcohol. In addition, as a result of various biochemical reactions in tissues and organs, including the brain, the formation of tetrahydropapaverolin is possible, the structure and properties of which resemble well-known psychotropic drugs - morphine and canabinol. Doctors have proved that it is acetaldehyde that causes the occurrence of mutations and various deformities in embryos.

Acetic acid enhances the synthesis of fatty acids and leads to fatty degeneration of the liver.

Studying the physical properties of alcohols, we addressed the issue of changes in their toxicity in the homologous series of monohydric alcohols. With an increase in the molecular weight of the molecules of substances, their narcotic properties increase. If we compare ethyl and pentyl alcohols, then the molecular weight of the latter is 2 times greater, and toxicity - 20 times. Alcohols containing three to five carbon atoms form the so-called fusel oils, the presence of which in alcoholic beverages increases their toxic properties.

In this series, the exception is methanol - the strongest poison. When ingested 1-2 teaspoons of it affects the optic nerve, which leads to complete blindness, and the use of 30-100 ml leads to lethal outcome. The danger is heightened by the similarity of methyl alcohol to ethyl alcohol properties, appearance, smell.

Together with students, we try to find the cause of this phenomenon. They put forward various hypotheses. We dwell on the fact that the factors that increase the toxicity of methyl alcohol include the small size of molecules (high propagation speed), as well as the fact that the intermediate products of its oxidation - formic aldehyde and formic acid - are strong poisons.

Alcohol not neutralized by the liver and the toxic products of its decay again enter the bloodstream and are carried throughout the body, remaining in it for a long time. For example, in the brain, alcohol is found unchanged after 20 days after taking it.

We draw students' attention to how alcohol and its decay products are excreted from the body.

C 2 H 5 Oh

Unfortunately, in recent times alcohol consumption, like smoking, is common among women. The influence of alcohol on offspring goes in two directions.

First, the use of alcohol is accompanied by profound changes in the sexual sphere of both men and women. Alcohol and its decomposition products can affect both female and male reproductive cells even before fertilization - their genetic information(See Fig. "Healthy (1) and pathological (2) spermatozoa").

If the use of alcohol is prolonged, the activity of the reproductive system is disturbed, it begins to produce defective sex cells.

Secondly, alcohol directly affects the fetus. Constant use of 75-80 g of vodka, cognac or 120-150 g of weaker alcoholic beverages (beer) can cause fetal alcohol syndrome. Through the placenta, not only alcohol, but also its decomposition products, in particular acetaldehyde, which is ten times more dangerous than alcohol itself, enter the waters surrounding the fetus.

Alcohol intoxication has a detrimental effect on the fetus, because its liver, where blood from the placenta first of all enters, does not yet have a special enzyme that decomposes alcohol, and it, not neutralized, spreads throughout the body and causes irreversible changes. Alcohol is especially dangerous at the 7-11th week of pregnancy, when they begin to develop internal organs. It negatively affects their development, causing disturbances and changes. The brain is especially affected. Due to the influence of alcohol, dementia, epilepsy, neuroses, heart and kidney disorders can develop, external and internal genital organs are damaged.

Sometimes damage to the psyche and intellect is observed already in early childhood, but most often they are detected when children begin to learn. Such a child is intellectually weakened, aggressive. Alcohol affects the child's body much stronger than the body of an adult. Particularly sensitive and vulnerable nervous system and the child's brain.

So, let's look at the table "The influence of alcohol on the heredity and health of children" and draw conclusions .

The fate of children

Prolonged use of alcoholic beverages leads to softening of the cortical layer. Numerous petechial hemorrhages are observed; the transmission of excitation from one nerve cell to another is disrupted. Do not forget the laconic cautionary words of V. V. Mayakovsky:

Do not drink alcoholic beverages.

Drinkers - poison, others - torture.

Thus, you consolidated the ability to predict the chemical properties of unfamiliar organic substances, based on the knowledge of functional groups, repeated the physical and chemical properties of oxygen-containing organic substances, consolidated the ability to determine the belonging of organic compounds to classes of substances.

III. Homework.

1. Carry out transformations:

2. Explore possible reasons environmental pollution near production: methanol, phenol, formaldehyde, acetic acid. Analyze the impact of these substances on natural objects: the atmosphere, water sources, soil, plants, animals and humans. Describe first aid measures for poisoning