The released bromine is separated by extraction with non-polar solvents or steam distillation. Physical and chemical properties of bromine

The discovery of bromine occurred in the first third of the 19th century; independently of each other, the German chemist Karl Jacob Loewich in 1825, and the Frenchman Antoine Jerome Balard in 1826 introduced the world to a new chemical element. Interesting fact - Balar originally named his element murid(from Latin muria- brine), because he made his discovery while studying the Mediterranean salt fields.

Bromine (from the ancient Greek βρῶμος, literally translated “smelly”, “stench”, “stink”) is an element of the main subgroup of group VII of the fourth period of the periodic table of chemical elements D.I. Mendeleev (in the new classification - an element of the 17th group). Bromine is a halogen, a reactive nonmetal, with atomic number 35 and molecular weight 79.904. The symbol is used to indicate Br(from Latin Bromum).

Finding bromine in nature

Bromine is a widespread chemical element and is found almost everywhere in the external environment. There is especially a lot of bromine in salt water - seas and lakes, where it is available in the form of potassium bromide, sodium bromide and magnesium bromide. The largest amount of bromine is formed during the evaporation of sea water; it is also found in some rocks, as well as in plants.

The human body contains up to 300 mg of bromine, mainly in the thyroid gland; bromine also contains blood, kidneys and pituitary gland, muscles and bone tissue.

Physical and chemical properties of bromine

Bromine is usually a caustic heavy liquid, has a red-brown color and a sharp, very unpleasant (smelly) odor. It is the only non-metal that is in a liquid state at room temperature.

Bromine (as well as bromine vapor) is a toxic and poisonous substance; when working with it, it is necessary to use chemical protective equipment, because bromine causes burns when it comes into contact with human skin and mucous membranes.

The composition of natural bromine is two stable isotopes (79 Br and 81 Br), the bromine molecule consists of two atoms and has the chemical formula Br 2.

The body's daily requirement for bromine

The need of a healthy body for bromine is no more than 0.8-1 g.

Along with the bromine present in the body, a person receives bromine from food products. The main suppliers of bromine are nuts (,), legumes (, and), as well as pasta, dairy products, algae and almost all types of sea fish.

Danger and harm of bromine

Elemental bromine is a potent poison; it is strictly prohibited to take it orally. Bromine vapor can cause pulmonary edema, especially in those who are prone to allergic reactions or have diseases of the lungs and respiratory tract (bromine vapor is very dangerous for asthmatics).

Signs of excess bromine

An excess of this substance usually occurs with an overdose of bromine preparations; it is categorically undesirable for people, because it can pose a real health hazard. The main signs of excess bromine in the body are inflammation and rashes on the skin, disruptions in the digestive system, general lethargy and depression, persistent bronchitis and rhinitis not associated with colds and viruses.

Signs of bromine deficiency

A lack of bromine in the body is manifested by insomnia, slow growth in children and adolescents, and a decrease in the level of hemoglobin in the blood, but these symptoms are not always associated with an insufficient amount of bromine, so to confirm suspicions, you need to visit a doctor and take the necessary tests. Often, due to a lack of bromine, the risk of spontaneous abortion (miscarriage at different stages, up to the third trimester) increases.

Beneficial properties of bromine and its effect on the body

Bromine (in the form of bromides) is used for various diseases, its main effect is sedative, therefore bromine preparations are often prescribed for nervous disorders and sleep disorders. Bromine salts are an effective treatment for diseases that cause seizures (especially epilepsy), as well as disorders of the cardiovascular system and some gastrointestinal ailments (stomach and duodenal ulcers).

Bromine digestibility

The absorption of bromine is slowed down by aluminum, and, therefore, you should take medications containing bromine salts only after consulting a doctor.

Contrary to unsubstantiated rumors (more like anecdotes), bromine does not have a depressing effect on the libido and potency of men. Allegedly, bromine in the form of a white powder is added to the food of young soldiers in the army, as well as male patients in mental health centers and prisoners in prisons and colonies. There is no scientific evidence for this, and rumors can be explained by the ability of bromine (its preparations) to have a calming effect.

According to some sources, bromine helps to activate sexual function in men and increase both the volume of ejaculate and the number of sperm contained in it.

Use of bromine in life

Bromine is used not only in medicine (potassium bromide and sodium bromide), but also in other areas, for example in photography, oil production, and in the production of motor fuel. Bromine is used in the manufacture of chemical warfare agents, which once again emphasizes the need for careful handling of this element.

The content of the article

BROMINE(Bromum, Br) – element 17 (VIIa) of group of the periodic table, atomic number 35, relative atomic mass 79.904. Natural bromine consists of two stable isotopes: 79 Br (50.69 at.%) and 81 Br (49.31 at.%), and a total of 28 isotopes are known with mass numbers from 67 to 94. In chemical compounds, bromine exhibits oxidation states from –1 to +7, occurs in nature exclusively in the oxidation state –1.

History of discovery.

Three scientists came close to the discovery of bromine almost simultaneously, but only one of them was destined to become the officially recognized discoverer.

In 1825, the young French chemist Antoine-Jérôme Balard, who worked as a preparator at the Pharmacological School at the University of the small southern town of Montpellier, began his first independent scientific research. Since ancient times, Montpellier has been famous for its salt mines. To extract salt, pools were dug on the seashore and filled with sea water. After the water evaporated under the influence of sunlight, the fallen salt crystals were scooped out, and the remaining mother liquor (brine) was returned back to the sea.

Balar's supervisor, Professor Joseph Anglada, tasked him with studying the chemical composition of the drained brine and coastal seaweed. Acting on brine with various reagents, Bolar noticed that when chlorine is passed through it, the solution acquires an intense yellow color. Chlorine and alkaline extracts of algae ash were stained similarly. At first, Balar suggested that the observed color was caused by the presence of iodine in the samples under study, which, when reacting with chlorine, forms an unknown substance. To begin with, he extracted it successively with ether and aqueous potassium hydroxide. Having treated the resulting alkaline solution with pyrolusite (MnO 2) in a sulfuric acid environment, Balar isolated an unpleasant-smelling red-brown liquid and tried to separate it into its component parts. When all attempts failed, it became clear that this was a new element. Having determined the density and boiling point of the liquid, as well as studying its most important chemical properties, on November 30, 1825, Balard sent a report on his experiments to the Paris Academy of Sciences. In it, in particular, the name “murid” was proposed for the new element (from the Latin word “muria” - brine).

A commission of three chemists was appointed to verify the message: Louis Nicolas Vauquelin, Louis Jacques Thénard and Joseph Gay-Lussac. Having repeated the described experiments, they confirmed Balar’s conclusions, but the name “murid” was considered unsuccessful, because that hydrochloric acid was then called acidum muriaticum - muric (from the hypothetical element muria), and its salts - muriates, and the use of such similar names “murid” and “murium” could cause misunderstandings. According to the recommendation of the nomenclature committee at the Academy of Sciences, it was proposed to name the new element bromine from the Greek brwmoV - fetid. In Russia, the name “bromine” was not immediately established; for a long time, the names “vrom”, “murid”, and “vromid” were used for element No. 35.

It later turned out that it was not Balar who first obtained elemental bromine, but a student of the famous German chemist Leopold Gmelin, Carl Jacob Löwig, Leopold Gmelin, who isolated it from spring water in Kreuznach in 1825 at the University of Heidelberg. While he was preparing more of the drug for research, Balar's message appeared.

The famous German chemist Justus Lubich came close to the discovery of bromine, just like Balard, who mistook it for a compound of chlorine and iodine.

It can be said that the discovery of bromine lay on the surface, and the French chemist Charles Frédéric Gerhardt even said that “It was not Balard who discovered bromine, but bromine who discovered Balard.”

In nature, bromine is almost always found together with chlorine as an isomorphic impurity in natural chlorides (up to 3% in sylvite KCl and carnallite KCl MgCl 2 6H 2 O). Own bromine minerals: bromargyrite AgBr, bromosylvinite KMgBr 3 ·6H 2 O and embolite Ag(Br, Cl) are rare and have no industrial significance. They were discovered much later than elemental bromine (bromargyrite - in Mexico, in 1841). Clarke (average content in the earth's crust) of bromine in the earth's crust is 2.1·10 –4%.

A large amount of bromine is found in the Earth’s hydrosphere (about 3/4 of that present in the earth’s crust): in the oceans (6.6·10–3%), salt lakes, underground brines and groundwater. The highest concentration of dissolved bromides - about 6 mg/l - is observed in the water of the Dead Sea, and the total amount of bromine in it is estimated at 1 billion tons. Together with splashes of salt water, bromine compounds enter the atmosphere.

Bromine is also found in living organisms. The bromine content in living phytomass is 1.6·10–4%. In the human body, the average concentration of bromine is about 3.7 mg/kg, most of it concentrated in the brain, liver, blood and kidneys. Among the inorganic anions that make up the blood, bromide ion ranks fifth in quantity after chloride, bicarbonate, phosphate and sulfate; its concentration in blood plasma is in the range of 20–150 µmol/l. Some animals, fungi and plants (primarily legumes) are capable of accumulating bromine, especially in marine fish and algae.

Obtaining bromine.

Industrial production of bromine began in 1865 at the Strassfurt salt mine in Germany; two years later, bromine began to be mined in the USA, in the state of Virginia. In 1924, on board the ship Ethila, the possibility of extracting bromine from sea water was demonstrated, and in 1934 industrial production based on this method was organized. In Russia, the first bromine plant was built in 1917 on the Saki salt lake.

All industrial methods for producing bromine from brine solutions are based on its displacement by chlorine from bromides:

MgBr 2 + Cl 2 = MgCl 2 + Br 2

When producing bromine by blowing, the feedstock (brine from salt lakes, associated waters from oil wells, sea water) is acidified with sulfuric acid to pH 3.5 and treated with an excess amount of chlorine. The brine containing dissolved bromine is then fed to the top of a column filled with small ceramic rings. The solution flows down the rings, and a powerful stream of air is blown towards it, and the bromine passes into the gas phase. The bromine-air mixture is passed through a solution of sodium carbonate:

3Na 2 CO 3 + 3Br 2 = 5NaBr + NaBrO 3 + 3CO 2

To separate bromine from the resulting mixture of bromide and sodium bromate, it is acidified with sulfuric acid:

5NaBr + NaBrO 3 + 3H 2 SO 4 = 3Na 2 SO 4 + 3Br 2 + 3H 2 O

Other proposed methods for extracting bromine from chlorinated brine: extraction with hydrocarbons or adsorption with ion exchange resins are not widely used.

Some of the bromide solutions used in industry (up to 35% in the USA) are sent for recycling to obtain additional amounts of bromine.

World bromine production (as of 2003) was about 550 thousand tons per year, most of it produced in the USA (39.4%), Israel (37.6%), and China (7.7%). The dynamics of bromine production in different countries of the world are shown in Table 1.

Table 1. Dynamics of global bromine production

Table 1. DYNAMICS OF WORLD BROMINE PRODUCTION(in thousand tons).
A country	1999	2000	2001	2002	2003
USA	239	228	212	222	216
Israel	181	210	206	206	206
China	42	42	40	42	42
Great Britain	55	32	35	35	35
Jordan	–	–	–	5	20
Japan	20	20	20	20	20
Ukraine	3	3	3	3	3
Azerbaijan	2	2	2	2	2
France	1,95	2	2	2	2
India	1,5	1,5	1,5	1,5	1,5
Germany	0,5	0,5	0,5	0,5	0,5
Italy	0,3	0,3	0,3	0,3	0,3
Turkmenistan	0,15	0,15	0,15	0,15	0,15
Spain	0,1	0,1	0,1	0,1	0,1
Total in the world	547	542	523	540	548

The price of elemental bromine ranges from $700 to $1,000 per ton. Russia's annual need for bromine is estimated at 20–25 thousand tons, it is satisfied mainly by imports from the USA and Israel.

In the laboratory, bromine can be prepared by reacting bromides with a suitable oxidizing agent, such as potassium permanganate or manganese dioxide, in an acidic environment.

MnO 2 + 2H 2 SO 4 + 2NaBr = Br 2 + MnSO 4 + Na 2 SO 4

The released bromine is separated by extraction with non-polar solvents or steam distillation.

Simple substance.

In the solid, liquid and gaseous state, bromine exists in the form of diatomic molecules Br 2, noticeable dissociation into atoms begins only at 800 ° C, dissociation also occurs under the influence of light. The element bromine is a strong oxidizing agent, it reacts directly with almost all non-metals (except the noble gases, oxygen, nitrogen and carbon) and many metals, these reactions are often accompanied by ignition (for example, with phosphorus, antimony, tin):

2S + Br 2 = S 2 Br 2

2P + 3Br 2 = 2PBr 3 ; PBr 3 + Br 2 = 2PBr 5

2Al + 3Br 2 = 2AlBr 3

Ni + Br 2 = NiBr 2

Many metals react slowly with anhydrous bromine due to the formation of a film of bromide on their surface, which is insoluble in bromine. Of the metals, the most resistant to bromine (even at elevated temperatures and in the presence of moisture) are silver, lead, platinum and tantalum. Gold, unlike platinum, easily reacts with it, forming AuBr 3 .

In an aqueous environment, bromine oxidizes nitrites to nitrates, ammonia to nitrogen, iodides to free iodine, sulfur and sulfites to sulfuric acid:

2NH 3 + 6Br 2 = N 2 + 6HBr

3Br 2 + S + 4H 2 O = 6HBr + H 2 SO 4

Bromine is moderately soluble in water (3.58 g per 100 g at 20° C); when this solution is cooled to 6° C, garnet-red crystals of bromine clathrate hydrate with the composition 6Br 2 46H 2 O fall out of it. The solubility of bromine increases significantly at adding bromides due to the formation of strong complex compounds:

KBr + Br 2 = KBr 3

In an aqueous solution of bromine (“bromine water”), there is an equilibrium between molecular bromine, bromide ion and bromine oxoacids:

Br 2 + H 2 O = HBr + HBrO

In a saturated solution, bromine is dissociated by 0.85%, in a 0.001-molar solution - by 17%.

When bromine water is stored in the light, it gradually decomposes with the release of oxygen due to photolysis of hypobromous acid:

2HOBr+ hv= 2HBr + O2

When bromine reacts with alkali solutions, the corresponding bromides and hypobromites (in the cold) or bromates are formed:

Br 2 + 2NaOH = NaBr + NaBrO + H 2 O (at t

3Br 2 + 6NaOH = 5NaBr + NaBrO 3 + 3H 2 O

Due to the high chemical activity of bromine, tanks with an internal lead or nickel lining are used for its transportation. Small volumes of bromine are stored in glass containers.

Bromine compounds.

Hydrogen bromide HBr, is a toxic (maximum permissible concentration = 2 mg/m3) colorless gas with a pungent odor, fuming in air due to interaction with water vapor. When cooled to –67°C, hydrogen bromide becomes liquid. HBr is highly soluble in water: at 0° C, 612 volumes of hydrogen bromide dissolve in one volume of water; in solution, HBr dissociates into ions:

HBr + H 2 O = H 3 O + + Br –

An aqueous solution of HBr is called hydrobromic acid; it is one of the strong acids (pK a = –9.5). In HBr, bromine has an oxidation state of –1 and therefore hydrobromic acid exhibits reducing properties; it is oxidized by concentrated sulfuric acid and atmospheric oxygen (in the light):

H 2 SO 4 + 2HBr = Br 2 + SO 2 + 2H 2 O

4HBr + O 2 = 2Br 2 + 2H 2 O

When interacting with metals, as well as with metal oxides and hydroxides, hydrobromic acid forms salts - bromides:

HBr + KOH = KBr + H2O

In industry, hydrogen bromide is obtained by direct synthesis from elements in the presence of a catalyst (platinum or activated carbon) H 2 + Br 2 = 2HBr and, as a by-product, during the bromination of organic compounds:

In the laboratory, HBr can be obtained by the action of concentrated phosphoric acid on alkali metal bromides when heated:

NaBr + H3PO4 = NaH2PO4 + HBr

A convenient laboratory method for the synthesis of HBr is also the reaction of bromine with benzene or decalin in the presence of iron:

C 10 H 18 + Br 2 = C 10 H 17 Br + HBr

Hydrogen bromide is used to produce bromides and some organic bromine compounds.

Potassium bromide KBr– a colorless crystalline substance, highly soluble in water (65 g in 100 g of water at 20° C), melting point = 730° C. Potassium bromide is used in the manufacture of photographic emulsions and as an anti-veiling agent in photography. KBr transmits infrared rays well and therefore serves as a lens material for IR spectroscopy.

Lithium bromide LiBr, is a colorless hygroscopic substance (t pl = 552° C), highly soluble in water (63.9% at 20° C). The crystalline hydrate LiBr 2H 2 O is known. Lithium bromide is obtained by reacting aqueous solutions of lithium carbonate and hydrobromic acid:

Li 2 CO 3 + 2HBr = 2LiBr + H 2 O + CO 2

Lithium bromide is used in the treatment of mental illness and chronic alcoholism. Due to its high hygroscopicity, LiBr is used as a drying agent in air conditioning systems and for the dehydration of mineral oils.

Hypobromous acid HOBr belongs to weak acids, it exists only in dilute aqueous solutions, which are obtained by reacting bromine with a suspension of mercury oxide:

2Br 2 + 2HgO + H 2 O = HgO HgBr 2 Ї + 2HOBr

Salts of hypobromous acid are called hypobromites, they can be obtained by reacting bromine with a cold alkali solution ( see above), when alkaline solutions are heated, hypobromites disproportionate:

3NaBrO = 2NaBr + NaBrO 3

The oxidation state of bromine +3 corresponds to Bromic acid HBrO 2, which is currently not received. Only its salts are known - bromites, which can be obtained by oxidation of hypobromites with bromine in an alkaline medium:

Ba(BrO) 2 + 2Br 2 + 4KOH = Ba(BrO 2) 2 + 4KBr + 2H 2 O

Bromic acid HBrO 3 was obtained in solutions by the action of dilute sulfuric acid on solutions of its salts – bromates:

Ba(BrO 3) 2 + H 2 SO 4 = 2HBrO 3 + BaSO 4 Ї

When attempting to obtain solutions with a concentration higher than 30%, bromic acid decomposes explosively.

Bromic acid and bromates are strong oxidizing agents:

2S + 2NaBrO 3 = Na 2 SO 4 + Br 2 + SO 2.

Potassium bromate KBrO 3 – a colorless crystalline substance, soluble in water (6.9 g of KBrO 3 dissolves in 100 g of water at 20° C, 49.7 g at 100° C). When heated to 434° C, it decomposes without melting:

2KBrO 3 = 2KBr + 3O 2

Potassium bromate is obtained by electrolysis of KBr solutions or by reacting potassium hydroxide with bromine and chlorine:

12KOH + Br 2 + 5Cl 2 = 2KBrO 3 + 10KCl +6H 2 O

KBrO 3 is used in analytical chemistry as an oxidizing agent during bromatometric titration; it is part of neutralizers for perms.

The most stable of the bromine oxoacids is bromic acid HBrO 4, which exists in aqueous solutions with a concentration not exceeding 6 mol/l. Despite the fact that HBrO 4 is the most powerful oxidizing agent among bromine oxygen acids, redox reactions with its participation proceed very slowly. For example, bromic acid does not release chlorine from a one-molar solution of hydrochloric acid, although this reaction is thermodynamically favorable. The special stability of the BrO 4 ion is due to the fact that oxygen atoms, surrounding the bromine atom in a tetrahedron, effectively protect it from the attack of the reducing agent. Solutions of bromic acid can be obtained by acidifying solutions of its salts - perbromates, which, in turn, are synthesized by electrolysis of solutions of bromates, as well as by oxidation of alkaline solutions of bromates with fluorine or xenon fluorides:

NaBrO 3 + XeF 2 + 2NaOH = NaBrO 4 + 2NaF + Xe + H 2 O

Due to the strong oxidizing properties of perbromates, they were synthesized only in the second half of the 20th century. American scientist Evan H.Appelman in 1968.

Bromine oxygen acids and their salts can be used as oxidizing agents.

Biological role and toxicity of bromine compounds.

Many aspects of the biological role of bromine have not yet been clarified. In the human body, bromine is involved in the regulation of the thyroid gland, as it is a competitive inhibitor of iodine. Some researchers believe that bromine compounds are involved in the activity of eosinophils - cells of the immune system. Eosinophil peroxidase oxidizes bromide ions to hypobromous acid, which helps destroy foreign cells, including cancer cells. Lack of bromine in food leads to insomnia, slow growth and a decrease in the number of red blood cells in the blood. The daily intake of bromine in the human body through food is 2–6 mg. Fish, cereals and nuts are especially rich in bromine.

The element bromine is poisonous. Liquid bromine causes hard-to-heal burns; if it gets on the skin, it must be washed off with plenty of water or soda solution. Bromine vapor at a concentration of 1 mg/m 3 causes irritation of the mucous membranes, cough, dizziness and headache, and at a higher concentration (>60 mg/m 3) it causes suffocation and death. In case of bromine vapor poisoning, it is recommended to inhale ammonia. The toxicity of bromine compounds is less great, however, with prolonged use of bromine-containing drugs, chronic poisoning can develop - bromism. Its symptoms are general lethargy, the appearance of a skin rash, apathy, and drowsiness. Bromide ions, entering the body for a long time, prevent the accumulation of iodine in the thyroid gland, inhibiting its activity. To speed up the removal of bromine from the body, a diet high in salt and plenty of fluids are prescribed.

Application of bromine and its compounds.

The first known use of bromine compounds was in the production of purple dye. It was extracted back in the second millennium BC from mollusks of the “murex” species, which accumulate bromine from sea water. The process of extracting the dye was very labor-intensive (from 8,000 shellfish you can get only 1 gram of purple) and only very rich people could afford to wear clothes dyed with it. In ancient Rome, only representatives of the highest authorities could wear it, which is why it was called “royal purple.” The structure of the active principle of this dye was established only in the second half of the 19th century; it turned out to be a bromine compound - 6.6" - dibromoindigo. Indigo bromine derivatives, synthesized artificially, are used for dyeing fabrics (mainly cotton) even now.

In the 19th century The main areas of use of bromine compounds were photography and medicine.

Silver bromide AgBr began to be used as a light-sensitive material around 1840. Modern photographic materials based on AgBr make it possible to take photographs with a shutter speed of 10–7 seconds. To make photographic film based on silver bromide, this salt is synthesized in an aqueous solution of gelatin, while the precipitated AgBr crystals are evenly distributed throughout the entire volume of the solution. After the gelatin hardens, a fine suspension is formed, which is evenly applied in a thin layer (2 to 20 microns thick) onto the surface of the carrier - a transparent film made from cellulose acetate. Each square centimeter of the resulting layer contains several hundred million grains of silver bromide surrounded by a gelatin film. When light hits such a photographic film, photolytic decomposition of AgBr occurs:

AgBr+ hv= Ag + Br

The reverse process - oxidation of silver with bromine - in the photoemulsion is prevented by gelatin. Photolysis leads to the formation in AgBr microcrystals of groups of silver atoms with dimensions of 10–7–10–8 cm, the so-called latent image centers. To obtain a visible image, silver bromide in exposed areas is reduced to metallic silver. The latent image centers catalyze (accelerate) the reduction reaction and allow it to be carried out practically without affecting the unilluminated AgBr crystals. After dissolving the remaining silver bromide, a black and white image (negative) is obtained on photographic film, resistant to light. To create a positive image, you need to repeat the process by shining a light on (usually) photographic paper through the film containing the negative image.

Bromine salts have proven to be very effective medicines for the treatment of many nervous diseases. The famous Russian physiologist I.P. Pavlov said: “Humanity should be happy that it has such a precious drug for the nervous system as bromine.” The medical use of KBr as a sedative (sedative) and anticonvulsant in the treatment of epilepsy began in 1857. At that time, aqueous solutions of potassium and sodium bromide were known collectively as bromine. For a long time, the mechanism of action of bromine preparations remained unknown; it was believed that bromides reduce excitability, acting similarly to sleeping pills. Only in 1910, one of Pavlov’s students, P.M. Nikiforovsky, experimentally showed that bromides enhance inhibition processes in the central nervous system. Now sodium and potassium bromides have practically fallen out of use in the treatment of nervous diseases. They were replaced by more effective organobromine drugs.

At the beginning of the 20th century. A new area of application for bromine has opened up. With the spread of automobiles, there was a need for large quantities of cheap gasoline, but the existing oil industry at that time could not produce the required volumes of high-octane fuel. To improve the quality of the fuel - reducing its ability to detonate in the engine - in 1921, the American engineer Thomas Midgley proposed introducing an additional component into gasoline - tetraethyl lead (Pb(C 2 H 5) 4, TPP). This additive proved to be very effective, but with its use a new problem arose - lead deposits in engines. To avoid their formation, TES is dissolved in bromohydrocarbons - 1,2-dibromoethane (BrCH 2 CH 2 Br) and ethyl bromide (C 2 H 5 Br), the resulting mixture is called “ethyl liquid” ( cm. OCTANE NUMBER). The mechanism of its action is that during the joint combustion of bromine hydrocarbons and thermal power plants, volatile lead bromides are formed, which are removed from the engine along with the exhaust gases. In the middle of the last century, most of the bromine produced was consumed in the production of ethyl liquid - 75% in 1963. Now the use of ethyl liquid does not meet modern environmental safety requirements and its global production is declining: in Russia, for example, the share of leaded (containing ethyl liquid) gasoline in total the volume of automobile fuel was more than 50% in 1995, and 0.4% in 2002. In Russia, the use of thermal power plants has been prohibited since 2003, and in some regions even earlier (in Moscow - since 1993).

Now the main area of bromine use is the production of fire retardants (from 40% of world bromine consumption). Fire retardants are substances that protect materials of organic origin from fire. They are used for impregnation of fabrics, wood and plastic products, and production of non-flammable paints. Mainly aromatic bromo derivatives are used as fire retardants: dibromostyrene, tetrabromophthalic anhydride, decabromodiphenyl oxide, 2,4,6-tribromophenol and others. Bromochloromethane is used as a filler in fire extinguishers designed to extinguish electrical wiring.

A significant portion of bromine (in the USA - 24%) in the form of calcium, sodium and zinc bromides is consumed to make drilling fluids, which are pumped into wells to increase the volume of oil produced.

Up to 12% of bromine is used for the synthesis of pesticides and insecticides used in agriculture and to protect wood products (methyl bromide).

Elemental bromine and its compounds are used in water purification and water treatment processes. Bromine is sometimes used for mild disinfection of water in swimming pools with increased sensitivity to chlorine. 7% of the bromine produced is spent for these purposes.

About 17% of bromine is consumed in the production of photographic materials, pharmaceuticals and high-quality rubber (bromobutyl rubber).

Organic bromine compounds are used for inhalation anesthesia (halothane - 1,1,1-trifluoro-2-chloro-2-bromoethane, CF 3 CHBrCl), as analgesics, sedatives, antihistamines and antibacterial drugs, in the treatment of peptic ulcers, epilepsy, cardiac -vascular diseases. The isotope of bromine with atomic mass 82 is used in medicine in the treatment of tumors and in studying the behavior of bromine-containing drugs in the body.

Bromobutyl rubber is produced industrially by incomplete bromination of butyl rubber - a copolymer of 97-98% isobutylene CH 2 =C(CH 3) 2 and ne 2-3% isoprene CH 2 =C(CH 3)CH=CH 2. In this process, only the isoprene units of the rubber macromolecule are brominated:

–CH 2 –C(CH 3)=CH–CH 2– + Br 2 = –CH 2 –CBr(CH 3) –CHBr–CH 2 –

The introduction of bromine into butyl rubber significantly increases the rate of its vulcanization. Bromobutyl rubber is odorless, does not emit harmful substances during storage and processing, it is characterized by a high degree of co-vulcanization with unsaturated rubbers and better adhesion to other polymers than butyl rubber. Halogenated butyl rubbers are used for sealing rubber products made from other polymers (for example, in the production of car tires), for the production of heat-resistant transport tapes with high abrasion resistance, rubber stoppers, and chemically resistant container linings.

Yuri Krutyakov

Literature:

Miller V. Bromine. L., State Institute of Applied Chemistry. 1967
Figurovsky N.A. Discovery of elements and origin of their names. M., Nauka, 1970
Popular library of chemical elements. M., Nauka, 1983
Inorganic chemistry, vol. 2. Ed. Yu.D. Tretyakov. M., Academy, 2004
U.S. Geological Survey, Mineral Commodity Summaries, January 2004

Example 1. Write an equation for the bromination reaction of 2-methylbutane. Write and name the isomers of the resulting compound using the international nomenclature.

The solution of the problem. Let us recall the rules for naming organic substances according to the International Nomenclature (IUPAC).

The IUPAC nomenclature is constructed as follows: the longest chain of carbon atoms is selected and numbered, numbering starts from the end closest to which the substituent radical is located. In the presence of

several substituents, the sum of the numbers indicating their position in the chain should be the smallest. In the name of a substance, the location of the substituent is indicated by a number, the substituent itself is named, and then the main chain is named according to the number of carbon atoms with the addition of a suffix corresponding to a particular class of organic compounds. If radicals are repeated, then numbers indicating their position are listed, and the number of identical radicals is indicated by the prefixes di-, tri-, tetra-, etc.

By the name of the substance we determine what the main chain is in the specified hydrocarbon. Let's write and number the chain of carbon atoms. Let's identify substitutes. Using the names of substituent radicals, we write them at the corresponding carbon atoms in the main chain. We check the hydrocarbon formula, monitor the number of hydrogen atoms in each carbon atom, taking into account that the valence of the carbon atom in organic compounds is equal to four. The main chain is butane and contains four carbon atoms. The second carbon atom has a methyl group. The formula of the original compound is:

When writing reaction equations for saturated hydrocarbons, to which the original hydrocarbon belongs, you should know that these hydrocarbons are characterized by substitution reactions, and the substitution reaction is easiest for hydrogen at the tertiary carbon atom, then at the secondary and most difficult at the primary carbon atom. In this case, the substitution occurs at the second carbon atom, since it is tertiary.

We compose the isomer formulas for the resulting halogenated hydrocarbon. First, we write down the isomers of halogen derivatives, in which the main chain of carbon atoms contains 5 carbon atoms.

Now we write down an isomer containing 3 carbon atoms in the main chain.

Example 2. What reaction products are formed during the nitration of 2,4-dimethylpentane under the conditions of the Konovalov reaction?

The solution of the problem. When nitrating 2,5-dimethylhexane under the conditions of the Konovalov reaction (t = 140 0 C, 14–20% HNO 3 solution, elevated pressure), the product of hydrogen atom substitution is predominantly formed at tertiary carbon atoms C 2 or C 4. Since the molecule has an axis of symmetry, there will be one product - 2-nitro-2,4-dimethylpentane. Side processes accompanying nitration reactions are the splitting of the carbon chain (mainly near the branch) and the formation of nitro derivatives with a smaller number of carbon atoms. The longer the alkane chain and the higher the temperature, the more intense this process occurs. In this problem there will be no such products: they are formed during the vapor-phase nitration of alkanes (t = 300 o C)

Using the name of the substance, we write down the formula of the resulting saturated hydrocarbon:

The preparation of alkanes from halogen derivatives by the Wurtz reaction is carried out by the interaction of two halogen derivatives with a smaller number of carbon atoms than in the synthesized compound, in the presence of metallic sodium. To select suitable halogen derivatives, you need to divide the alkane formula into any two fragments, which must combine with halogen atoms at the site of separation. In a mixture of two halogen derivatives with sodium metal, the reaction can take place between two halogen derivatives that are different in structure and two pairs of identical halogen derivatives. As a result, in the first case, three alkanes are formed - one main and two secondary. According to the conditions of the problem, to obtain an alkane without the formation of by-products, it is necessary to divide the original hydrocarbon into two identical fragments, which form one halogen derivative. This is only possible for symmetrical alkanes. The desired hydrocarbon is symmetrical and we divide it in this way:

The Wurtz reaction equation has the form:

At the first stage, we will carry out intramolecular dehydration of alcohol.

Bromine? Presence trace elements in the human body calculated in very small quantities, because these are substances of which there is less than 0.015 g in our body. Of the mass of an organ or tissue, their content is thousandths of a percent or less (10 -2 to 10 -7%), therefore they are also called trace elements. But, despite such a meager presence, a sufficient amount of these substances is an important condition for the full functioning of all systems and organs. One of these minerals is . About him properties and health significance will be discussed in this article, the main directions of its use for therapeutic and prophylactic purposes.

Bromine: The Story of Discovery

Interesting history of the discovery of bromine, the last remaining white spot among the halogens. At the same time, two chemists isolated it from different substances: in 1825, a student at the University of Heidelberg K. Levig when exposed to chlorine on mineral water and French chemist A. Balar, who studied swamp plants, - during the reaction of chlorine water with algae ash. However, while Levig was trying to obtain larger quantities of the new substance, Balard had already published a report on his discovery in 1826, thanks to which he gained worldwide fame. Balar wanted to call the resulting substance the Latin word “murid”, which means “brine”. However, hydrochloric acid was called muric acid, and the salts derived from it were called muriates, and in order to avoid terminological confusion in the scientific community, it was decided to call the discovered mineral bromine, which is translated from ancient Greek as “stench.” Bromine indeed has a suffocating, unpleasant odor. In Russian chemical science throughout the 19th century, this microelement was designated as vrom, vromid and murid.

Bromine in optimal natural form and dosage is found in beekeeping products - such as pollen, royal jelly and drone brood, which are part of many natural vitamin and mineral complexes of the Parapharm company: Leveton P, Elton P, Leveton Forte ", "Apitonus P", "Osteomed", "Osteo-Vit", "Eromax", "Memo-Vit" and "Cardioton". That is why we pay so much attention to each natural substance, talking about its importance and benefits for the health of the body.

Chemical and physical
properties of bromine

Story about chemical and physical properties of bromine Let us preface it with a description of its place in Mendeleev’s periodic table of chemical elements. In it it is located under symbolBr (from Latin Bromum) at number 35 in the 17th group, where there are halogens(fluorine, chlorine, bromine, iodine and astatine). These are non-metals and active oxidizing agents, not present in nature independently, but only as part of compounds, since they are characterized by high chemical reactivity, combining with almost all simple substances. There are only 2 elements whose simple substances exist in liquid form under normal conditions - mercury and bromine, and only one liquid non-metal - bromine, which is a red-brown, smoking brownish vapor, toxic liquid. Bromine crystallizes only at a temperature of -7.25 °C, and boils at +59 °C. It dissolves in H 2 O (the so-called bromine water is obtained), but better - in organic solvents.

Pure bromine represented by a 2-atomic molecule – BR 2, But high chemical activity does not allow it to be in a free state in nature, so it is found in composition of bromide(compounds with metals). In terms of content in the earth's interior and rocks, it ranks 50th, so its natural source is mostly salt lakes and seas; groundwater accompanying oil. It is also present in the air, more so in coastal areas. However, in the event of an industrial leak, bromine vapors have a poisonous and asphyxiating effect on people.

The properties of bromine allow it to be widely used for the production of fuel additives, pesticides in agriculture, combustion retardants, the photosensitive agent silver bromide in photography, and medicines. Working with this microelement requires extreme caution and compliance with safety precautions. Gloves, overalls and a gas mask are your best allies when dealing with this substance.

Bromine value
for the body person

Pure bromine– highly toxic substance! Only 3 grams elemental bromine causes poisoning if ingested, and 35 grams is lethal. Contact with liquid bromine is fraught with a painful, poorly healing burn. 0.001% bromine in the air causes coughing, choking, dizziness, nosebleeds, and exceeding this figure can lead to respiratory spasms and death. However, despite the toxicity, the importance of bromine for the body it's hard to downplay a person. He is a trace element contained in our organs and tissues: brain, blood, liver and kidneys, thyroid gland, muscle tissue and bones... We need it in small quantities!

Bromine has an effect on the central nervous system. Accumulating in the cerebral cortex, it regulates the activity of neurons, being responsible for the balance between excitation and inhibition reactions. If necessary, it enhances inhibition through membrane enzymes, which is responsible for its calming effect.

This microelement is also important for the endocrine system, since it acts as a kind of alternative to iodine and reduces the need of the thyroid gland for iodine, preventing its growth - the occurrence of endemic goiter.

Role of bromine in the functioning of the gastrointestinal tract due to its activating effect on digestive enzymes:

pepsin (necessary for the breakdown of proteins);
amylase (breaks down carbohydrates);
lipase (dissolves and sorts fats during digestion).

Question O influence of bromine on male sexual activity shrouded in myths. In particular, that previously prisoners in prisons, patients in psychiatric departments of hospitals and soldiers in the army were added to their food with this mineral in order to weaken erectile function. For a long time it was believed that bromine, having a general calming effect on the body, depresses the sexual sphere. However, later studies have proven a completely opposite effect from taking bromide preparations, contributing to the stabilization of the reproductive system in men, increase in seminal fluid and the number of sperm in it.

Bromine is removed from the body with urine and sweating. So its intake from the outside through food (and, if necessary, in pharmacological preparations) is necessary. However, its removal is a long process, so it is possible to increase its concentration in organs and tissues, which is very dangerous for health.

How does it affect bromine deficiency
on human health?

Bromine deficiency can cause a number of serious functional impairments. In childhood and adolescence, its deficiency can lead to slower growth, and for adults it can lead to a decrease in life expectancy. Problems with falling asleep, neurasthenic and hysterical manifestations, anemia caused by a drop in hemoglobin levels, an increased risk of spontaneous miscarriage in pregnant women, weakened sexual functions, digestive problems caused by decreased acidity - all this may be a consequence of a lack of this mineral. The causes of this condition are metabolic abnormalities or diuretic abuse means promoting bromine removal from the body. Diagnose lack of bromine and treatment must be prescribed by a specialist, and self-medication without consulting a doctor in this case is strictly not recommended.

Bromine overdose

No less dangerous bromine overdose, arising exclusively in connection with the use of pharmacological drugs. Its characteristic symptoms will be allergic skin rashes, inflammatory manifestations on the skin, disturbances in the gastrointestinal tract, depression and loss of energy, sleep problems, lethargy, bronchitis and rhinitis as a reaction to the toxic effect of bromine. The nervous system and organs of perception (vision and hearing) suffer, mental processes and cognitive (perception-related) functions deteriorate.

An excess of bromine can be fatal, so if you suspect an overdose, you should immediately stop using bromine-containing medications and consult a doctor to cancel them or adjust the dose.

Taking bromine drugs V
for therapeutic and preventive purposes

Studying exposure to bromide on human health and their introduction into medical practice began almost immediately after discovery of bromine– in the 19th century, so taking bromine medications– a proven remedy in clinical medicine.

Russian physiologist I. P. Pavlov made significant contributions to research on the impact bromine-containing compounds on nervous activity. His experiments on dogs proved effective bromine for neuroses, and appointed bromide doses should be correlated with the type of higher nervous activity (with a strong type, higher doses are required).

Bromides as sedatives used for neuropsychic disorders, insomnia, increased excitability, hysteria and neurasthenia, convulsions, but they have almost ceased to be used for the treatment of epilepsy. Today, doctors are generally cautious bromides are prescribed due to slow elimination from the body and the danger of developing bromism - chronic bromine intoxication. This indication remains valid bromine-containing medications, as a violation of coordination between the cerebral cortex and organs, systems, which often occurs with gastric and duodenal ulcers, at an early stage of the development of hypertension.

Among the common drugs containing bromine, – potassium bromide, sodium bromide, “Adonis-bromine”, “Bromcamphor” and others, both oral in the form of powders and solutions, and intravenous. Sodium bromide is applicable for electrophoresis – for painful inflammatory processes, for herpes zoster. Bromide dosage involves taking 0.1–1 gram three times a day.

Daily requirement for bromine

To increase the acidity of gastric juice and activation of sexual function in men, for the prevention of nervous disorders, doctors recommend taking 3–8 mg. This daily requirement for bromine for a healthy person. Many dietary supplements include this trace element along with other minerals. On average, 1 mg enters our body with food.

Bromine content
in products nutrition

Knowing what it's like bromine content in products nutrition, you can increase its intake without the use of pharmacological drugs. This trace element accumulates in many plants, which take it from the depths and bind it into organic non-toxic compounds and salts.

They are especially rich in:

peas,
beans,
lentils,
various nuts and
grain crops (barley, wheat, etc.).

It is taken into its composition from sea water

kelp and other algae,
sea fish.

We can also get some bromine from rock salt. It is also found in dairy products, pasta and bread products made from durum wheat.

Was the last of the halogens to be discovered by chemists. This event took place in the fall of 1885 in one of the laboratories of Heidelberg University, headed by Professor L. Gmelin. One of the students brought his teacher a flask containing some kind of brown liquid. This student was K. Levig, who told the professor that he was studying the composition of one of the mineral waters, and that he passed chlorine through the water and the solution turned brown. He isolated this substance from solution using ether. This was bromine. L. Gmelin became interested in the student’s work and asked him to prepare more of this substance in order to study its properties in detail.
This work required a long time, and the young student did not have it. While K. Levig was receiving new portions of bromine, an article was published in one of the scientific chemical journals, the author of which was A. Balard, who worked as a preparator in one of the pharmaceutical schools in the French town of Montpellier. He wrote in the article that while studying swamp vegetation since 1824, he conducted various experiments. And he managed to obtain a brown substance. He also studied ash obtained from seaweed. When he applied chlorine water to the ash, the solution separated into two layers, the upper one becoming brown in color, and the lower one becoming blue. He assumed that there was iodine at the bottom, which gave the typical color with starch. But what was in the top layer? He thought that a compound of chlorine and iodine had formed, but he could not isolate it. He hypothesized that it was a new unknown chemical element.

A. Balar isolated a red-brown liquid, exactly the same as K. Levig. Balar decided to name him murid, which means “pickle” in Latin. Friends advised him to send an article, or rather a report, to the Paris Academy of Sciences. The report was entitled "Memoir of a Special Substance Contained in Sea Water." The work suggested that this substance is similar to the halogens chlorine and iodine. A special commission was created at the academy, which checked whether a new chemical element had actually been obtained. Members of the commission confirmed that this is in fact true. But only they suggested calling this chemical element “bromine,” which translated means fetid, due to the unpleasant odor of the liquid.

History of discovery.

Three scientists came close to the discovery of bromine almost simultaneously, but only one of them was destined to become the officially recognized discoverer. In 1825, the young French chemist Antoine-Jérôme Balard, who worked as a preparator at the Pharmacological School at the University of the small southern town of Montpellier, began his first independent scientific research. Since ancient times, Montpellier has been famous for its salt mines. To extract salt, pools were dug on the seashore and filled with sea water. After the water evaporated under the influence of sunlight, the fallen salt crystals were scooped out, and the remaining mother liquor (brine) was returned back to the sea.

The famous German chemist Justus Lubich came close to the discovery of bromine, just like Balard, who mistook it for a compound of chlorine and iodine.

Obtaining bromine.

MgBr 2 + Cl 2 = MgCl 2 + Br 2

When producing bromine by blowing, the feedstock (brine from salt lakes, associated water from oil wells, sea water) is acidified with sulfuric acid to pH 3.5 and treated with an excess amount of chlorine. The brine containing dissolved bromine is then fed to the top of a column filled with small ceramic rings. The solution flows down the rings, and a powerful stream of air is blown towards it, and the bromine passes into the gas phase. The bromine-air mixture is passed through a solution of sodium carbonate:

To separate bromine from the resulting mixture of bromide and sodium bromate, it is acidified with sulfuric acid:

5NaBr + NaBrO 3 + 3H 2 SO 4 = 3Na 2 SO 4 + 3Br 2 + 3H 2 O

Other proposed methods for extracting bromine from chlorinated brine: extraction with hydrocarbons or adsorption with ion exchange resins are not widely used.

Some of the bromide solutions used in industry (up to 35% in the USA) are sent for recycling to obtain additional amounts of bromine.

World bromine production (as of 2003) was about 550 thousand tons per year, most of it produced in the USA (39.4%), Israel (37.6%), and China (7.7%).

In the laboratory, bromine can be prepared by reacting bromides with a suitable oxidizing agent, such as potassium permanganate or manganese dioxide, in an acidic environment.

MnO 2 + 2H 2 SO 4 + 2NaBr = Br 2 + MnSO 4 + Na 2 SO 4

The released bromine is separated by extraction with non-polar solvents or steam distillation.

Simple substance.

Bromine is the only non-metal that is liquid at room temperature. Elemental bromine is a heavy red-brown liquid with an unpleasant odor (density at 20° C - 3.1 g/cm 3, boiling point +59.82° C), bromine vapor has a yellow-brown color. At a temperature of –7.25° C, bromine solidifies, turning into red-brown needle-shaped crystals with a weak metallic luster. In solid, liquid and gaseous states, bromine exists in the form of diatomic molecules Br 2, noticeable dissociation into atoms begins only at 800° C, dissociation also occurs under the influence of light. The element bromine is a strong oxidizing agent, it reacts directly with almost all non-metals (except the noble gases, oxygen, nitrogen and carbon) and many metals, these reactions are often accompanied by ignition (for example, with phosphorus, antimony, tin):

2S + Br 2 = S 2 Br 2

2P + 3Br 2 = 2PBr 3 ; PBr 3 + Br 2 = 2PBr 5

2Al + 3Br 2 = 2AlBr 3

Ni + Br 2 = NiBr 2

In an aqueous environment, bromine oxidizes nitrites to nitrates, ammonia to nitrogen, iodides to free iodine, sulfur and sulfites to sulfuric acid:

3Br 2 + S + 4H 2 O = 6HBr + H 2 SO 4

KBr + Br 2 = KBr 3

In an aqueous solution of bromine (“bromine water”), there is an equilibrium between molecular bromine, bromide ion and bromine oxoacids:

Br 2 + H 2 O = HBr + HBrO

In a saturated solution, bromine is dissociated by 0.85%, in a 0.001-molar solution - by 17%.

When bromine water is stored in the light, it gradually decomposes with the release of oxygen due to photolysis of hypobromous acid:

When bromine reacts with alkali solutions, the corresponding bromides and hypobromites (in the cold) or bromates are formed:

Br 2 + 2NaOH = NaBr + NaBrO + H 2 O (at t< 0° C)

3Br 2 + 6NaOH = 5NaBr + NaBrO 3 + 3H 2 O

Due to the high chemical activity of bromine, tanks with an internal lead or nickel lining are used for its transportation. Small volumes of bromine are stored in glass containers.

Bromine compounds.

Chemical compounds of bromine are known in which it can exhibit oxidation states of –1, 0, +1, +3, +5 and +7. Of greatest practical interest are substances containing bromine in the oxidation state –1, these include hydrogen bromide, as well as inorganic and organic bromides. Bromine compounds in positive oxidation states are represented mainly by bromine oxygen acids and their salts; they are all strong oxidizing agents. Hydrogen bromide HBr, is a toxic (maximum permissible concentration = 2 mg/m3) colorless gas with a pungent odor, fuming in air due to interaction with water vapor. When cooled to –67°C, hydrogen bromide becomes liquid. HBr is highly soluble in water: at 0° C, 612 volumes of hydrogen bromide dissolve in one volume of water; in solution, HBr dissociates into ions:

HBr + H 2 O = H 3 O + + Br –

4HBr + O 2 = 2Br 2 + 2H 2 O

When interacting with metals, as well as with metal oxides and hydroxides, hydrobromic acid forms salts - bromides:

HBr + KOH = KBr + H2O

In the laboratory, HBr can be obtained by the action of concentrated phosphoric acid on alkali metal bromides when heated:

NaBr + H3PO4 = NaH2PO4 + HBr

A convenient laboratory method for the synthesis of HBr is also the reaction of bromine with benzene or decalin in the presence of iron:

C 10 H 18 + Br 2 = C 10 H 17 Br + HBr

Hydrogen bromide is used to produce bromides and some organic bromine compounds.

Hypobromous acid HOBr belongs to weak acids, it exists only in dilute aqueous solutions, which are obtained by reacting bromine with

The released bromine is separated by extraction with non-polar solvents or steam distillation. Physical and chemical properties of bromine

Finding bromine in nature

Physical and chemical properties of bromine

The body's daily requirement for bromine

Danger and harm of bromine

Signs of excess bromine

Signs of bromine deficiency

Beneficial properties of bromine and its effect on the body

Bromine digestibility

Use of bromine in life

History of discovery.

Obtaining bromine.

Simple substance.

Bromine compounds.

Biological role and toxicity of bromine compounds.

Application of bromine and its compounds.

Bromine: The Story of Discovery

Chemical and physical properties of bromine

Bromine value for the body person

How does it affect bromine deficiencyon human health?

Bromine overdose

Taking bromine drugs V for therapeutic and preventive purposes

Daily requirement for bromine

Bromine content in products nutrition

History of discovery.

Obtaining bromine.

Simple substance.

Bromine compounds.

Chemical and physical
properties of bromine

Bromine value
for the body person

How does it affect bromine deficiency
on human health?

Taking bromine drugs V
for therapeutic and preventive purposes

Bromine content
in products nutrition