Phenol (hydroxybenzene,carbolic acid) – Thisaboutorganicth aromatic compound with formulasohC6H5OH. Belongs to the class of the same name - phenols.

In its turn, Phenols- this is a class of organic compounds of the aromatic series, in which hydroxyl groups Oh− linked to the carbon of the aromatic ring.

According to the number of hydroxyl groups, there are:

• monohydric phenols (arenols): phenol and its homologues;
• dihydric phenols (arendiols): pyrocatechol, resorcinol, hydroquinone;
• trihydric phenols (arentriols): pyrogallol, hydroxyhydroquinone, phloroglucinol;
• polyhydric phenols.

Accordingly, actually phenol, as a substance, is the simplest representative of the phenol group and has one aromatic nucleus and one hydroxyl group IS HE.

Phenol Properties

Freshly distilled phenol is colorless needle-like crystals with a melting point 41 °С and boiling point 182 °С. When stored, especially in a humid atmosphere and in the presence of small amounts of iron and copper salts, it quickly acquires a red color. Phenol is miscible in any ratio with alcohol, water (when heated above 60 °C), freely soluble in ether, chloroform, glycerol, carbon disulfide.

Due to the presence -OH hydroxyl group, phenol has chemical properties characteristic of both alcohols and aromatic hydrocarbons.

According to the hydroxyl group, phenol enters into the following reactions:

• Since phenol has slightly stronger acidic properties than alcohols, under the influence of alkalis it forms salts - phenolates (for example, sodium phenolate - C 6 H 5 ONa):

C 6 H 5 OH + NaOH -> C 6 H 5 ONa + H 2 O

• As a result of the interaction of phenol with metallic sodium, sodium phenolate is also obtained:

2C 6 H 5 OH + 2Na -> 2C 6 H 5 ONa + H 2

• Phenol is not directly esterified with carboxylic acids; esters are obtained by reacting phenolates with anhydrides or acid halides:

C 6 H 5 OH + CH 3 COOH -> C6H 5 OCOCH 3 + NaCl

• During the distillation of phenol with zinc dust, the reaction of substitution of the hydroxyl group with hydrogen occurs:

C 6 H 5 OH + Zn -> C 6 H 6 + ZnO

Reactions of phenol on the aromatic ring:

• Phenol enters into electrophilic substitution reactions on the aromatic ring. The OH group, being one of the strongest donor groups (due to a decrease in the electron density on the functional group), increases the reactivity of the ring to these reactions and directs the substitution to ortho- and pair- provisions. Phenol is readily alkylated, acylated, halogenated, nitrated, and sulfonated.

• Kolbe-Schmitt reaction serves for the synthesis of salicylic acid and its derivatives (acetylsalicylic acid and others).

C 6 H 5 OH + CO 2 - NaOH -> C 6 H 4 OH (COONa)

C 6 H 4 OH (COONa) - H2SO4 -> C 6 H 4 OH (COOH)

Qualitative reactions to phenol:

• As a result of interaction with bromine water:

C 6 H 5 OH + 3Br 2 -> C 6 H 2 Br 3 OH + 3HBr

formed 2,4,6-tribromophenol is a white solid.

• With concentrated nitric acid:

C 6 H 5 OH + 3HNO 3 -> C 6 H 2 (NO 2) 3 OH + 3H 2 O

• With iron(III) chloride (qualitative reaction for phenol):

C 6 H 5 OH + FeCl 3 -> ⌈Fe (C 6 H 5 OH) 6 ⌉Cl 3

addition reaction

• Hydrogenation of phenol in the presence of metal catalysts Pt/Pd , Pd/Ni , get cyclohexyl alcohol:

C 6 H 5 OH -> C 6 H 11 OH

Phenol oxidation

Due to the presence of a hydroxyl group in the phenol molecule, the oxidation resistance is much lower than that of benzene. Depending on the nature of the oxidizing agent and the reaction conditions, various products are obtained.

• So, under the action of hydrogen peroxide in the presence of an iron catalyst, not a large number of diatomic phenol - pyrocatechol:

C 6 H 5 OH + 2H 2 O 2 - Fe> C 6 H 4 (OH) 2

• When interacting with stronger oxidizing agents (chromium mixture, manganese dioxide in an acidic medium), para-quinone is formed.

Getting phenol

Phenol is obtained from coal tar (coking product) and synthetically.

The coal tar of coke production contains from 0.01 to 0.1% phenols, in semi-coking products from 0.5 to 0.7%; in oil resulting from hydrogenation and in waste water taken together - from 0.8 to 3.7%. Brown coal tar and semi-coking wastewater contain from 0.1 to 0.4% phenols. Coal tar is distilled, selecting the phenolic fraction, which boils away at 160-250 °С. The composition of the phenol fraction includes phenol and its homologues (25-40%), naphthalene (25-40%) and organic bases (pyridine, quinoline). Naphthalene is separated by filtration, and the rest of the fraction is treated with 10-14% sodium hydroxide solution.

The resulting phenolates are separated from neutral oils and pyridine bases by blowing with live steam and then treated with carbon dioxide. The isolated crude phenols are subjected to rectification, selecting successively phenol, cresols and xylenols.

Most of the phenol currently produced on an industrial scale is obtained by various synthetic methods.

Synthetic methods for obtaining phenol

1. By benzenesulfonate method benzene is mixed with vitriol oil. The resulting product is treated with soda and the sodium salt of benzenesulfonic acid is obtained, after which the solution is evaporated, the precipitated sodium sulfate is separated, and the sodium salt of benzenesulfonic acid is fused with alkali. Either saturate the resulting sodium phenolate with carbon dioxide or add sulfuric acid until sulfur dioxide begins to evolve and distill off the phenol.
2. Chlorobenzene method consists in direct chlorination of benzene with gaseous chlorine in the presence of iron or its salts and saponification of the resulting chlorobenzene with a solution of sodium hydroxide or during hydrolysis in the presence of a catalyst.
3. Modified Raschig Method based on the oxidative chlorination of benzene with hydrogen chloride and air, followed by the hydrolysis of chlorobenzene and the isolation of phenol by distillation.
4. cumene method consists in the alkylation of benzene, the oxidation of the resulting isopropylbenzene to cumene hydroperoxide and its subsequent decomposition into phenol and acetone:
   Isopropylbenzene is obtained by treating benzene with pure propylene or propane-propylene fraction of oil cracking, purified from other unsaturated compounds, moisture, mercaptans and hydrogen sulfide poisoning the catalyst. Aluminum trichloride dissolved in polyalkylbenzene is used as a catalyst, for example. in diisopropylbenzene. Alkylation is carried out at 85 ° C and excess pressure 0.5 MPa, which ensures the flow of the process in the liquid phase. Isopropylbenzene is oxidized to hydroperoxide with atmospheric oxygen or technical oxygen at 110-130°C in the presence of salts of metals of variable valence (iron, nickel, cobalt, manganese) Decompose hydroperoxide with dilute acids (sulphuric or phosphoric) or small amounts of concentrated sulfuric acid at 30-60 °С. After distillation, phenol, acetone and a certain amount of α-methylstyrene. The industrial cumene method developed in the USSR is the most economically advantageous in comparison with other methods for the production of phenol. The production of phenol through benzenesulfonic acid is associated with the consumption of large amounts of chlorine and alkali. Oxidative chlorination of benzene is associated with a large consumption of steam - 3-6 times greater than when using other methods; in addition, severe corrosion of equipment occurs during chlorination, which requires the use of special materials. The cumene method is simple in hardware design and allows you to simultaneously obtain two technically valuable products: phenol and acetone.
5. During the oxidative decarboxylation of benzoic acid first, a liquid-phase catalytic oxidation of toluene to benzoic acid is carried out, which, in the presence of Сu 2+ converted to benzene salicylic acid. This process can be described by the following diagram:
   Benzoylsalicylic acid decomposes with water vapor into salicylic and benzoic acids. Phenol is formed as a result of the rapid decarboxylation of salicylic acid.

Application of phenol

Phenol is used as a raw material for the production of polymers: polycarbonate and (first bisphenol A is synthesized, and then these), phenol-formaldehyde resins, cyclohexanol (with subsequent production of nylon and nylon).

In the process of oil refining with the help of phenol, oils are purified from resinous substances, sulfur-containing compounds and polycyclic aromatic hydrocarbons.

In addition, phenol serves as a raw material for the production of ionol, neonols (), creosols, aspirin, antiseptics and pesticides.

Phenol is a good preservative and antiseptic. It is used for disinfection in animal husbandry, medicine, and cosmetology.

Toxic properties of phenol

Phenol is toxic (hazard class II). Inhalation of phenol disrupts the functions of the nervous system. Dust, vapors and phenol solution, if it comes into contact with the mucous membranes of the eyes, respiratory tract, skin, cause chemical burns. Upon contact with the skin, phenol is absorbed within a few minutes and begins to affect the central nervous system. In large doses, it can cause paralysis of the respiratory center. Lethal dose for humans if ingested 1-10 g, for kids 0.05-0.5 g.

Bibliography:
Kuznetsov EV, Prokhorova IP Album of technological schemes for the production of polymers and plastics based on them. Ed. 2nd. M., Chemistry, 1975. 74 p.
Knop A., Sheib V. Phenolic resins and materials based on them. M., Chemistry, 1983. 279 p.
Bachman A., Muller K. Phenoplasts. M., Chemistry, 1978. 288 p.
Nikolaev A.F. Technology of plastics, L., Chemistry, 1977. 366 p.

There are one-, two-, three-atomic phenols depending on the number of OH groups in the molecule (Fig. 1)

Rice. one. SINGLE-, TWO- AND TRI-ATOMIC PHENOLS

In accordance with the number of fused aromatic cycles in the molecule, there are (Fig. 2) phenols themselves (one aromatic ring - benzene derivatives), naphthols (2 fused rings - naphthalene derivatives), anthranols (3 fused rings - anthracene derivatives) and phenantrols (Fig. 2).

Rice. 2. MONO- AND POLYNUCLEAR PHENOLS

Nomenclature of alcohols.

For phenols, trivial names that have developed historically are widely used. Prefixes are also used in the names of substituted mononuclear phenols ortho-,meta- and pair -, used in the nomenclature of aromatic compounds. For more complex compounds, the atoms that are part of the aromatic cycles are numbered and the position of the substituents is indicated using digital indices (Fig. 3).

Rice. 3. NOMENCLATURE OF PHENOLS. Substituent groups and corresponding numerical indices are highlighted in different colors for clarity.

Chemical properties of phenols.

The benzene nucleus and the OH group combined in the phenol molecule affect each other, significantly increasing the reactivity of each other. The phenyl group pulls the lone electron pair away from the oxygen atom in the OH group (Fig. 4). As a result, the partial positive charge on the H atom of this group increases (indicated by the sign d+), the polarity of the O–H bond increases, which manifests itself in an increase in the acidic properties of this group. Thus, compared to alcohols, phenols are stronger acids. The partial negative charge (denoted by d–), passing to the phenyl group, is concentrated in the positions ortho- and pair-(with respect to the OH group). These reaction sites can be attacked by reagents that tend to electronegative centers, the so-called electrophilic ("electron loving") reagents.

Rice. 4. ELECTRON DENSITY DISTRIBUTION IN PHENOL

As a result, two types of transformations are possible for phenols: the substitution of a hydrogen atom in the OH group and the substitution of the H-atomobenzene nucleus. A pair of electrons of the O atom, drawn to the benzene ring, increases the strength of the C–O bond, so reactions that occur with the breaking of this bond, which are characteristic of alcohols, are not typical for phenols.

1. Substitution reactions of the hydrogen atom in the OH group. When phenols are treated with alkalis, phenolates are formed (Fig. 5A), the catalytic reaction with alcohols leads to ethers (Fig. 5B), and as a result of the reaction with anhydrides or acid chlorides of carboxylic acids, esters are formed (Fig. 5C). When interacting with ammonia (elevated temperature and pressure), the OH group is replaced by NH 2, aniline is formed (Fig. 5D), reducing reagents convert phenol to benzene (Fig. 5E)

2. Substitution reactions of hydrogen atoms in the benzene ring.

During halogenation, nitration, sulfonation and alkylation of phenol, centers with increased electron density are attacked (Fig. 4), i.e. substitution takes place mainly in ortho- and pair- positions (fig.6).

With a deeper reaction, two and three hydrogen atoms are replaced in the benzene ring.

Of particular importance are the condensation reactions of phenols with aldehydes and ketones, in essence, this is alkylation, which takes place easily and under mild conditions (at 40–50 ° C, an aqueous medium in the presence of catalysts), while the carbon atom is in the form of a methylene group CH 2 or substituted methylene group (CHR or CR 2) is inserted between two phenol molecules. Such condensation often leads to the formation of polymeric products (Fig. 7).

Dihydric phenol (trade name bisphenol A, Fig. 7) is used as a component in the production of epoxy resins. The condensation of phenol with formaldehyde underlies the production of widely used phenol-formaldehyde resins (phenolic plastics).

Methods for obtaining phenols.

Phenols are isolated from coal tar, as well as from pyrolysis products of brown coal and wood (tar). The industrial method for obtaining C 6 H 5 OH phenol itself is based on the oxidation of the aromatic hydrocarbon cumene (isopropylbenzene) with atmospheric oxygen, followed by decomposition of the resulting hydroperoxide diluted with H 2 SO 4 (Fig. 8A). The reaction proceeds with a high yield and is attractive in that it allows one to obtain two technically valuable products at once - phenol and acetone. Another method is the catalytic hydrolysis of halogenated benzenes (Fig. 8B).

Rice. eight. METHODS FOR OBTAINING PHENOL

The use of phenols.

A solution of phenol is used as a disinfectant (carbolic acid). Diatomic phenols - pyrocatechol, resorcinol (Fig. 3), as well as hydroquinone ( pair- dihydroxybenzene) is used as antiseptics (antibacterial disinfectants), introduced into tanning agents for leather and fur, as stabilizers for lubricating oils and rubber, as well as for processing photographic materials and as reagents in analytical chemistry.

In the form of individual compounds, phenols are used to a limited extent, but their various derivatives are widely used. Phenols serve as starting compounds for the production of various polymeric products, such as phenol-aldehyde resins (Fig. 7), polyamides, and polyepoxides. Based on phenols, numerous drugs are obtained, for example, aspirin, salol, phenolphthalein, in addition, dyes, perfumes, plasticizers for polymers and plant protection products.

Mikhail Levitsky

Monatomic phenols are clear liquids or crystalline substances, often pink-red in color due to their oxidation. These are poisons, and in case of contact with the skin they cause burns. They kill many microorganisms, that is, they have disinfectant and antiseptic properties. The solubility of phenols in water is low, their boiling points are relatively high due to the existence of intermolecular hydrogen bonds.

Physical properties

Phenols are sparingly soluble in water, but are readily soluble in alcohol, ether, benzene, form crystalline hydrates with water, and are distilled with water vapor. In air, phenol itself easily oxidizes and darkens. The introduction of substituents such as halides, nitro groups, etc. into the para-position of the phenol molecule significantly increases the boiling point and melting point of the compounds:

Picture 1.

Phenols are polar substances with dipole moment $\mu$ = 1.5-1.6 $D$. The $EI$ value of 8.5-8.6 eV indicates the greater donor properties of phenols compared to such arenes as benzene (9.25 eV), toluene (8.82 eV), ethylbenzene (8.76 eV). This is due to the interaction of the hydroxyl group with $\pi$-bonds of the benzene ring due to the positive $M$-effect of the $OH$-group, its negative $I$-effect prevails.

Spectral characteristics of phenols

The absorption maximum in the UV part of the spectrum for phenol is shifted towards longer wavelengths by about 15 nm compared to benzene (bathochromic shift) due to the participation of oxygen $\pi$ electrons in conjugation with the benzene nucleus and appears at 275 nm with a fine structure.

In the IR spectra for phenols, as well as for alcohols, intense $v_(OH)$ bands are characteristic in the region of 3200-3600 cm$^(-1)$ and 3600-3615 cm$^(-1)$ for highly diluted solutions , but for $v_(c\_D)$ phenols there is a band at about 1230 cm$^(-1)$ in contrast to 1220-1125 cm$^(-1)$ for alcohols.

In the PMR spectra, the proton signal of the $OH$-group of phenols manifests itself in a wide range (4.0-12.0 ppm) compared to alcohols, depending on the nature and concentration of the solvent, temperature, and the presence of inter- or intramolecular hydrogen bonds . Often, the $OH$-group proton signal is recorded at 8.5-9.5 m.h. in dimethyl sulfoxide or at 4.0-7.5 m.h, in $CCl_4$.

In the mass spectrum of phenol, the main direction of fragmentation is the elimination of $HCO$ and $CO$ particles:

Figure 2.

If alkyl radicals are present in the phenol molecule, the primary process will be benzyl cleavage.

Chemical properties of phenols

Unlike alcohols, which are characterized by reactions with splitting of both $O-H$ bonds (acid-base properties, ester formation, oxidation, etc.) and $C-O$ bonds (nucleophilic substitution reactions, dehydration, rearrangement) , phenols are more typical of reactions of the first type. In addition, they are characterized by electrophilic substitution reactions in the benzene ring activated by an electron-donating hydroxyl group.

The chemical properties of phenols are due to the mutual influence of the hydroxyl group and the benzene nucleus.

The hydroxyl group has $-I-$ and + $M$-effect. The latter significantly exceeds the $-I$ effect, which determines the $n-\pi$-conjugation of free oxygen electrons with the $\pi$-orbital of the benzene nucleus. Due to the $n-\pi$-conjugation, the $C - O$ bond length, the magnitude of the dipole moment, and the positions of the bond absorption bands in the IR spectra decrease compared to ethanol:

Some characteristics of phenol and ethanol:

Figure 3

$n-\pi$-conjugation leads to a decrease in the electron density on the oxygen atom, so the polarity of the $O - H$ bond in phenols increases. In this regard, the acidic properties of phenols are more pronounced than those of alcohols. The greater acidity of phenols compared to alcohols is also explained by the possibility of charge delocalization into the phenolate anion, which leads to the stabilization of the system:

Figure 4

The difference between the acidity of phenol and alcohols is indicated by the dissociation constant. For comparison: Kd = $1.3 \cdot 10^(-10)$ for phenol and Kd = $10^(-18)$ for ethyl alcohol.

Therefore, phenols, unlike alcohols, form phenolates not only with alkali metals, but also through interaction with alkalis:

Figure 5

The reaction of phenol with alkali metals is quite violent and may be accompanied by an explosion.

But phenol is a weak acid, even weaker than carbonic acid ($K = 4.7 \cdot 10^(-7)$). Therefore, carbonic acid displaces phenol from the phenolate solution. These reactions are used to separate phenols, alcohols or carboxylic acids. The electron-withdrawing groups in the phenol molecule significantly enhance, while the donor groups weaken the acidic properties of phenol hydroxyl.

In addition, phenol is characterized by a number of reactions of various directions:

1. the formation of ethers and esters;
2. alkylation and acylation reactions;
3. oxidation reactions

4. reactions of electrophilic substitution in the aromatic ring, including reactions:

   • halogenation,
   • sulfonation,
   • nitrosation,
   • formylation,
   • condensations with aldehydes and ketones,
   • carboxylation.

Question 2. Phenol, its structure, properties and application.

Answer. Phenols are organic compounds derived from aromatic hydrocarbons in which one or more hydroxyl groups are linked to a benzene ring.

The simplest representative of this group of substances is phenol, or carbolic acid C 6 H 5 OH. In a phenol molecule, the π-electrons of the benzene ring attract the lone pairs of electrons of the oxygen atom of the hydroxyl group, as a result of which the mobility of the hydrogen atom of this group increases.

Physical properties

Solid colorless crystalline substance, with a sharp characteristic odor, oxidizes in air during storage and acquires a pink color, poorly soluble in cold water, but readily soluble in hot water. Melting point - 43 °C, boiling point - 182 °C. Strong antiseptic, very poisonous.

Chemical properties

The chemical properties are due to the mutual influence of the hydroxyl group and the benzene ring.

Reactions on the benzene ring

1. Bromination:

C 6 H 5 OH + 3Br 2 \u003d C 6 H 2 Br 3 OH + 3HBr.

2,4,6-tribromophenol (white precipitate)

2. Interaction with nitric acid:

C 6 H 5 OH + 3HNO 3 \u003d C 6 H 2 (NO 2) 3 OH + 3H 2 O.

2,4,6-trinitrophenol (picric acid)

These reactions take place in normal conditions(without heating and catalysts), while the nitration of benzene requires temperature and catalysts.

Reactions at the hydroxy group

1. Like alcohols, it interacts with active metals:

2C 6 H 5 OH + 2Na \u003d 2C 6 H 5 ONa + H 2.

sodium phenolate

2. Unlike alcohols, it interacts with alkalis:

C 6 H 5 OH + NaOH \u003d C 6 H 5 ONa + H 2 O.

Phenolates are easily decomposed by weak acids:

a) C 6 H 5 ONa + H 2 O + CO 2 \u003d C 6 H 5 OH + NaHCO 3;

b) C 6 H 5 ONa + CH 3 I + CO 2 \u003d C 6 H 5 OCH 3 + NaI.

methylphenyl ether

3. Interaction with halogen derivatives:

C 6 H 5 OH + C 6 H 5 I \u003d C 6 H 5 OC 2 H 5 + HI

ethyl phenyl ether

4. Interaction with alcohols:

C 6 H 5 OH + HOC 2 H 5 \u003d C 6 H 5 OC 2 H 5 + H 2 O.

5. Qualitative reaction:

3C 6 H 5 OH + FeCl 3 \u003d (C 6 H 5 O) 3 Fe ↓ + 3HCl.

iron(III) phenolate

Iron(III) phenolate has a brown-violet color with an ink (ink) odor.

6. Targeting:

C 6 H 5 OH + CH 3 COOH \u003d C 6 H 5 OCOCH 3 + H 2 O.

7. Copolycondensation:

C 6 H 5 OH + CH 2 O + ... → - n. –.

methanal -H 2 O phenol-formaldehyde resin

Receipt

1. From coal tar.

2. Obtaining from chlorinated derivatives:

C 6 H 5 Cl + NaOH \u003d C 6 H 5 ONa + HCl,

2C 6 H 5 ONa + H 2 SO 4 \u003d 2C 6 H 5 OH + Na 2 SO 4.

3. Cumol method:

C 6 H 6 + CH 2 CHCH 3 C 6 H 5 CH (CH 3) 2,

C 6 H 5 CH (CH 3) 2 + O 2 С 6 H 5 C (CH 3) 2 OOH C 6 H 5 OH +CH 3 COCH 3.

phenol acetone

Application

1. As an antiseptic used as a disinfectant.

2. In the production of plastics (phenol-formaldehyde resin).

3. In the production of explosives (trinitrophenol).

4. In the production of photoreagents (developers for black and white paper).

5. In the production of medicines.

6. In the production of paints (gouache).

7. In the production of synthetic materials.

Question 3. After 200 g of a 40% KOH solution, 1.12 liters of CO 2 were passed through. Determine the type and mass of salt formed.

Answer.

Given: Find: type and mass of salt.

V (CO 2) \u003d 1.12 l.

Decision

m(KOH anhydrous)= 200*0.4=80g.

x 1 g 1.12 l x 2 g

2KOH + CO 2 \u003d K 2 CO 3 + H 2 O.

v: 2 mol 1 mol 1 mol

M: 56 g/mol - 138 g/mol

m: 112g -- 138g

x 1 \u003d m (KOH) \u003d (1.12 * 112) / 22.4 \u003d 5.6 g,

x 2 \u003d m (K 2 CO 3) \u003d 138 * 1.12 / 22.4 \u003d 6.9 g.

Since KOH is taken in excess, an average salt of K 2 CO 3 was formed, and not acidic KHCO 3.

Answer: m(K 2 CO 3) \u003d 6.9 g.

TICKET #3

Question 1.Theory of the structure of organic compounds. The value of theory for the development of science.

Answer. In 1861, the Russian scientist Alexander Mikhailovich Butlerov formulated the main provisions of the theory of the structure of organic substances.

1. Molecules of organic compounds consist of atoms interconnected in a certain sequence according to their valency (C-IV, H-I, O-II, N-III, S-II).

2. The physical and chemical properties of a substance depend not only on the nature of the atoms and their quantitative ratio in the molecule, but also on the order of the connection of the atoms, that is, on the structure of the molecule.

3. The chemical properties of a substance can be determined by knowing its molecular structure. Conversely, the structure of a molecule of a substance can be established empirically by studying the chemical transformations of a substance.

4. In molecules, there is a mutual influence of atoms or groups of atoms on each other:

CH 3 - CH 3 (t boil = 88.6 0 С), CH 3 - CH 2 - CH 3 (t boil, \u003d 42.1 0 С)

ethane propane

Based on his theory, Butlerov predicted the existence of isomers of compounds, for example, two isomers of butane (butane and isobutane):

CH 3 -CH 2 - CH 2 -CH 3 (boil t = 0.5 0 C),

CH 3 -CH (CH 3) - CH 3 (t kip \u003d -11.7 0 C).

2-methylpropane or isobutane

Isomers are substances that have the same molecular composition, but different chemical structure and therefore have different properties.

The dependence of the properties of substances on their structures is one of the ideas underlying the theory of the structure of organic substances by A.M. Butlerov.

The value of the theory of A.M. Butlerov

1. answered the main "Contradictions" of organic chemistry:

a) The variety of carbon compounds

b) apparent discrepancy between valence and organic substances:

c) different physical and chemical properties of compounds having the same molecular formula (C 6 H 12 O 6 - glucose and fructose).

2. It made it possible to predict the existence of new organic substances, and also indicate the ways to obtain them.

3. It made it possible to foresee various cases of isomerism, to predict possible directions of reactions.

Question 2. Types of chemical bonds in organic and organic compounds.

Answer: The main driving force leading to the formation of a chemical bond is the striving of atoms to complete the external energy level.

Ionic bond- a chemical bond carried out due to electrostatic attraction between ions. The formation of ionic bonds is possible only between atoms whose electronegativity values ​​are very different.

Ionic compounds include halides and oxides of alkali and alkaline earth metals (NAI, KF, CACI 2, K 2 O, LI 2 O).

Ions can also consist of several atoms, the bonds between which are not ionic:

NaOH \u003d Na + + OH -,

Na 2 SO 4 \u003d 2Na + + SO 4 2-.

It should be noted that the properties of ions differ significantly from the properties of the corresponding atoms and molecules of simple substances: Na is a metal that reacts violently with water, the Na + ion dissolves in it; H 2 - dissolves in it; H 2 - a gas without color, taste and smell, the H + ion gives the solution a sour taste, changes the color of litmus (to red).

Properties of ionic compounds

1. Ionic compounds are electrolytes. Electric current is conducted only by solutions and melts.

2. Great fragility of crystalline substances.

covalent bond- a chemical bond carried out by the formation of common (bonding) electron pairs.

Covalent non-polar bond- A bond formed between atoms that have the same electronegativity. With a covalent non-polar bond, the electron density of a common pair of electrons is distributed in space symmetrically with respect to the nuclei of common atoms (H 2, I 2, O 2, N 2).

Covalent polar bond - a covalent bond between atoms with different (but not very different from each other) electronegativity (H 2 S, H 2 O, NH 3).

According to the donor-acceptor mechanism, NH + 4, H 3, O +, SO 3, NO 2 are formed. In the case of the appearance of the NH + 4 ion, the nitrogen atom is a donor, providing for common use an unshared electron pair, and a hydrogen ion is an acceptor, accepting this pair and providing its own orbital for this. In this case, a donor-acceptor (coordination) bond is formed. The acceptor atom acquires a large negative charge, and the donor atom acquires a positive one.

Compounds with a covalent polar bond have higher boiling and melting points than substances with a covalent non-polar bond.

In the molecules of organic compounds, the bond of atoms is covalent polar.

In such molecules, hybridization occurs (mixing of orbitals and aligning them according to the formula and energy) of the valence (external) orbitals of carbon atoms.

Hybrid orbitals overlap and strong chemical bonds are formed.

Metal ties- a bond carried out by relatively free electrons between metal ions in a crystal lattice. Metal atoms easily donate electrons, turning into positively charged ions. The detached electrons move freely between the positive metal ions, i.e. they are socialized by metal ions, i.e. they are socialized and move around the whole piece of metal, which is generally electrically neutral.

Properties of metals.

1. Electrical conductivity. It is due to the presence of free electrons capable of creating an electric current.

2. Thermal conductivity. Due to the same.

3. Malleability and plasticity. Metal ions and atoms in a metal lattice are not directly connected to each other, and individual metal layers can move freely relative to each other.

Hydrogen bond- can be intermolecular and intramolecular.

Intermolecular hydrogen bond is formed between the hydrogen atoms of one molecule and the atoms of a strongly electronegative element (F, O, N) of another molecule. This connection determines the abnormally high boiling and melting points of some compounds (HF, H 2 O). During the evaporation of these substances, hydrogen bonds are broken, which requires the expenditure of additional energy.

The reason for the hydrogen bond: when a single electron is donated to its “own” atom of an electronegative element, hydrogen acquires a relatively strong positive charge, which then interacts with an unshared electron pair of a “foreign” atom of an electronegative element.

Intramolecular hydrogen bond takes place within the molecule. This bond determines the structure of nucleic acids (double helix) and the secondary (helical) structure of the protein.

The hydrogen bond is much weaker than the ionic or covalent bond, but stronger than the intermolecular interaction.

Question 3. Solve a problem. 20 g of nitrobenzene was subjected to a reduction reaction. Find the mass of aniline formed if the reaction yield is 50%.

Answer.

Given: Find: m(C 6 H 6 NH 2).

m (C 6 H 6 NO 2) \u003d 20 g,

Decision

(C 6 H 6 NO 2) + 3H 2 = C 6 H 6 NH 2 + 2H 2 0.

v: 1 mol 1 mol

M: 123g/mol 93g/mol

x \u003d m theor (C 6 H 6 NH 2) \u003d 20 * 93 / 123 \u003d 15g,

m practical \u003d 15 * 0.5 \u003d 7.5 g.

Answer: 7.5 g

Ticket number 4

Properties Metal	Li, K, Rb, Ba, Sr, Ca, Na, Mg, Al, Mn, Zn, Cr, Fe, Ni, Sn, Pb, (H), Cu, Hg, Ag, Pt, Au
Restorability (donate electrons)	Increasing
Interaction with atmospheric oxygen	Oxidizes quickly at normal temperatures	Slowly oxidized at normal temperature or when heated	Do not oxidize
Interaction with water	H 2 is released and hydroxide is formed	When heated, hydrogen is released and hydroxide is formed	Does not displace hydrogen from water
Interaction with acids	Displaces hydrogen from dilute acids	Will not displace hydrogen from dilute acids
Oxidizing ability (attach electrons)	Increasing

Question 1. General properties of metals. Features of the structure of atoms .

Answer. Metal atoms donate valence electrons relatively easily and are converted into positively charged ions. Therefore, metals are reducing agents. This is the main and most general chemical property of metals. Metal compounds exhibit only positive oxidation states. The reducing ability of different metals is not the same and increases in the electrochemical series of metal voltages from Au to Li.

Physical properties

1. Electrical conductivity. It is due to the presence of free electrons in metals, which form an electric current (directed movement of electrons).

2. Thermal conductivity.

3. Malleability and plasticity.

Metals with ρ<5 г /см 3 – легкие, c ρ >5 g / cm 3 - heavy.

Low-melting metals: c t pl< 1000 0 C ,тугоплавкие – c t пл >10000C.

Schemes of interaction of metals with sulfuric acid.

Dilute H 2 SO 4 dissolves metals located in a series of standard electrode potentials (metal activity series) to hydrogen:

M + H 2 SO 4 (dec.) → salt + H 2

(M = (Li → Fe) in the metal activity series).

In this case, the corresponding salt and water are formed.

With Ni, dilute H 2 SO 4 reacts very slowly; with Ca, Mn, and Pb, the acid does not react. Under the action of acid, a PbSO 4 film is formed on the lead surface, protecting it from further interaction with the acid.

concentrated H 2 SO 4 at ordinary temperature does not interact with many metals. However, when heated, concentrated acid reacts with almost all metals (except Pt, Au and some others). In this case, the acid is reduced to H 2 S, or SO 2:

M + H 2 SO 4 (conc.) → salt + H 2 O + H 2 S (S, SO 2).

Hydrogen is not released in these reactions, but water is formed.

Schemes of interaction of metals with nitric acid.

When metals interact with HNO 3, hydrogen is not released; it oxidizes to form water. Depending on the activity of the metal, the acid can be reduced to compounds.

5 +4 +2 +1 0 -3 -3

HNO 3 → NO 2 → NO → N 2 O → N 2 → NH 3 (NH 4 NO 3).

In this case, a salt of nitric acid is also formed.

Diluted HNO 3 reacts with many metals (exception: Ca, Cr, Pb, Au) most often with the formation of NH 3, NH 4 NO 3, N 2 or NO:

M + HNO 3 (razb.) → salt + H 2 O + NH 3 (NH 4 NO 3, N 2, NO).

concentrated HNO 3 interacts mainly with heavy metals to form N 2 O or NO 2:

M + HNO 3 (conc.) → salt + H 2 O + N 2 O (NO 2).

At ordinary temperature, this acid (a strong oxidizing agent) does not react with Al, Cr, Fe and Ni. It easily converts them into a passive state (a dense protective oxide film is formed on the metal surface, which prevents the metal from contacting the medium.)

Question 2. starch and cellulose. Compare their structure and properties. Their application.

Answer. The structure of starch: structural link - the rest of the molecule

α-glucose. The structure of cellulose: a structural unit-residue of the β-glucose molecule.

Physical properties

Starch is a white, crisp powder that is insoluble in cold water. In hot water forms a colloidal solution-paste.

Cellulose is a hard fibrous substance that is insoluble in water and organic solvents.

Chemical properties

1. Starch cellulose undergoes hydrolysis:

(C 6 H 10 O 5) n + nH 2 O \u003d nC 6 H 12 O 6.

The hydrolysis of starch produces alpha-glucose, while the hydrolysis of cellulose produces beta-glucose.

2. Starch with iodine gives a blue color (unlike cellulose).

3. Starch is digested in the human digestive system, but cellulose is not digested.

4. Cellulose is characterized by the esterification reaction:

[(C 6 H 7 O 2) (OH) 3 ] n + 3nHONO 2 (conc.) [(C 6 H 7 O 2) (ONO 2) 3 ] n + 3nH 2 O.

trinitrocellulose

5. Starch molecules have both linear and branched structures. Cellulose molecules, on the other hand, have a linear (that is, not branched) structure, due to which cellulose easily forms fibers. This is the main difference between starch and cellulose.

6. Combustion of starch and cellulose:

(C 6 H 10 O 5) n + O 2 \u003d CO 2 + H 2 O + Q.

Without access to air, thermal decomposition occurs. CH 3 O, CH 3 COOH, (CH 3) 2 CO, etc. are formed.

Application

1. By hydrolysis, they are converted into flow and glucose.

2. As a valuable and nutritious product (the main carbohydrate of human food is bread, cereals, potatoes).

3. In the production of paste.

4. In the production of paints (thickener)

5. In medicine (for the preparation of ointments, powders).

6. For starching linen.

Cellulose:

1. In the production of acetate fiber, plexiglass, flame retardant film (cellophane).

2. In the manufacture of smokeless powder (trinitrocellulose).

3. In the production of celluloid and kolodite (dinitrocellulose).

Question 3. To 500 grams of a 10% solution of NACL was added 200 grams of a 5% solution of the same substance, then another 700 grams of water. Find the percentage concentration of the resulting solution.

Answer. Find:m 1 (NaCl) \u003d 500g

Given:

ω 1 (NaCl) \u003d 10%

m 2 (NaCl) \u003d 200g

Decision

m 1 (NaCl, anhydrous) \u003d 500 * 10\100 \u003d 50 g,

m 2 (NaCl, anhydrous) \u003d 200 * 5 \ 100 \u003d 10 g,

m (r-ra) \u003d 500 + 200 + 700 \u003d 1400g,

m total (NaCl)=50+10=60g,

ω 3 (NaCl) \u003d 60 \ 1400 * 100% \u003d 4.3%

Answer: ω 3 (NaCl) \u003d 4.3%

TICKET #5

Question 1. Acetylene. Its structure, properties, preparation and application.

Answer. Acetylene belongs to the class of alkynes.

Acetelene hydrocarbons, or alkynes, are unsaturated (unsaturated) hydrocarbons with the general formula , in the molecules of which there is a triple bond between carbon atoms.

Electronic structure

The carbon in the acetylene molecule is in the state sp- hybridization. The carbon atoms in this molecule form a triple bond, consisting of two -bonds and one σ-bond.

Molecular formula: .

Graphic formula: H-C≡ C-H

Physical properties

Gas, lighter than air, slightly soluble in water, in its pure form, almost odorless, colorless, = - 83.6. (In the alkyne series, as the molecular weight of the alkyne increases, the boiling and melting points increase.)

Chemical properties

1. Combustion:

2. Connection:

a) hydrogen:

b) halogen:

C 2 H 2 + 2Cl 2 \u003d C 2 H 2 Cl 4;

1,1,2,2-tetrochloroethane

c) hydrogen halide:

HC≡CH + HCl = CHCl

vinyl chloride

CH 2 \u003d CHCl + HCl \u003d CH 3 -CHCl 2

1,1-dichloroethane

(according to Markovnikov's rule);

d) water (Kucherov reaction):

HC \u003d CH + H 2 O \u003d CH 2 \u003d CH-OH CH 3 -CHO

vinyl alcohol acetaldehyde

3. Substitution:

HC≡CH + 2AgNO 3 + 2NH 4 = AgC≡CAg↓+ 2NH 4 NO 3 + 2H 2 O.

silver acetylenide

4. Oxidation:

HC≡CH + + H 2 O → HOOC-COOH (-KMnO 4).

oxalic acid

5. Trimerization:

3HC≡CH t, cat

6. Dimerization:

HC≡CH + HC≡CH CAT. HC≡C - HC=CH 2

vinylacetylene

Receipt

1. Dehydrogenation of alkanes (cracking of liquid petroleum fractions):

C 2 H 6 \u003d C 2 H 2 + 2H 2.

2. From natural gas (thermal cracking of methane):

2CH 4 C 2 H 2 + 3H 2

3. Carbide way:

CaC 2 + 2H 2 O \u003d Ca (OH) 2 + C 2 H 2

Application

1. In the production of vinyl chloride, acetaldehyde, vinyl acetate, chloroprene, acetic acid and other organic substances.

2. In the synthesis of rubber and polyvinyl chloride resins.

3. In the production of polyvinyl chloride (leatherette).

4. In the production of varnishes, medicines.

5. In the manufacture of explosives (acetylides).

The figure shows the relationship of various methods for the production of phenol, and in the table under the same numbers their technical and economic indicators are given (in% relative to the sulfonate method).

Rice. 1.1. Phenol Production Methods

Table 1.3

Technical and economic indicators of phenol production

	Methods
Indicator	1	2	3	4	5	6
Capital expenditures	100	83	240	202	208	202
Raw material cost	100	105	58	69	72	45
Cost price	100	96	70	73	76	56

Thus, from an economic point of view, the cumene process that is most in demand at the present time is the most expedient. The industrial processes that have been used at one time or another to produce phenol are briefly described below.

1. Sulfonate process was the first phenolic process implemented on an industrial scale by BASF in 1899. This method is based on the sulfonation of benzene with sulfuric acid, followed by alkaline melting of the sulfonic acid. Despite the use of aggressive reagents and the generation of a large amount of sodium sulfite waste, this method has been used for almost 80 years. In the USA, this production was closed only in 1978.

2. In 1924, the Dow Chemical company developed a process for producing phenol, including the reaction of benzene chlorination and subsequent hydrolysis of monochlorobenzene ( catalytic hydrolysis process of halogenated benzenes ). An independently similar technology was developed by the German firm I.G. Farbenindustrie Co. Subsequently, the stage for obtaining monochlorobenzene and the stage for its hydrolysis were improved, and the process was called the "Raschig process". The total yield of phenol in two stages is 70-85%. This process has been the main method for producing phenol for several decades.

3. Cyclohexane process , developed by Scientific Design Co., is based on the oxidation of cyclohexane to a mixture of cyclohexanone and cyclohexanol, which is then dehydrogenated to form phenol. In the 1960s, Monsanto used this method for several years at one of its plants in Australia, but later switched it to the cumene method for producing phenol.

4. In 1961, Dow Chemical of Canada sold process through decomposition of benzoic acid , this is the only method for the synthesis of phenol based on the use of non-benzene raw materials. Both reactions proceed in the liquid phase. First reaction. toluene oxidation. was used in Germany already during World War II to produce benzoic acid. The reaction proceeds under rather mild conditions with a high yield. The second step is more difficult due to catalyst deactivation and low phenol selectivity. It is believed that carrying out this step in the gas phase can make the process more efficient. Currently, this method is used in practice, although its share in the world production of phenol is only about 5%.

5. The synthesis method by which today most of the phenol produced in the world is obtained - cumene process - opened by a group of Soviet chemists headed by Professor P. G. Sergeev in 1942. The method is based on the oxidation of the aromatic hydrocarbon cumene (isopropylbenzene) with atmospheric oxygen, followed by the decomposition of the resulting hydroperoxide diluted with sulfuric acid. In 1949, the world's first cumene plant was put into operation in the city of Dzerzhinsk, Gorky Region. Prior to this, hydroperoxides were considered to be unstable intermediate products of hydrocarbon oxidation. Even in laboratory practice, they were almost never used. In the West, the cumene method was developed in the late 1940s and is partly known as the Hock process, after a German scientist who later independently discovered the cumene route for the synthesis of phenol. On an industrial scale, this method was first used in the United States in the early 1950s. Since that time, for many decades, the cumene process has become a model of chemical technology throughout the world.

Despite the well-established technology and long operating experience, the cumene method has a number of disadvantages. First of all, this is the presence of an explosive intermediate compound (cumene hydroperoxide), as well as the multi-stage method, which requires increased capital costs and makes it difficult to achieve a high yield of phenol based on the initial benzene. So, with a useful product yield of 95% at each of the three stages, the final yield will be only 86%. Approximately this yield of phenol gives the cumene method at the present time. But the most important and fundamentally unremovable drawback of the cumene method is related to the fact that acetone is formed as a by-product. This circumstance, which was originally seen as a strength of the method, is becoming a more and more serious problem, since acetone does not find an equivalent market. In the 1990s, this problem became especially noticeable after the creation of new methods for the synthesis of methyl methacrylate by the oxidation of C4 hydrocarbons, which drastically reduced the need for acetone. The acuteness of the situation is evidenced by the fact that a technology has been developed in Japan that provides for the recycling of acetone. To this end, two more stages are added to the traditional cumene scheme, the hydrogenation of acetone to isopropyl alcohol and the dehydration of the latter to propylene. The resulting propylene is again returned to the benzene alkylation step. In 1992, Mitsui launched a large-scale production of phenol (200,000 tons/year) based on this five-stage cumene technology.

Rice. 1.2. Acetone recycling to propylene

Other similar modifications to the cumene method are also proposed that would mitigate the acetone problem. However, all of them lead to a significant complication of the technology and cannot be considered as a promising solution to the problem. Therefore, research focused on the search for new routes for the synthesis of phenol, which would be based on the direct oxidation of benzene, has acquired a particularly intensive character in the last decade. Work is carried out mainly in the following areas: oxidation with molecular oxygen, oxidation with monatomic oxygen donors and conjugated oxidation. Let us consider in more detail the directions of the search for new ways of synthesis of phenol.