Phenol: what the substance is, its effect on the human body. Using phenol for disinfection

Hydroxybenzene

Chemical properties

What is Phenol? Hydroxybenzene, what is it? According to Wikipedia, this is one of the simplest representatives of its class of aromatic compounds. Phenols are organic aromatic compounds in whose molecules carbon atoms from the aromatic ring are attached to the hydroxyl group. General formula of phenols: C6H6n(OH)n. According to the standard nomenclature, organic substances of this series are distinguished by the number of aromatic nuclei and HE- groups. There are monoatomic arenoles and homologues, diatomic arenediols, terchatom arenetriols and polyatomic formulas. Phenols also tend to have a number of spatial isomers. For example, 1,2-dihydroxybenzene (pyrocatechin ), 1,4-dihydroxybenzene (hydroquinone ) are isomers.

Alcohols and phenols differ from each other by the presence of an aromatic ring. Ethanol is a homologue of methanol. Unlike Phenol, methanol interacts with aldehydes and enters into esterification reactions. The statement that methanol and phenol are homologues is incorrect.

If we consider in detail the structural formula of Phenol, we can note that the molecule is a dipole. In this case, the benzene ring is the negative end, and the group HE– positive. The presence of a hydroxyl group causes an increase in electron density in the ring. The lone pair of electrons of oxygen enters into conjugation with the pi-system of the ring, and the oxygen atom is characterized by sp2 hybridization. Atoms and atomic groups in a molecule have a strong mutual influence on each other, and this is reflected in the physical and chemical properties of substances.

Physical properties. The chemical compound has the form of colorless needle-shaped crystals that turn pink in air because they are susceptible to oxidation. The substance has a specific chemical odor, it is moderately soluble in water, alcohols, alkali, acetone and benzene. Molar mass = 94.1 grams per mole. Density = 1.07 g per liter. Crystals melt at 40-41 degrees Celsius.

What does Phenol interact with? Chemical properties of Phenol. Due to the fact that the molecule of the compound contains both an aromatic ring and a hydroxyl group, it exhibits some properties of alcohols and aromatic hydrocarbons.

How does the group react? HE? The substance does not exhibit strong acidic properties. But it is a more active oxidizing agent than alcohols; unlike ethanol, it interacts with alkalis to form phenolate salts. Reaction with sodium hydroxide :C6H5OH + NaOH → C6H5ONa + H2O. The substance reacts with sodium (metal): 2C6H5OH + 2Na → 2C6H5ONa + H2.

Phenol does not react with carboxylic acids. Esters are obtained by reacting phenolate salts with acid halides or acid anhydrides. The reaction of formation of ethers is not typical for the chemical compound. Esters form phenolates when exposed to haloalkanes or halogenated arenes. Hydroxybenzene reacts with zinc dust, and the hydroxyl group is replaced by N, the reaction equation is as follows: C6H5OH + Zn → C6H6 + ZnO.

Chemical interaction on the aromatic ring. The substance is characterized by reactions of electrophilic substitution, alkylation, halogenation, acylation, nitration and sulfonation. Of particular importance are the reactions of salicylic acid synthesis: C6H5OH + CO2 → C6H4OH(COONa), occurs in the presence of a catalyst sodium hydroxide . Then upon exposure it is formed.

Reaction of interaction with bromine water is a qualitative reaction to Phenol. C6H5OH + 3Br2 → C6H2Br2OH + 3HBr. Bromination produces a white solid - 2,4,6-tribromophenol . Another qualitative reaction - with ferric chloride 3 . The reaction equation is as follows: 6C6H5OH + FeCl3 → (Fe(C6H5OH)6)Cl3.

Phenol nitration reaction: C6H5OH + 3HNO3 → C6H2(NO2)3OH + 3 H2O. The substance is also characterized by an addition reaction (hydrogenation) in the presence of metal catalysts, platinum, aluminum oxide, chromium, and so on. As a result, cyclohexanol And cyclohexanone .

A chemical compound undergoes oxidation. The stability of the substance is significantly lower than that of benzene. Depending on the reaction conditions and the nature of the oxidizing agent, different reaction products are formed. Under the influence of hydrogen peroxide in the presence of iron, diatomic phenol is formed; upon action manganese dioxide , chromium mixture in an acidified environment – ​​para-quinone.

Phenol reacts with oxygen, combustion reaction: C6H5OH +7O2 → 6CO2 + 3H2O. Also of particular importance for industry is the polycondensation reaction with formaldehyde (For example, metanalem ). The substance enters into a polycondensation reaction until one of the reactants is completely consumed and huge macromolecules are formed. As a result, solid polymers are formed, phenol-formaldehyde or formaldehyde resins . Phenol does not interact with methane.

Receipt. At the moment, several methods for the synthesis of hydroxybenzene exist and are actively used. The cumene method for producing phenol is the most common of them. About 95% of the total production volume of the substance is synthesized in this way. In this case, it undergoes non-catalytic oxidation with air. cumene and is formed cumene hydroperoxide . The resulting compound decomposes when exposed to sulfuric acid on acetone and Phenol. An additional by-product of the reaction is alpha methylstyrene .

The compound can also be obtained by oxidation toluene , the intermediate product of the reaction will be benzoic acid . Thus, about 5% of the substance is synthesized. All other raw materials for various needs are isolated from coal tar.

How to obtain from benzene? Phenol can be obtained using the direct oxidation reaction of benzene NO2() with further acid decomposition sec-butylbenzene hydroperoxide . How to obtain phenol from chlorobenzene? There are two options for obtaining from chlorobenzene of this chemical compound. The first is the reaction of interaction with an alkali, for example, with sodium hydroxide . As a result, phenol and table salt are formed. The second is a reaction with water vapor. The reaction equation is as follows: C6H5-Cl + H2O → C6H5-OH + HCl.

Receipt benzene from Phenol. To do this, you first need to treat benzene with chlorine (in the presence of a catalyst), and then add an alkali to the resulting compound (for example, NaOH). As a result, phenol is formed.

Transformation methane - acetylene - benzene - chlorobenzene can be done as follows. First, the methane decomposition reaction is carried out at a high temperature of 1500 degrees Celsius until acetylene (С2Н2) and hydrogen. Then acetylene under special conditions and high temperature is converted into benzene . Chlorine is added to benzene in the presence of a catalyst FeCl3, obtain chlorobenzene and hydrochloric acid: C6H6 + Cl2 → C6H5Cl + HCl.

One of the structural derivatives of phenol is an amino acid, which has important biological significance. This amino acid can be considered as a para-substituted phenol or alpha-substituted para-cresol . Cresols – quite common in nature along with polyphenols. Also, the free form of the substance can be found in some microorganisms in equilibrium with tyrosine .

Hydroxybenzene is used:

• in production bisphenol A , epoxy resin and polycarbonate ;
• for the synthesis of phenol-formaldehyde resins, nylon, nylon;
• in the oil refining industry, for the selective purification of oils from aromatic sulfur compounds and resins;
• in the production of antioxidants, surfactants, cresols , lek. drugs, pesticides and antiseptics;
• in medicine as an antiseptic and analgesic for local use;
• as a preservative in the manufacture of vaccines and smoked food products, in cosmetology during deep peeling;
• for disinfection of animals in cattle breeding.

Hazard Class. Phenol is an extremely toxic, poisonous, caustic substance. When a volatile compound is inhaled, the functioning of the central nervous system is disrupted; the vapors irritate the mucous membranes of the eyes, skin, and respiratory tract and cause severe chemical burns. When it comes into contact with the skin, the substance is quickly absorbed into the bloodstream and reaches the brain tissue, causing paralysis of the respiratory center. The lethal dose when taken orally for an adult ranges from 1 to 10 grams.

pharmachologic effect

Antiseptic, cauterizing.

Pharmacodynamics and pharmacokinetics

The product exhibits bactericidal activity against aerobic bacteria, their vegetative forms and fungi. Has virtually no effect on fungal spores. The substance interacts with the protein molecules of microbes and leads to their denaturation. Thus, the colloidal state of the cell is disrupted, its permeability increases significantly, and redox reactions are disrupted.

In aqueous solution it is an excellent disinfectant. When using a 1.25% solution, practically microorganisms die within 5-10 minutes. Phenol, in a certain concentration, has a cauterizing and irritating effect on the mucous membrane. The bactericidal effect of using the product increases with increasing temperature and acidity.

When it comes into contact with the surface of the skin, even if it is not damaged, the medicine is quickly absorbed and penetrates the systemic bloodstream. Upon systemic absorption of the substance, its toxic effect is observed, mainly on the central nervous system and the respiratory center in the brain. About 20% of the dose taken is subject to oxidation; the substance and its metabolic products are excreted through the kidneys.

Indications for use

Application of Phenol:

• for disinfection of instruments and linen and disinsection;
• as a preservative in some medications. products, vaccines, suppositories and serums;
• for superficial pyoderma , folliculitis , conflictene , ostiofolliculitis , sycosis , streptococcal impetigo ;
• for the treatment of inflammatory diseases of the middle ear, oral cavity and pharynx, periodontitis , genital pointed condylomas .

Contraindications

The substance is not used:

• with widespread lesions of the mucous membrane or skin;
• for the treatment of children;
• during breastfeeding and;
• at Phenol.

Side effects

Sometimes the drug can provoke the development of allergic reactions, itching, irritation at the site of application and a burning sensation.

Instructions for use (Method and dosage)

Preservation of drugs, serums and vaccines is carried out using 0.5% Phenol solutions.

For external use, the medicine is used in the form of an ointment. The drug is applied in a thin layer to the affected areas of the skin several times a day.

For treatment, the substance is used in the form of a 5% solution in. The drug is heated and 10 drops are instilled into the affected ear for 10 minutes. Then you need to remove the remaining medication using cotton wool. The procedure is repeated 2 times a day for 4 days.

Phenol preparations for the treatment of ENT diseases are used in accordance with the recommendations in the instructions. The duration of therapy is no more than 5 days.

To eliminate spiky condylomas they are treated with a 60% Phenol solution or a 40% solution tricresol . The procedure is carried out once every 7 days.

When disinfecting linen, use 1-2% soap-based solutions. Using a soap-phenolic solution, treat the room. Phenolic-turpentine and kerosene mixtures are used for disinsection.

Overdose

When the substance gets on the skin, a burning sensation, redness of the skin, and anesthesia of the affected area occur. The surface is treated with vegetable oil or polyethylene glycol . Symptomatic therapy is carried out.

Symptoms of Phenol poisoning if ingested. There is severe pain in the abdomen, pharynx, and mouth, the victim vomits a brown mass, pale skin, general weakness and dizziness

The product should not be used on large areas of skin.

Before using the substance to disinfect household items, they must be mechanically cleaned, since the product is absorbed by organic compounds. After treatment, things can retain a specific odor for a long time.

The chemical compound cannot be used to treat premises for storing and preparing food products. It does not affect the color or structure of the fabric. Damages varnished surfaces.

For children

The product cannot be used in pediatric practice.

During pregnancy and lactation

Phenol is not prescribed during breastfeeding and during pregnancy .

Drugs containing (Analogs)

Level 4 ATX code matches:

Phenol is included in the following drugs: Feresol , Phenol solution in glycerin , Pharmaseptic . Contained in the preparations as a preservative: Belladonna extract , Skin diagnostic kit for drug allergies , and so on.

Phenol is an organic chemical substance, a hydrocarbon. Other names: carbolic acid, hydroxybenzene. It comes in natural and industrial origin. What is phenol and what is its significance in human life?

Origin of the substance, chemical and physical properties

The chemical formula of phenol is c6h5oh. In appearance, the substance resembles crystals in the form of needles, transparent, with a white tint. In the open air, when exposed to oxygen, the color becomes light pink. The substance has a specific odor. Phenol smells like gouache paint.

Natural phenols are antioxidants that are present in varying amounts in all plants. They determine color, aroma, and protect plants from harmful insects. Natural phenol is beneficial for the human body. It is found in olive oil, cocoa beans, fruits, and nuts. But there are also toxic compounds, such as tannin.

The chemical industry produces these substances through synthesis. They are poisonous and very toxic. Phenol is dangerous for humans, and the industrial scale of its production significantly pollutes the environment.

Physical properties:

• Phenol dissolves normally in water, alcohol, alkali;
• has a low melting point, at 40°C it turns into gas;
• its properties are in many ways similar to alcohol;
• has high acidity and solubility;
• at room temperature they are in a solid state;
• The smell of phenol is pungent.

How are phenols used?

More than 40% of the substances are used in the chemical industry to produce other organic compounds, mainly resins. It is also made from artificial fibers - nylon, nylon. The substance is used in the oil refining industry to purify oils that are used in drilling rigs and other technological facilities.

Phenol is used in the production of paints and varnishes, plastics, and in chemicals and pesticides. In veterinary medicine, farm animals are treated with the substance to prevent infections.

The use of phenol in the pharmaceutical industry is significant. It is included in many medications:

• antiseptics;
• painkillers;
• antiplatelet agents (thin the blood);
• as a preservative for vaccine production;
• in cosmetology as part of preparations for chemical peeling.

In genetic engineering, phenol is used to purify DNA and extract it from cells.

Toxic effect of phenol

Phenol is poison. In terms of its toxicity, the compound belongs to hazard class 2. This means that it is highly hazardous to the environment. The degree of impact on living organisms is high. The substance can cause serious damage to the ecological system. The minimum recovery period after the action of phenol is at least 30 years, provided that the source of pollution is completely eliminated.

Synthetic phenol has a negative effect on the human body. Toxic effect of the compound on organs and systems:

1. If vapors are inhaled or swallowed, the mucous membranes of the digestive tract, upper respiratory tract, and eyes are affected.
2. If it comes into contact with the skin, a phenol burn will form.
3. With deep penetration it causes tissue necrosis.
4. Has a pronounced toxic effect on internal organs. When the kidneys are damaged, it causes pyelonephritis, destroys the structure of red blood cells, which leads to oxygen starvation. Can cause allergic dermatitis.
5. When phenol is inhaled in high concentrations, brain activity is disrupted and can lead to respiratory arrest.

The mechanism of the toxic effect of phenols is a change in the structure of the cell and, as a consequence, its functioning. Neurons (nerve cells) are the most susceptible to toxic substances.

Maximum permissible concentration (MPC of phenol):

• the maximum single dose in the atmosphere for populated areas is 0.01 mg/m³, which remains in the air for half an hour;
• the average daily dose in the atmosphere for populated areas is 0.003 mg/m³;
• the lethal dose when ingested is for adults from 1 to 10 g, for children from 0.05 to 0.5 g.

Symptoms of phenol poisoning

The harm of phenol to living organisms has long been proven. When it comes into contact with the skin or mucous membranes, the compound is quickly absorbed, overcomes the hematogenous barrier and spreads through the blood throughout the body.

The brain is the first to respond to the effects of poison. Signs of poisoning in humans:

• Psyche. Initially, the patient experiences mild excitement, which does not last long and is replaced by irritation. Then comes apathy, indifference to what is happening around, the person is in a depressed state.
• Nervous system. General weakness, lethargy, loss of strength increases. Tactile sensitivity is blurred, but the reaction to light and sounds is exacerbated. The victim feels nausea, which is not related to the functioning of the digestive system. Dizziness appears and the headache becomes more intense. Severe poisoning can lead to convulsions and unconsciousness.
• Skin. The skin becomes pale and cold to the touch, and in severe cases acquires a blue tint.
• Respiratory system. If even small doses enter the body, a person may experience shortness of breath and rapid breathing. Due to irritation of the nasal mucosa, the victim is continuously sneezing. In case of moderate poisoning, a cough and spastic contractions of the larynx develop. In severe cases, the threat of spasm of the trachea and bronchi increases and, as a result, suffocation, leading to death.

Circumstances under which poisoning can occur are violation of safety rules when working with particularly dangerous substances, overdose of medications, household poisoning with detergents and cleaning products, as a result of an accident.

If the house contains low-quality furniture, children's toys that do not meet international safety standards, or the walls are painted with paint that is not intended for these purposes, then the person constantly inhales the emanating phenol vapors. In this case, chronic poisoning develops. Its main symptom is chronic fatigue syndrome.

Principles of first aid

The first thing to do is to interrupt human contact with the poisonous source.

Take the victim out of the room into fresh air, unfasten buttons, locks, and zippers to better ensure access to oxygen.

If the phenol solution gets on your clothing, remove it immediately. Rinse the affected skin and mucous membranes of the eyes thoroughly and repeatedly with running water.

If phenol gets into your mouth, do not swallow anything, but immediately rinse your mouth for 10 minutes. If the substance has managed to enter the stomach, you can drink the sorbent with a glass of water:

• activated or white carbon;
• enterosorb;
• enterosgel;
• sorbex;
• carbolene;
• polysorb;
• lactofiltrum.

You should not rinse the stomach, as this procedure will increase the severity of the burn and increase the area of ​​damage to the mucous membrane.

Phenol antidote is a solution of calcium gluconate for intravenous administration. In case of poisoning of any severity, the victim is taken to the hospital for observation and treatment.

In case of severe poisoning, phenol can be removed from the body in a hospital setting using the following methods:

1. Hemosorption is the purification of blood with a special sorbent that binds molecules of a toxic substance. The blood is purified by passing through a special apparatus.
2. Detoxification therapy is the intravenous infusion of solutions that dilute the concentration of a substance in the blood and promote its natural elimination from the body (through the kidneys).
3. Hemodialysis is indicated in severe cases where there is a potential threat to life. The procedure is carried out using an “artificial kidney” apparatus, in which the blood passes through special membranes and leaves molecules of a toxic substance. Blood returns to the body clean and saturated with useful microelements.

Phenol is a synthetic toxic substance that is dangerous to humans. Even a naturally occurring compound can be harmful to health. To avoid poisoning, it is necessary to responsibly work in production where there is a risk of contact with poison. When shopping, be interested in the composition of the products. The unpleasant smell of plastic products should alert you. When using medications containing phenol, follow the prescribed dosage.

Phenols- derivatives of aromatic hydrocarbons, which may contain one or more hydroxyl groups connected to a benzene ring.

What are phenols called?

According to IUPAC rules, the name " phenol" The numbering of atoms comes from the atom that is directly bonded to the hydroxy group (if it is the senior one) and is numbered so that the substituents receive the lowest number.

Representative - phenol - C 6 H 5 OH:

The structure of phenol.

The oxygen atom has a lone electron pair at its outer level, which is “pulled” into the ring system (+M effect HE-groups). As a result, 2 effects can occur:

1) increasing the electron density of the benzene ring to the ortho- and para- positions. Basically, this effect manifests itself in electrophilic substitution reactions.

2) the density on the oxygen atom decreases, as a result of which the bond HE weakens and may tear. The effect is associated with the increased acidity of phenol compared to saturated alcohols.

Mono-substituted derivatives phenol(cresol) can be in 3 structural isomers:

Physical properties of phenols.

Phenols are crystalline substances at room temperature. Poorly soluble in cold water, but well soluble in hot water and in aqueous solutions of alkalis. They have a characteristic odor. Due to the formation of hydrogen bonds, they have a high boiling and melting point.

Preparation of phenols.

1. From halobenzenes. When chlorobenzene and sodium hydroxide are heated under pressure, sodium phenolate is obtained, which, after reacting with acid, turns into phenol:

2. Industrial method: the catalytic oxidation of cumene in air produces phenol and acetone:

3. From aromatic sulfonic acids by fusion with alkalis. The reaction most often carried out to produce polyhydric phenols is:

Chemical properties of phenols.

R The -orbital of the oxygen atom forms a single system with the aromatic ring. Therefore, the electron density on the oxygen atom decreases, and on the benzene ring it increases. Communication polarity HE increases, and the hydrogen of the hydroxyl group becomes more reactive and can easily be replaced by a metal atom even under the action of alkalis.

The acidity of phenols is higher than that of alcohols, so the following reactions can be carried out:

But phenol is a weak acid. If carbon dioxide or sulfur dioxide is passed through its salts, phenol is released, which proves that carbonic and sulfurous acids are stronger acids:

The acidic properties of phenols are weakened by the introduction of type I substituents into the ring and enhanced by the introduction of type II.

2) Formation of esters. The process occurs under the influence of acid chlorides:

3) Electrophilic substitution reaction. Because HE-group is a substituent of the first kind, then the reactivity of the benzene ring in the ortho- and para-positions increases. When phenol is exposed to bromine water, a precipitate is observed - this is a qualitative reaction to phenol:

4) Nitration of phenols. The reaction is carried out with a nitrating mixture, resulting in the formation of picric acid:

5) Polycondensation of phenols. The reaction occurs under the influence of catalysts:

6) Oxidation of phenols. Phenols are easily oxidized by atmospheric oxygen:

7) A qualitative reaction to phenol is the effect of a solution of ferric chloride and the formation of a violet complex.

Application of phenols.

Phenols are used in the production of phenol-formaldehyde resins, synthetic fibers, dyes and medicines, and disinfectants. Picric acid is used as explosives.

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

Rice. 1.1. Phenol production methods

Table 1.3

Thus, the most expedient from an economic point of view is the currently most popular cumene process. 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 large amounts 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, Dow Chemical developed a process for the production of phenol, including the chlorination reaction of benzene and subsequent hydrolysis of monochlorobenzene ( process of catalytic hydrolysis of halogenated benzenes ). Independently, a similar technology was developed by the German company I.G. Farbenindustrie Co. Subsequently, the stage of obtaining monochlorobenzene and the stage of 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 into a mixture of cyclohexanone and cyclohexanol, which is further dehydrogenated to form phenol. In the 60s, Monsanto used this method for several years at one of its plants in Australia, but later transferred it to the cumene method for producing phenol.

4. In 1961, Dow Chemical of Canada implemented process through the 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 occur in the liquid phase. First reaction. oxidation of toluene. was used in Germany already during the Second World War to produce benzoic acid. The reaction proceeds under fairly mild conditions with high yield. The second stage is more difficult due to catalyst deactivation and low phenol selectivity. It is believed that performing this step in the gas phase may make the process more efficient. This method is currently used in practice, although its share of world phenol production is only about 5%.

5. The synthesis method by which most of the phenol produced in the world is obtained today - cumene process - discovered by a group of Soviet chemists led 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. Previously, hydroperoxides were considered low-stable 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 40s and is partly known as the Hock process, named after the German scientist who later independently discovered the cumene route for the synthesis of phenol. This method was first used on an industrial scale in the USA in the early 50s. 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 nature of the method, which requires increased capital costs and makes it difficult to achieve a high yield of phenol per starting benzene. Thus, if the useful product yield is 95% at each of the three stages, the final yield will be only 86%. Approximately this yield of phenol is obtained by the cumene method at present. But the most important and fundamentally unavoidable drawback of the cumene method is associated with the fact that acetone is formed as a by-product. This, which was initially seen as a strength of the method, is becoming an increasingly serious problem as acetone does not find an equivalent market. In the 90s, this problem became especially noticeable after the creation of new methods for the synthesis of methyl methacrylate by oxidation of C4 hydrocarbons, which sharply reduced the need for acetone. The severity of the situation is evidenced by the fact that Japan has developed a technology that involves recycling acetone. For this purpose, two more stages are added to the traditional cumene scheme, the hydrogenation of acetone into isopropyl alcohol and the dehydration of the latter into propylene. The resulting propylene is again returned to the benzene alkylation stage. In 1992, Mitsui launched a large-scale phenol production (200 thousand tons/year), based on this five-stage cumene technology.

Rice. 1.2. Acetone recycling to produce propylene

Other similar modifications to the cumene method have also been 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 aimed at finding new routes for the synthesis of phenol, which would be based on the direct oxidation of benzene, has become particularly intensive in the last decade. Work is carried out mainly in the following areas: oxidation with molecular oxygen, oxidation with monoatomic oxygen donors and conjugate oxidation. Let us consider in more detail the directions of searching for new ways of phenol synthesis.

Phenol (hydroxybenzene,carbolic acid) – ThisOorganicoth aromatic compound with formulaOuchC6H5OH. Belongs to the class of the same name - phenols.

In its turn, Phenols is a class of organic compounds of the aromatic series in which hydroxyl groups OH− connected to the carbon of the aromatic ring.

Based on the number of hydroxyl groups, they are distinguished:

• monohydric phenols (arenols): phenol and its homologues;
• diatomic phenols (arenediols): pyrocatechin, resorcinol, hydroquinone;
• triatomic phenols (arenetriols): pyrogallol, hydroxyhydroquinone, phloroglucinol;
• polyhydric phenols.

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

Properties of phenol

Freshly distilled phenol is colorless needle-shaped crystals with a melting point 41 °C and boiling point 182 °C. When stored, especially in a humid atmosphere and in the presence of small quantities of iron and copper salts, it quickly acquires a red color. Phenol can be mixed in any proportion with alcohol, water (when heated above 60 °C), highly soluble in ether, chloroform, glycerin, carbon disulfide.

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

At the hydroxyl group, phenol undergoes 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 - C6H5ONa):

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

• As a result of the interaction of phenol with sodium metal, 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

• When distilling phenol with zinc dust, the reaction of replacing 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 undergoes electrophilic substitution reactions on the aromatic ring. The OH group, being one of the strongest donor groups (due to a decrease in electron density on the functional group), increases the reactivity of the ring to these reactions and directs substitution to ortho- And pair- provisions. Phenol is easily 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

• 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 to 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 stability is much lower than that of benzene. Depending on the nature of the oxidizing agent and the reaction conditions, different products are obtained.

• Thus, under the action of hydrogen peroxide in the presence of an iron catalyst, a small amount of diatomic phenol, pyrocatechol, is formed:

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

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

Preparation of phenol

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

Coal tar from coke production contains from 0.01 to 0.1% phenols, in semi-coking products from 0.5 to 0.7%; in the oil formed during 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 that boils away at 160-250 °C. The composition of the phenolic fraction includes phenol and its homologues (25-40%), naphthalene (25-40%) and organic bases (pyridine, quinoline). Naphthalene is separated by filtration, and the remaining fraction is treated with a 10-14% solution of sodium hydroxide.

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, sequentially selecting phenol, cresols and xylenols.

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

Synthetic methods for producing phenol

1. By benzenesulfonate method benzene is mixed with oil of vitriol. 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 the release of sulfur dioxide begins and the phenol is distilled off.
2. Chlorobenzene method consists of direct chlorination of benzene with chlorine gas in the presence of iron or its salts and saponification of the resulting chlorobenzene with a solution of sodium hydroxide or hydrolysis in the presence of a catalyst.
3. Modified Raschig method is based on the oxidative chlorination of benzene with hydrogen chloride and air, followed by hydrolysis of chlorobenzene and the release of phenol by distillation.
4. Cumene method consists of alkylation of benzene, oxidation of the resulting isopropylbenzene into cumene hydroperoxide and its subsequent decomposition into phenol and acetone:
   Isopropylbenzene is obtained by reacting benzene with pure propylene or propane-propylene fraction of oil cracking, purified from other unsaturated compounds, moisture, mercaptans and hydrogen sulfide, which poison the catalyst. Aluminum trichloride dissolved in polyalkylbenzene, for example, is used as a catalyst. in diisopropylbenzene. Alkylation is carried out at 85 °C and excess pressure 0.5 MPa, which ensures the process occurs in the liquid phase. Isopropylbenzene is oxidized into hydroperoxide with atmospheric oxygen or technical oxygen at 110-130°С in the presence of metal salts of variable valency (iron, nickel, cobalt, manganese) Hydroperoxide is decomposed with dilute acids (sulfuric or phosphoric) or small amounts of concentrated sulfuric acid at 30-60 °C. After rectification, phenol, acetone and a certain amount are obtained α-methylstyrene. The industrial cumene method, developed in the USSR, is the most economically advantageous compared to other methods for producing phenol. The production of phenol through benzenesulfonic acid involves the consumption of large quantities 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 its hardware design and allows one to simultaneously obtain two technically valuable products: phenol and acetone.
5. During the oxidative decarboxylation of benzoic acid First, the liquid-phase catalytic oxidation of toluene into benzoic acid is carried out, which, in the presence of Cu 2+ converted to benzenesalicylic 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 the subsequent production of nylon and nylon).

During oil refining, phenol is used to purify oils 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). When phenol is inhaled, the functions of the nervous system are disrupted. Dust, vapors and phenol solution, if they come into contact with the mucous membranes of the eyes, respiratory tract, or 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 children 0.05-0.5 g.

Bibliography:
Kuznetsov E. V., Prokhorova I. P. 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., Müller K. Phenoplastics. M., Chemistry, 1978. 288 p.
Nikolaev A.F. Technology of plastics, Leningrad, Chemistry, 1977. 366 p.