One of the most common chemical elements in the vast majority of chemicals is oxygen. Oxides, acids, bases, alcohols, phenols and other oxygen-containing compounds are studied in the course of inorganic and organic chemistry. In our article, we will study the properties, as well as give examples of their application in industry, agriculture and medicine.

Oxides

The simplest in structure are binary compounds of metals and non-metals with oxygen. The classification of oxides includes the following groups: acidic, basic, amphoteric and indifferent. The main criterion for the division of all these substances is which element combines with oxygen. If it is a metal, then they belong to the main ones. For example: CuO, MgO, Na 2 O - oxides of copper, magnesium, sodium. Their main chemical property is reaction with acids. So, copper oxide reacts with chloride acid:

CuO + 2HCl -> CuCl2 + H2O + 63, 3 kJ.

The presence of atoms of non-metallic elements in the molecules of binary compounds indicates their belonging to acidic hydrogen H 2 O, carbon dioxide CO 2, phosphorus pentoxide P 2 O 5. The ability of such substances to react with alkalis is their main chemical characteristic.

As a result of the reaction, species can be formed: acidic or medium. This will depend on how many moles of alkali reacts:

• CO2 + KOH => KHCO3;
• CO2 + 2KOH => K2CO3 + H2O.

Another group of oxygen-containing compounds, which include chemical elements such as zinc or aluminum, are referred to as amphoteric oxides. Their properties show a tendency towards chemical interaction with both acids and alkalis. The products of the interaction of acidic oxides with water are acids. For example, in the reaction of sulfuric anhydride and water, Acids are formed - this is one of the most important classes of oxygen-containing compounds.

Acids and their properties

Compounds consisting of hydrogen atoms bonded to complex ions of acid residues are acids. They can be conventionally divided into inorganic, for example, carbonic acid, sulfate, nitrate, and organic compounds. The latter include acetic acid, formic acid, oleic acid. Both groups of substances have similar properties. So, they enter into a neutralization reaction with bases, react with salts and basic oxides. Almost all oxygen-containing acids in aqueous solutions dissociate into ions, being a conductor of the second kind. It is possible to determine the acidic nature of their environment, due to the excessive presence of hydrogen ions, using indicators. For example, purple litmus turns red when added to an acid solution. A typical organic compound is acetic acid containing a carboxyl group. It includes a hydrogen atom, which causes acidic It is a colorless liquid with a specific pungent odor, crystallizing at temperatures below 17 ° C. CH 3 COOH, like other oxygen-containing acids, is perfectly soluble in water in any proportion. Its 3 - 5% solution is known in everyday life under the name of vinegar, which is used in cooking as a seasoning. The substance has also found its application in the production of acetate silk, dyes, plastics and some medicines.

Organic compounds containing oxygen

In chemistry, a large group of substances can be distinguished, containing, in addition to carbon and hydrogen, also oxygen particles. These are carboxylic acids, esters, aldehydes, alcohols and phenols. All their chemical properties are determined by the presence in the molecules of special complexes - functional groups. For example, an alcohol containing only limiting bonds between atoms - ROH, where R is a hydrocarbon radical. These compounds are usually considered as derivatives of alkanes, in which one hydrogen atom is replaced by a hydroxyl group.

Physical and chemical properties of alcohols

The aggregate state of alcohols is liquid or solid compounds. There are no gaseous substances among alcohols, which can be explained by the formation of associates - groups consisting of several molecules connected by weak hydrogen bonds. This fact also determines the good solubility of lower alcohols in water. However, in aqueous solutions, oxygen-containing organic substances - alcohols, do not dissociate into ions, do not change the color of indicators, that is, they have a neutral reaction. The hydrogen atom of the functional group is weakly bound to other particles, therefore, in chemical interactions it is able to leave the limits of the molecule. At the place of free valence, it is replaced by other atoms, for example, in reactions with active metals or with alkalis, by metal atoms. In the presence of catalysts, such as a platinum net or copper, alcohols are oxidized by vigorous oxidants - potassium dichromate or permanganate, to aldehydes.

Esterification reaction

One of the most important chemical properties of oxygen-containing organic substances: alcohols and acids is a reaction that leads to the production of esters. It is of great practical importance and is used in industry for the extraction of esters used as solvents in the food industry (in the form of fruit essences). In medicine, some of the esters are used as antispasmodics, for example, ethyl nitrite dilates peripheral blood vessels, and isoamyl nitrite is a protector of coronary artery spasms. The equation for the esterification reaction is as follows:

CH3COOH + C2H5OH<--(H2SO4)-->CH3COOC2H5 + H2O

In it, CH 3 COOH is acetic acid, and C 2 H 5 OH is the chemical formula of ethanol alcohol.

Aldehydes

If the compound contains a functional group -COH, then it belongs to aldehydes. They are presented as products of further oxidation of alcohols, for example, by oxidizing agents such as copper oxide.

The presence of a carbonyl complex in the molecules of formic or acetic aldehyde determines their ability to polymerize and attach atoms of other chemical elements. Qualitative reactions that can be used to prove the presence of a carbonyl group and the belonging of a substance to aldehydes are the reaction of a silver mirror and interaction with copper hydroxide when heated:

The most widely used acetaldehyde is used in industry for the production of acetic acid - a large tonnage product of organic synthesis.

Properties of oxygen-containing organic compounds - carboxylic acids

The presence of a carboxyl group - one or more - is a distinctive feature of carboxylic acids. Due to the structure of the functional group, dimers can form in acid solutions. They are linked by hydrogen bonds. Compounds dissociate into hydrogen cations and acid residue anions and are weak electrolytes. The exception is the first representative of a series of saturated monobasic acids - formic, or methane, which is a medium-strength conductor of the second kind. The presence of only simple sigma bonds in molecules indicates the limit, but if substances have double pi bonds in their composition, these are unsaturated substances. The first group includes acids such as methane, acetic, butyric. The second is represented by compounds that are part of liquid fats - oils, for example, oleic acid. The chemical properties of oxygen-containing compounds: organic and inorganic acids are very similar. So, they can interact with active metals, their oxides, with alkalis, as well as with alcohols. For example, acetic acid reacts with sodium, oxide and with the formation of a salt - sodium acetate:

NaOH + CH3COOH → NaCH3COO + H2O

A special place is occupied by compounds of higher carboxylic oxygen-containing acids: stearic and palmitic, with a trihydric saturated alcohol - glycerol. They are esters and are called fats. The same acids are part of sodium and potassium salts as an acid residue, forming soaps.

Fats are important organic compounds that are widespread in nature and play a leading role as the most energy-consuming substance. They are not an individual compound, but a mixture of dissimilar glycerides. These are compounds of a saturated polyhydric alcohol - glycerol, which, like methanol and phenol, contains hydroxyl functional groups. Fats can be subjected to hydrolysis - heating with water in the presence of catalysts: alkalis, acids, zinc oxides, magnesium. The reaction products are glycerin and various carboxylic acids, which are later used for the production of soap. In order not to use expensive natural carboxylic acids in this process, they are obtained by oxidizing paraffin.

Phenols

Finishing the consideration of the classes of oxygen-containing compounds, let us dwell on phenols. They are represented by the phenyl radical —C 6 H 5, attached to one or more functional hydroxyl groups. The simplest representative of this class is carbolic acid, or phenol. As a very weak acid, it can interact with alkalis and active metals - sodium, potassium. A substance with pronounced bactericidal properties - phenol is used in medicine, as well as in the production of dyes and phenol-formaldehyde resins.

In our article, we studied the main classes of oxygen-containing compounds, and also considered their chemical properties.

The composition of oxygen-containing compounds can include hydroxyl, carbonyl and carboxyl groups. They correspond to the class of compounds - alcohols, aldehydes, ketones, carboxylic acids.

Alcohols

Let's act on ethylene with water. Sulfuric acid is used as a catalyst. It catalyzes both the attachment and the withdrawal of water. As a result of the breaking of the double bond, one carbon atom will attach a hydrogen atom, and the other - the hydroxyl group of the water molecule. This is how compounds of the alcohol class are obtained.

The simplest alcohol is methyl CH3 – OH. Ethyl alcohol is the next homologue of a number of alcohols.

If the alcohol molecule contains one hydroxyl group, such an alcohol is called monohydric. There are also alcohols that contain two or more hydroxyl groups. Such alcohols are called polyhydric. An example of a polyhydric alcohol is the commonly known glycerin.

Aldehydes

Under the action of a weak oxidizing agent, a hydroxyl group can be converted to a carbonyl group. As a result, a new class of compounds is formed - aldehydes. For example, ethyl alcohol is oxidized by such a weak oxidizing agent as copper (II) oxide. The reaction takes place when heated. The reaction product is acetaldehyde.

This is a qualitative reaction to alcohols. It is produced like this. The copper wire is calcined to form an oxide film and dipped in a red-hot state in alcohol. Alcohol is oxidized and copper is reduced. The copper wire becomes shiny and gives off the smell of acetaldehyde.

Like alcohols, aldehydes are capable of being oxidized by weak oxidants. This reaction occurs when the aldehyde is oxidized with an ammoniacal solution of silver oxide. The precipitated silver forms the thinnest mirror layer on the walls of the test tube. This process is called the silver mirror reaction. It is used for the qualitative determination of aldehydes.

Carboxylic acids

During the oxidation of aldehydes, the carbonyl group attaches an oxygen atom. This is how a carboxyl group is formed. A new class of organic compounds is formed - carboxylic acids. In our case, acetic acid was obtained from acetaldehyde. As you can see, functional groups can transform into each other.

Many carboxylic acids are weak electrolytes. During dissociation under the influence of water molecules, hydrogen is split off from the carboxyl group of the organic acid molecule:

CH3COOH ó CH3COO- + H +

Acetic acid, like other organic acids, reacts with bases, basic oxides, and metals.

Aldehydes, alcohols and acids are essential in our lives. They are used for the synthesis of various substances. Alcohols are used to obtain synthetic rubbers, fragrances, drugs, dyes, and as solvents.

Organic acids are widespread in nature and play an important role in biochemical reactions. In the chemical industry, organic acids are used in leather production, in calico printing.

Alcohols are also poisonous. Methanol is especially toxic. When ingested, it causes blindness and even death of a person. Ethyl alcohol has a negative effect on vital centers in the cerebral cortex, blood vessels, on the psyche, destroying a person's personality.

Target: develop the ability to conduct observations and draw conclusions, write down the equations of the corresponding reactions in molecular and ionic forms .

Occupation security

1. A collection of guidelines for students on the implementation of practical exercises and laboratory work in the discipline "Chemistry".

2. Sodium hydroxide solution, sodium carbonate, calcium carbonate, copper (II) oxide, acetic acid, litmus blue, zinc; test tube rack, water bath, heating device, matches, test tube holder.

Theoretical material

Carboxylic acids are organic compounds, the molecules of which contain one or more carboxyl groups connected to a hydrocarbon radical or a hydrogen atom.

Obtaining: In the laboratory, carboxylic acids can be obtained from their salts by acting on them with sulfuric acid when heated, for example:

2СН 3 - СООNa + H 2 SO 4 ® 2СН 3 - СООН + Na 2 SO 4
In industry, they are obtained by oxidation of hydrocarbons, alcohols and aldehydes.

Chemical properties:
1. Due to the shift of the electron density from the hydroxyl group O – H to strongly

polarized carbonyl group C = O, carboxylic acid molecules are capable of

electrolytic dissociation: R – COOH → R – COO - + H +

2.Carboxylic acids have properties characteristic of mineral acids. They react with active metals, basic oxides, bases, salts of weak acids. 2СH 3 COOH + Mg → (CH 3 COO) 2 Mg + H 2

2СH 3 COOH + СaO → (CH 3 COO) 2 Ca + H 2 O

H – COOH + NaOH → H – COONa + H 2 O

2СH 3 CH 2 COOH + Na 2 CO 3 → 2CH 3 CH 2 COONa + H 2 O + CO 2

CH 3 CH 2 COOH + NaHCO 3 → CH 3 CH 2 COONa + H 2 O + CO 2

Carboxylic acids are weaker than many strong mineral acids

CH 3 COONa + H 2 SO 4 (conc.) → CH 3 COOH + NaHSO 4

3. Formation of functional derivatives:

a) when interacting with alcohols (in the presence of concentrated H 2 SO 4), esters are formed.

The formation of esters by the interaction of an acid and an alcohol in the presence of mineral acids is called an esterification reaction. CH 3 - –OH + HO – CH 3 D CH 3 - –OCH 3 + H 2 O

acetic acid methyl methyl ester

acetic acid alcohol

The general formula of esters is R– –OR ’where R and R" are hydrocarbon radicals: in formic acid esters — formates —R ​​= H.

The reverse reaction is hydrolysis (saponification) of the ester:

CH 3 - –OCH 3 + HO – H DCH 3 - –OH + CH 3 OH.

Glycerin (1,2,3-trihydroxypropane; 1,2,3-propanetriol) (glycos - sweet) chemical compound with the formula HOCH2CH (OH) -CH2OH or C3H5 (OH) 3. The simplest representative of trihydric alcohols. It is a viscous transparent liquid.

Glycerin is a colorless, viscous, hygroscopic liquid, infinitely soluble in water. Sweet taste (glycos - sweet). It dissolves many substances well.

Glycerin is esterified with carboxylic and mineral acids.

Esters of glycerin and higher carboxylic acids are fats.

Fats - these are mixtures of esters formed by the trihydric alcohol, glycerol and higher fatty acids. General formula of fats, where R are radicals of higher fatty acids:

Most often, the composition of fats includes saturated acids: palmitic C15H31COOH and stearic C17H35COOH, and unsaturated acids: oleic C17H33COOH and linoleic C17H31COOH.

The general name for compounds of carboxylic acids with glycerol is triglycerides.

b) when exposed to dehydrating reagents as a result of intermolecular

dehydration anhydrides are formed

CH 3 - –OH + HO– –CH 3 → CH 3 - –O– –CH 3 + H 2 O

Halogenation. Under the action of halogens (in the presence of red phosphorus), α-halogenated acids are formed:

Application: in the food and chemical industries (production of cellulose acetate, from which acetate fiber, organic glass, film is obtained; for the synthesis of dyes, medicines and esters).

Questions to consolidate theoretical material

1 What organic compounds are carboxylic acids?

2 Why are there no gaseous substances among carboxylic acids?

3 What causes the acidic properties of carboxylic acids?

4 Why does the color of the indicators in the acetic acid solution change?

5 What chemical properties do glucose and glycerin have in common, and how do these substances differ from each other? Write down the equations of the corresponding reactions.

Exercise

1. Review the theoretical material on the topic of the practical lesson.

2. Answer questions to consolidate the theoretical material.

3. Investigate the properties of oxygen-containing organic compounds.

4. Prepare a report.

Instructions for implementation

1. Read the safety rules for working in a chemical laboratory and sign the TB journal.

2. Perform experiments.

3. Enter the results in the table.

Experience no. 1 Test of acetic acid solution with litmus

Dilute the resulting acetic acid with a little water and add a few drops of blue litmus or dip indicator paper into the test tube.

Experience no. 2 Reaction between acetic acid and calcium carbonate

Pour some chalk (calcium carbonate) into a test tube and add a solution of vinegar

Experiment No. 3 Properties of glucose and sucrose

a) Add 5 drops of glucose solution, a drop of copper (II) salt solution to a test tube and, while shaking, a few drops of sodium hydroxide solution until a light blue solution is formed. This experiment was done with glycerin.

b) Heat the resulting solutions. What are you watching?

Experience No. 4 Qualitative reaction to starch

Add a drop of iodine alcohol solution to 5-6 drops of starch paste in a test tube.

Sample report

Laboratory work No. 9 Chemical properties of oxygen-containing organic compounds.

Purpose: to form the ability to conduct observations and draw conclusions, write down the equations of the corresponding reactions in molecular and ionic forms .

Conclusion to be made in accordance with the purpose of the work

Literature 0-2 s. 94-98

Laboratory work No. 10

Alcohols- derivatives of hydrocarbons containing a functional group HE(hydroxyl). Alcohols in which there is one OH group are called monoatomic, and alcohols with several OH groups - polyatomic.

The names of some common alcohols are given in table. nine.

Alcohols are distinguished by structure primary, secondary and tertiary, depending on which carbon atom (primary, secondary or tertiary) is the OH group:

Monohydric alcohols are colorless liquids (up to Cl 2 H 25 OH), soluble in water. The simplest alcohol - methanol CH 3 OH is extremely toxic. With an increase in molar mass, the boiling point of alcohols rises.

Molecules of liquid monohydric alcohols ROH are associated through hydrogen bonds:

(these bonds are analogous to hydrogen bonds in pure water).

When dissolved in water, ROH molecules form hydrogen bonds with water molecules:

Aqueous solutions of alcohols ROH have a neutral medium; in other words, alcohols practically do not dissociate in an aqueous solution either in an acidic or in a basic manner.

The chemical properties of monohydric alcohols are due to the presence of the OH functional group in them.

Hydrogen of the OH group in alcohols can be replaced by a metal:

Ethanolates and derivatives of other alcohols (alcoholates) easily hydrolyzed:

The OH group in alcohols can be replaced by Cl or Br:

When dehydrating agents act on alcohols, for example, concentrated H 2 SO 4, intermolecular dehydration:

Reaction product - diethyl ether(C 2 H 5) 2 O - belongs to the class ethers.

In more severe conditions, dehydration becomes intramolecular and the corresponding alkene is formed:

Polyhydric alcohols Consider the example of the simplest representatives of di- and trihydric alcohols:

At room temperature, they are colorless viscous liquids with boiling points of 198 and 290 ° C, respectively, and are infinitely miscible with water. Ethylene glycol is poisonous.

The chemical properties of polyhydric alcohols are similar to those of ROH alcohols. So, in ethylene glycol, one or two OH groups can be replaced by halogen:

The acidic properties of polyhydric alcohols are manifested in the fact that (in contrast to monohydric alcohols) the hydrogen of the OH group is replaced by a metal under the action of not only metals, but also metal hydroxides:

(arrows in the formula for copper glycolate show the formation of covalent copper - oxygen bonds by the donor-acceptor mechanism).

Glycerin reacts similarly with copper (II) hydroxide:

Glycolate and glycerate of copper (II), which have a bright blue color, allow high-quality find polyhydric alcohols.

Receiving monohydric alcohols in industry- hydration of alkenes in the presence of catalysts (H 2 SO 4, Al 2 O 3), and the addition of water to asymmetric alkenes occurs according to the Markovnikov rule:

(a method of obtaining a secondary alcohol), or the addition of CO and H 2 to alkenes in the presence of a cobalt catalyst (the process is called hydroforming):

(method of obtaining primary alcohol).

V laboratories(and sometimes in industry) alcohols are obtained by the interaction of halogenated hydrocarbons with water or an aqueous alkali solution when heated:

Ethanol C 2 H 5 OH is also formed when alcoholic fermentation sugary substances such as glucose:

Ethylene glycol is produced in a two-step process:

a) ethylene oxidation:

b) hydration of ethylene oxide:

Glycerin was previously obtained by saponification of fats (see 20.3), the modern three-stage method is the gradual oxidation of propene (only a diagram of the process is shown):

Alcohols are used as raw materials in organic synthesis, as solvents (for varnishes, paints, etc.), as well as in the paper, printing, perfumery, pharmaceutical and food industries.

Ethers- a class of organic compounds containing a bridging oxygen atom - O– between two hydrocarbon radicals: R - O-R ". The most famous and widely used ether is diethyl ether C 2 H 5 -O - C 2 H 5. A colorless, easily mobile liquid with a characteristic ("ethereal") odor, in laboratory practice it is simply called ether. Almost immiscible with water, bale t = 34.51 ° C. Ether vapor ignites in air. Get diethyl ether at intermolecular dehydration of ethanol (see above), the main application is a solvent.

Phenols- these are alcohols in which the OH group is directly linked to the benzene ring. The simplest representative is phenol C 6 H 5 -OH. White (turning pink in the light) crystals with a strong odor, melting point = 41 ° C. Causes skin burns, is poisonous.

Phenol is characterized by a significantly higher acidity than acyclic alcohols. As a result, phenol in aqueous solution easily reacts with sodium hydroxide:

Hence the trivial name for phenol - carbolic acid.

Note that the OH group in phenol is never replaced by any other groups or atoms, but does more mobile hydrogen atoms of the benzene ring. Thus, phenol easily reacts with bromine in water and nitric acid, forming 2,4,6-tribromophenol (I) and 2,4,6-trinitrophenol, respectively (II, traditional name - picric acid):

Phenol in industry obtained by heating chlorobenzene with sodium hydroxide solution under pressure at 250 ° C:

Phenol is used as a raw material for the production of plastics and resins, intermediates for the paint and varnish and pharmaceutical industries, as a disinfectant.

10.2. Aldehydes and ketones

Aldehydes and ketones Are derivatives of hydrocarbons containing a functional carbonyl group CO... In aldehydes, the carbonyl group is bonded to a hydrogen atom and one radical, and in ketones to two radicals.

General formulas:

The names of common substances of these classes are given in table. ten.

Methanal is a colorless gas with a pungent suffocating odor, readily soluble in water (the traditional name for a 40% solution is formalin), poisonous. Subsequent members of the homologous series of aldehydes are liquids and solids.

The simplest ketone is propanone-2, better known as acetone, at room temperature - a colorless liquid with a fruity odor, bale = 56.24 ° C. Mixes well with water.

The chemical properties of aldehydes and ketones are due to the presence of the CO carbonyl group; they easily enter into reactions of addition, oxidation and condensation.

As a result joining hydrogen to aldehydes formed primary alcohols:

Reduction with hydrogen ketones formed secondary alcohols:

Reaction joining sodium hydrosulfite is used for the isolation and purification of aldehydes, since the reaction product is slightly soluble in water:

(the action of dilute acids converts such products into aldehydes).

Oxidation aldehydes pass easily under the influence of atmospheric oxygen (products are the corresponding carboxylic acids). Ketones are relatively stable to oxidation.

Aldehydes are able to participate in reactions condensation... Thus, the condensation of formaldehyde with phenol proceeds in two stages. Initially, an intermediate product is formed, which is phenol and alcohol at the same time:

The intermediate then reacts with another phenol molecule to form the product polycondensation -phenol formaldehyde resin:

Qualitative reaction to the aldehyde group - the reaction of the "silver mirror", ie, the oxidation of the C (H) O group with silver (I) oxide in the presence of ammonia hydrate:

The reaction with Cu (OH) 2 proceeds in a similar way; upon heating, a red precipitate of copper (I) oxide Cu 2 O appears.

Receiving: the general method for aldehydes and ketones is dehydrogenation(oxidation) of alcohols. With dehydrogenation primary alcohols get aldehydes, and in the dehydrogenation of secondary alcohols - ketones... Typically, dehydrogenation occurs when heated (300 ° C) over finely crushed copper:

In the oxidation of primary alcohols strong oxidizing agents (potassium permanganate, potassium dichromate in an acidic environment), the process is difficult to stop at the stage of obtaining aldehydes; aldehydes are easily oxidized to the corresponding acids:

A more suitable oxidizing agent is copper (II) oxide:

Acetaldehyde in industry get by the Kucherov reaction (see 19.3).

The most widely used aldehydes are methanal and ethanal. Methanal used for the production of plastics (phenoplastics), explosives, varnishes, paints, medicines. Ethanal- the most important intermediate product in the synthesis of acetic acid and butadiene (production of synthetic rubber). The simplest ketone - acetone is used as a solvent for various varnishes, cellulose acetates, in the production of film and explosives.

10.3. Carboxylic acids. Esters. Fats

Carboxylic acids are derivatives of hydrocarbons containing the functional group COOH ( carboxyl).

Formulas and titles some common carboxylic acids are given in table. eleven.

Traditional names of acids НСООН ( formic), CH 3 COOH (acetic), C 6 H 5 COOH (benzoic) and (COOH) 2 (oxalic) it is recommended to use them instead of their systematic names.

Formulas and titles acid residues are given in table. 12.

For the names of the salts of these carboxylic acids (as well as their esters, see below), traditional names are commonly used, for example:

Lower carboxylic acids are colorless liquids with a pungent odor. As the molar mass increases, the boiling point increases.

Carboxylic acids are found in nature:

The simplest carboxylic acids are soluble in water, reversibly dissociate in an aqueous solution with the formation of hydrogen cations:

and exhibit the general properties of acids:

The interaction of carboxylic acids with alcohols is of great practical importance (see below for more details):

Note that HCOOH acid enters into the “silver mirror” reaction as aldehydes:

and decomposes under the action of dehydrating agents:

Receiving:

Oxidation of aldehydes:

Oxidation of hydrocarbons:

In addition, formic acid is obtained according to the following scheme:

and acetic acid - according to the reaction:

Apply formic acid as a mordant for dyeing wool, fruit juice preservative, bleach, disinfectant. Acetic acid used as a raw material in the industrial synthesis of dyes, medicines, acetate fiber, incombustible film, organic glass. Sodium and potassium salts of higher carboxylic acids are the main components of soap.

Esters- products of the exchange interaction of carboxylic acids with alcohols. This interaction is called a reaction. esterification:

The esterification reaction mechanism was established using an alcohol labeled with the 18 O isotope; this oxygen after the reaction was in the composition ether(not water):

Therefore, in contrast to the reaction of neutralization of an inorganic acid with an alkali (H + + OH - = H 2 O), in the esterification reaction, the carboxylic acid always gives up the group HE, alcohol - atom H(water is formed). The esterification reaction is reversible; it flows better in acidic environment, the reverse reaction ( hydrolysis, saponification)- in an alkaline environment.

Formulas and titles common esters are given in table. 13.

Among the esters, there are colorless, low-boiling, flammable liquids with a fruity odor, for example:

Esters are used as solvents for varnishes, paints and cellulose nitrates, carriers of fruit aromas in the food industry.

Esters of trihydric alcohol - glycerol and higher carboxylic acids (in the general form RCOOH), for example with formulas and names:

are named fat. An example of a fat would be a mixed ester of glycerol and these acids:

The higher the content of residues of oleic acid (or other unsaturated acids), the lower the melting point of the fat. Fats that are liquid at room temperature are called oils. By hydrogenation, that is, the addition of hydrogen to the double bond, oils are converted into solid fats (for example, vegetable oil - into margarine). The esterification (fat formation) reaction is reversible:

A direct reaction goes better in acidic environment, the reverse reaction - hydrolysis, or saponification, fat - in alkaline environment; during digestion, fat is saponified (broken down) with the help of enzymes.

10.4. Carbohydrates

Carbohydrates (Sahara) - the most important natural compounds, consisting of carbon, hydrogen and oxygen. Carbohydrates are classified into monosaccharides, disaccharides, and polysaccharides. Monosaccharides do not undergo hydrolysis, and the rest of the carbohydrates, when boiled in the presence of acids, are split into monosaccharides.

Monosaccharides(and all other carbohydrates) are polyfunctional compounds. The monosaccharide molecule contains functional groups of different types: groups HE(alcohol function) and groups CO(aldehyde or ketone function). Therefore, distinguish aldoses(aldehyde alcohols, alcohol aldehydes) and ketosis(ketone alcohols, alcohol ketones).

The most important representative of aldoses is glucose:

and a representative of ketosis - fructose:

Glucose (grape sugar) and fructose (fruit sugar) are structural isomers, their molecular formula is C 6 H 12 O 6.

Glucose can be distinguished from fructose in the same way as any aldehyde from a ketone - by the "silver mirror" reaction in an ammonia solution of Ag 2 O:

Esterification of glucose and fructose (for example, acetic acid) leads to the formation of esters for all five OH groups (replaced by OOCH 3).

However, not all reactions characteristic of aldehydes occur with glucose; for example, there is no addition reaction involving sodium hydrosulfite. The reason is that the glucose molecule can exist in three isomeric forms, of which two forms (? And?) - cyclical... In solution, all three forms are in equilibrium, and the open (aldehyde) form given above is contained in the smallest quantity:

Cyclic forms of glucose do not contain an aldehyde group. They differ from each other only in the spatial arrangement of the H atom and the OH group at the C 1 carbon atom (next to oxygen in the cycle):

Disaccharides are formed from two molecules of monosaccharides by intermolecular dehydration. So, sucrose(normal sugar) C 12 H 22 O 11 is a product of the combination of glucose and fructose residues due to the elimination of water:

During hydrolysis in an acidic medium, sucrose is again converted into monosaccharides:

The resulting mixture is invert sugar- contained in honey. At 200 ° C sucrose, losing water, turns into a brown mass (caramel).

Polysaccharides - starch and cellulose (fiber) - the products of polycondensation (intermolecular dehydration), respectively, of the α- and β-forms of glucose, their general formula is (С 6 Н 10 О 5) n. The degree of polymerization of starch is 1000–6000, and cellulose is 10,000–14,000. Cellulose is the most widespread organic substance in nature (in wood, the mass fraction of cellulose reaches 75%). Starch (lighter) and cellulose (harder) undergo hydrolysis (conditions: H 2 SO 4 or HCl,> 100 ° C); the end product is glucose.

Esters of cellulose with acetic acid are of great practical importance:

They are used in the production of artificial acetate fiber and film.

Examples of tasks of parts A, B

1-2. To connect with the formula

the correct name is

1) 2-methylpropanol-2

2) 2,2-dimethylethanol

3) propylethyl ether

4) ethyl propyl ether

3-4. To connect with the formula

the correct name is

1) 1,1-dimethylpropanoic acid

2) 3-methylbutanoic acid

3) 2-methylpropanal

4) dimethylethanal

5. The correct name of the substance CH 3 COOCH 2 CH 3 is

1) methyl acetate

2) ethyl acetate

3) methyl formate

4) ethyl formate

6. Hydrogen bonds are formed between molecules of compounds

3) acetic acid

4) acetaldehyde

7. For the composition C 4 H 8 O 2, the names of structural isomers from the class of esters are

1) propyl formate

2) diethyl ether

3) ethyl acetate

4) methyl propionate

8-11. Compound formula with name

8.sucrose

9.starch

10.fructose

11. fiber

corresponds to the composition

1) C 6 H 12 O 6

2) (C 6 H 10 O 5) n

3) Cl 2 H 22 O n

12. For saturated monohydric alcohols, characteristic reactions are

1) hydrolysis

2) hydration

3) esterification

4) dehydration

13. The molecule of the final product of the reaction between phenol and bromine in water contains the total number of atoms of all elements equal to

14-17. In the reaction equation

14.oxidation of ethanol with copper (II) oxide

15.phenol bromination

16.Intermolecular dehydration of ethanol

17.nitration of phenol

the sum of the coefficients is

18.In the esterification reaction, the OH group is cleaved from the molecule

2) aldehyde

4) acids

19.With the help of chlorophyll in a green plant,

1) oxygen

3) glucose

20-21. The chemical properties of glucose, characteristic of

20.alcohols

21.aldehydes

manifest in reaction

1) alcoholic fermentation

2) "silver mirror"

3) esterification

4) neutralization

22-24. When heated with water in the presence of H 2 SO 4 carbohydrates

22. starch

23. cellulose

24. sucrose

after the end of hydrolysis get

2) fructose

3) gluconic acid

4) glucose

25. Methods for producing ethanol are

1) hydration of ethene

2) fermentation of glucose

3) recovery of ethanal

4) oxidation of ethanal

26. Methods for producing ethylene glycol are

1) oxidation of ethene

2) hydration of ethene

3) the action of alkali on 1,2-C 2 H 4 Cl 2

4) hydration of ethine

27. Methods for obtaining formic acid are

1) methane oxidation

2) oxidation of phenol

3) oxidation of methanol

4) the reaction of CH 3 OH with CO

28. For the synthesis of acetic acid, compounds are used

1) C 2 H 5 OH

29. Methanol is used in production

1) plastics

2) rubbers

3) gasoline

4) fats and oils

30. To recognize phenol (mixed with 1-butanol) use

1) indicator and alkali solution

2) bromine water

3) copper (II) hydroxide

4) ammonia solution of silver oxide (I)

31. The same reagent is suitable for the recognition of glycerin, acetic acid, acetaldehyde and glucose in their solutions

3) H 2 SO 4 (conc.)

4) Ag 2 O (in solution NH 3)

32. Organic matter - a product of acetylene hydration, which enters into a "silver mirror" reaction, and upon reduction forms ethanol, is

1) acetaldehyde

2) acetic acid

33. Products A, B, and C in the reaction scheme CO 2 + H 2 O> photosynthesis A> fermentation - CO 2 B> HCOOH B

- this is accordingly

2) glucose

3) propanoic acid

4) ethyl formate

34. Phenol will participate in the processes:

1) dehydration

2) bromination

3) isomerization

4) neutralization

5) nitration

6) "silver mirror"

35. The course of reactions is possible:

1) solid fat + hydrogen> ...

2) formic acid + formaldehyde> ...

3) methanol + copper (II) oxide> ...

4) sucrose + water (in conc. H 2 SO 4)> ...

5) methanal + Ag 2 O (in solution NH 3)> ...

6) ethylene glycol + NaOH (solution)> ...

36. For the industrial synthesis of phenol-formaldehyde resin, you should take a set of reagents

1) C 6 H 6, HC (H) O

2) C 6 H 6, CH 3 C (H) O

3) C 6 H 5 OH, HC (H) O

4) C 6 H 5 OH, CH 3 C (H) O

Goals. To acquaint with a large group of organic substances genetically related to each other (structure, isomerism, nomenclature, physical properties, classification); to form a general idea of ​​alcohols, aldehydes, carboxylic acids; continue the development of general educational skills; to educate the need for knowledge about those substances with which we come in contact in everyday life - they are found in food products, medicines.

Demonstration material. Collection of carboxylic acids, alcohols, phenol, formalin.

Demonstration experiment. Study of the water solubility of alcohols (ethanol,n-propanol and n -butanol), acids (formic, acetic, propionic, butyric, stearic and palmitic), aldehydes (40% formic aldehyde solution - formalin).

Visual support. Tables "Formation of hydrogen bonds", "Alcohols and aldehydes"; molecular models; pictures with the formulas of the most common acids.

Handout. Information card for the lesson.

Intersubject and intrasubject communications. Inorganic chemistry: mineral acids, hydrogen bonds between molecules; organic chemistry: hydrocarbons (general formulas, structure, nomenclature, isomerism); mathematics: function; physics: physical properties of substances, constants.

DURING THE CLASSES

Examples: formic acid, oxalic acid, citric, malic, lactic acids, "wine alcohol" (ethanol), formalin (40% solution of formic aldehyde in water), glycerin, acetone, ether for anesthesia ( diethyl ether), phenol.

Exercise 1. Divide the following substances into three groups - alcohols, aldehydes, carboxylic acids:

Task 2. What are the criteria for classifying oxygen-containing compounds? What are the functional groups of alcohols, aldehydes and carboxylic acids?

Functional groups of substances of different classes

Alcohols

Aldehydes

Carboxylic acids

HE

hydroxyl

Task 3. What is the name of the hydrocarbon fragment in the formulas of organic oxygen-containing compounds? For example, in task 1 (see above) these are fragments: CH 3, C 4 H 9, C 5 H 11, C 2 H 5, C 7 H 15, C 3 H 7.

Denoting the hydrocarbon radical by the letter R, we obtain the general formulas:

alcohols - ………………………. ;

aldehydes - ……………… ..;

organic acids - …………………. ...

The classification of alcohols, aldehydes and acids can be carried outby the number of functional groups in molecules. There are one-, two- and trihydric alcohols:

Aldehydes with two CHO aldehyde groups in the molecule are called as follows:

Carboxylic acids, depending on the number of carboxyl groups in the molecule, are mono-, di- and tri-basic:

Oxygenated compounds varyby the structure of the hydrocarbon radical. They are limiting (saturated), unsaturated (unsaturated), cyclic, aromatic.

Examples of alcohols:

Examples of aldehydes:

Examples of carboxylic acids:

We will only study saturated monobasic carboxylic acids, monohydric alcohols and aldehydes.

Task 4. Give the definition of saturated alcohols, aldehydes, carboxylic acids.

Alcohols are primary, secondary and tertiary. In primary alcohols, at the C atom bonded to the OH hydroxyl group, there is one carbon neighbor; in secondary alcohols at the C atom, along with the OH group, there are two carbon substituents (neighbors), and in tertiary alcohols, there are three carbon substituents. For example:

Nomenclature
oxygenated compounds

According to the IUPAC international nomenclature, the names of alcohols are derived from the names of the corresponding alkanes with the addition of the "ol" suffix.

Task 5. Write down the molecular formulas and names for four primary alcohols with 4 or more carbon atoms.

The peculiarity of the names of aldehydes is the suffix "al".

Task 6. Enter the IUPAC formulas and names of the following four aldehydes in the table.

Task 7. Write down the IUPAC formulas and names for the following four acids in the table.

Task 8. Why can't methanal and methanoic acid be considered homologues? How do they differ from homologues?

Physical properties.
Hydrogen bond

1) Aggregate state of linear connections of different classes.

Task 9. Why are there so many gases among alkanes? Why does gaseous aldehyde exist under normal conditions (0 ° C, 1 atm)? With what it can be connected?

2) Temperature of foam (° C) of the first five homologues of substances of four classes.

Task 10. Compare the boiling points of the corresponding (by the number of C atoms) alkanes, alcohols, aldehydes and carboxylic acids. What are the features of this characteristic for substances of different homologous series?

3) A hydrogen bond in the series of compounds under consideration is an intermolecular bond between the oxygen of one molecule and the hydroxyl hydrogen of another molecule.

Reference information - electronegativity of atoms: C - 2.5; H - 2.1; About - 3.5.

The distribution of electron density in the molecules of alcohols and carboxylic acids is uneven:

The hydrogen bond in alcohols and acids is depicted as follows:

Conclusion. In the homologous series of alcohols and carboxylic acids, gaseous substances are absent and the boiling points of substances are high. This is due to the presence of hydrogen bonds between molecules. Due to hydrogen bonds, the molecules turn out to be associated (as if cross-linked), therefore, in order for the molecules to become free and acquire volatility, it is necessary to spend additional energy to break these bonds.

4) The solubility in water is demonstrated experimentally by the example of the solubility in water of alcohols - ethyl, propyl, butyl and acids - formic, acetic, propionic, butyric and stearic. A solution of formic aldehyde in water is also demonstrated.

Task 11. What can be said about the solubility of alcohols, aldehydes and carboxylic acids in water? What explains the solubility of these substances?

When answering, use the scheme for the formation of hydrogen bonds between acid and water molecules:

It should be noted that with an increase in molecular weight, the water solubility of alcohols and acids decreases. The more hydrocarbon radical in the 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.

The structure of alcohols, aldehydes,
carboxylic acids

Task 12. Make a similar table at home for the second members of the homologous series of alcohols, aldehydes and carboxylic acids.

Isomerism of alcohols, aldehydes
and carboxylic acids

1) Measurements with pyrt on the example of pentanol C 5 H 11 OH (shows the carbon chains of isomers):

Task 13. By carbon chains, name the branched isomers of alcohols with the composition C 5 H 11 OH:

Task 14. Are these substances isomers:

Task 15. What types of isomerism are typical for alcohols?

2) SIZE ME R iAl DEGIDOV on the examplen -pentanal, or valerian aldehyden-С 4 Н 9 СНО:

Task 16. What types of isomerism are characteristic of aldehydes?

3) Measurements of a carbone slot on the examplen -pentanoic, or valeric, acidn-C 4 H 9 COOH:

Task 17. What types of isomerism are characteristic of carboxylic acids?

Task 18. Write down the structural formulas of the following substances:

a) 2,4-dimethyl-3-ethylhexanal;

b) 2,2,4-trimethyl-3-isopropylpentanal;

c) 2,3,4-trimethyl-3-ethylpentanediol-1,2;

d) 2,3,4-trimethyl-3-isopropylhexanetriol-1,2,4;

e) 3,4,5,5-tetramethyl-3,4-diethylheptanoic acid;

f) 2,4-dimethylhexene-3-oic acid.

Homework

Learn the trivial names of the first five aldehydes and carboxylic acids.

Fill in the table "Structure of alcohols, aldehydes, carboxylic acids" for the second members of these homologous series (see task 12).

Write all possible isomers for butanol C 4 H 10 O, butanal C 4 H 8 O and butanoic acid C 4 H 8 O 2 , call them IUPAC.

To solve the task. One of the polyhydric alcohols is used for the preparation of antifreeze - liquids that freeze at low temperatures. Antifreezes are used in winter conditions to cool car engines. Find the molecular formula of this alcohol if the mass fraction of carbon in it is 38.7%, hydrogen - 9.7%, oxygen - 51.6%. The relative density of its vapors for hydrogen is 31. Write the structural formula of alcohol and name it.