The 53rd element of Mendeleev’s periodic table, iodine, was discovered 200 years ago, this is an indisputable fact, but who discovered it is still debated. Several people were involved in this discovery: Bernard Courtois, Humphry Davy and Joseph Louis Gay-Lussac.

Three contenders

The Frenchman Courtois owned a plant for the production of saltpeter; he was not only an industrialist, but also a researcher. At some point, he began to notice that some unknown substance was corroding the pipes at the enterprise. Legend has it that Courtois the cat was the first to “discover” iodine. There were 2 flasks on the table: one with sulfuric acid, the other with a solution of seaweed ash in ethyl alcohol. The cat threw them onto the floor, as a result of which both liquids mixed, purple smoke rose, which then settled into shiny dark purple crystals.

Courtois decided that he had discovered a new substance; he named it “iodos”, which means “violet” in Greek, because of its color. This was in 1813. Courtois did not consider himself a scientist, did not claim priority in the discovery of iodine, he asked his chemist friends to check the results of the experiments and describe the new substance. They did this, but did not publish the results of the research, but only presented them at a scientific meeting.

At this time, the famous English scientist Humphry Davy arrived in Paris. He became interested in the new substance, carried out research in his field laboratory, realized that it was a new element, and named it “iodine.”

The famous Frenchman Gay-Lussac received samples of the new substance for study and spent almost 2 years to refute Davy’s conclusions, but in the end, as an honest and conscientious scientist, he admitted Davy’s correctness publicly.

It turns out that Courtois was the first to isolate iodine, Davy investigated it, and Gay-Lussac published the results of his research. IN English language iodine is called “yodin” to emphasize the priority of Devi; in other languages ​​the name “iodine” has been established.

Why do you need iodine?

The beneficial properties of iodine have been used for a long time: back in the 3rd millennium BC. In China, healers isolated iodine from sea sponges and algae and made a tincture for healing wounds.

IN modern history In Russia, the famous surgeon Nikolai Pirogov was the first to use iodine for disinfection. And today we all use alcohol tincture of iodine in everyday life to treat abrasions and scratches.

The human body also contains iodine, it is only 25 milligrams, but the importance of iodine for the body is very great. Iodine is concentrated mainly in the thyroid gland. The meaning of the “thyroid gland” for humans in ancient times was unknown, so it was believed that the human soul lived in it.

Iodine is one of the microelements, substances found in the body in small quantities, but playing an important role. Iodine is part of the hormone thyroxine, which is produced by the thyroid gland and controls the metabolism of proteins, fats and carbohydrates, i.e. metabolism in the body.

Thyroxine and the iodine it contains influence the mental and physical state of a person, the functional state of the central nervous system depends on them. nervous system and emotional stability. Thyroxine also affects the functioning of the liver and cardiovascular system.

If you don't have enough iodine

If a person develops it, it causes a disease called endemic goiter, the production of thyroxine is disrupted, the thyroid gland increases in size and its functions are impaired.

This disease has been known for a long time and is very common; people suffer from it in regions where the level of iodine in water, food and soil is significantly reduced.

Due to iodine deficiency, a child's growth and mental development, a consequence of iodine deficiency can be cretinism. Severe forms of goiter can lead to the formation of a malignant tumor.

In Russia, this problem is very acute: more than 60% of the territory of our country is included in the zone of iodine deficiency. This number includes many areas middle zone, and the Urals, Yakutia, Udmurtia, North Caucasus.

According to endocrinologists, 15-20% of residents of the central part of Russia have an enlarged thyroid gland. According to statistics, almost 90% of children in Moscow have a lack of iodine, many of them also have an enlarged thyroid gland. Pregnant women living in regions of iodine deficiency often experience miscarriages and premature babies. From these serious illnesses Only consuming enough iodine can protect it.

Where can I get iodine for the body?

Iodine enters the body in two forms - mineral (inorganic) and organic. Mineral iodine not associated with any organic molecule, example: alcohol solution of iodine.
Organic iodine is in chemical bond with organic substances: sugars, polysaccharides, amino acids.

The mineral iodine easily penetrates the blood and enters into chemical reactions with organic substances, changing their quality or destroying them.

Organic iodine is in a bound state and practically does not enter into chemical reactions with organic substances present in the body. The body itself controls the amount of incoming organic iodine; excess iodine is naturally eliminated from the body.

Therefore, the use of such iodine in combination with other components and microelements is safe for the body and helps improve thyroid function and improve hormonal balance.
An excellent source of organic iodine is seaweed and other seafood.

How to provide the body with enough iodine? Obvious advice: you need to include seafood containing a large number of iodine: seaweed, sea ​​fish, shrimp, crabs, etc., since these products contain maximum amount Yoda. But any heat treatment destroys most of the iodine the body needs, and most of us do not have the opportunity to eat freshly salted and freshly prepared fish, and besides, not everyone likes the specific taste of some seafood.

Innovative health products DOCTOR SEA will help provide the body with a sufficient amount of organic iodine and other microelements in the most digestible form.

Introduction

Everyone knows iodine. Having cut our finger, we reach for a bottle of Iodine, or rather its alcohol solution. But not everyone knows how important the iodine content is in our body. Iodine is a very strong antiseptic. However, iodine serves not only to lubricate abrasions and scratches. Although Iodine is only 25 mg in the human body, it plays an important role. Most of the “human Iodine” is found in the thyroid gland: it is part of a substance that regulates metabolism in the body. With a lack of iodine, physical and mental development and a disease called endemic goiter occurs. This happens in high mountain areas where the natural content of iodine in air, water and food is very low.

A little history.

Description of the element.

Iodine - chemical element Group VII of Mendeleev's periodic system. Atomic number - 53. Relative atomic mass 126.9045 (Fig. 1). Halogen. Of the halogens found in nature, it is the heaviest, unless, of course, you count the radioactive short-lived astatine. Almost all natural Iodine consists of atoms of one - a single isotope with a mass number I 127, its content in the earth's crust is 4 * 10 -5% by mass. Radioactive Iodine I 125 is formed during natural radioactive transformations. Of the artificial isotopes of Iodine, the most important is Iodine I 131 and Iodine I 133. they are mainly used in medicine.

I 2 - halogen Dark gray crystals with a metallic luster. Flying It dissolves poorly in water, well - in organic solvents (with a purple or brown color of the solution) or in water with the addition of salts - iodides. Weak oxidizing and reducing agent. Reacts with concentrated sulfuric and nitric acids, metals, non-metals, alkalis, hydrogen sulfide. Forms compounds with other halogens.

The molecule of elemental Iodine, like other halogens, consists of two atoms. Iodine is the only halogen that exists in a solid state at normal conditions. Beautiful dark blue Yodine crystals are most similar to graphite. A distinct crystalline structure (Fig. 2), the ability to conduct electric current - all these “metallic” properties are characteristic of pure Iodine.

Discovery of Yoda.

The end of the 17th and beginning of the 18th centuries were marked by incessant wars in Europe. A lot of gunpowder was required and, therefore, a lot of saltpeter. The production of saltpeter took on an unprecedented scale; along with ordinary plant raw materials, seaweed was also used. A new chemical element was discovered in them.

One of the French saltpeter makers was the chemist and industrialist Bernard Courtois (1777-1838); he was a very observant person. It is believed that this is what helped him become the discoverer of the new chemical element Iodine in 1811. One day he noticed that the copper cauldron in which the lye obtained from fucus, kelp and others was evaporated brown algae, quickly collapses, as if some kind of acid is corroding it. Courtois decided to find out what was going on. Having precipitated and removed sodium salts from the solution, he evaporated the solution, found potassium sulfide in the boiler and, in order to decompose it, added concentrated sulfuric acid to the precipitate - and then purple smoke appeared. Courtois repeated the experiment, this time in a retort, and shiny black lamellar crystals settled in the retort receiver.

Sodium iodide from algae, interacting with sulfuric acid, releases iodine I 2 ; At the same time, sulfur dioxide is formed - sulfur dioxide SO 2 and water:

2NaI + 2H 2 SO 4 =I 2 + SO 2 +Na 2 SO 4 + 2H 2 O

When cooled, the Yoda vapor turned into dark gray crystals with a bright shine. Courtois wrote: “The mother liquor of algae-derived lye contains a fairly large amount of an unusual substance. It is easy to isolate: to do this, just add sulfuric acid to this solution and heat the mixture in a retort... The new substance is deposited in the receiver in the form of a black powder, which, when heated, turns into a magnificent vapor purple».

He assigned the name to the new element in 1813 French chemist Joseph-Louis Gay-Lussac (1778-1850) for the violet color of his vapors (“Yodos” means “purple” in Greek). He also obtained many derivatives of a new element - hydrogen iodide. HI, Yodic acid HIO 3 , Iodine(V) oxide I 2 O 5 , Iodine chloride ICl and others. Almost simultaneously, the elemental nature of Yod was proved by the English chemist Humphry Davy (1778-1829).

Food products contain a lot of iodine: eggs, milk, fish; there is a lot of iodine in seaweed, which is sold in the form of canned food, dragees and other products;

the first Iodine plant in Russia was built in 1915 in Yekaterinoslavl (now Dnepropetrovsk); received Iodine from the ash of the Black Sea algae Phyllophora; during the First World War, 200 kg of Iodine were produced at this plant;

if a thundercloud is “seeded” with silver iodide or lead iodide, then instead of hail, snow pellets are formed in the cloud: a cloud seeded with such salts sheds rain and does not harm the fields.

For many of us, a bottle of 5% alcohol solution of iodine in the first aid kit is a mandatory, familiar and not at all surprising phenomenon.

Chemistry as a science and the chemical industry are two areas of human activity that are closely related to each other. Progress in one area invariably causes progress in another. No one doubts the statement that all types of industrial chemistry are built on the achievements of the science of chemistry. Examples of such influence can be given infinite set. But it is often possible to trace the reverse influence of production itself on the development of chemical science.

A striking example of such influence chemical industry industry on the development of chemistry itself - the history of the discovery of iodine. This element was discovered in 1811 by the Parisian saltpeter manufacturer Bernard Courtois (1777–1838). It is noteworthy that the discovery itself did not occur in the chemical laboratory of any scientist or research institute, but directly at the plant, during production activities person. How did it happen?

In France, during the Napoleonic Wars, large quantities of saltpeter were required to produce gunpowder. Saltpeter was first imported from India, but there was not enough of it. True, by this time rich deposits of Chilean saltpeter had already been discovered in South America. But this saltpeter was not potassium, but sodium, and had the very unpleasant property of attracting moisture from the air (dampening), which made it unsuitable for the production of gunpowder. In Spain, back in 1808, a method was found for converting sodium nitrate into potassium nitrate using ash obtained by burning seaweed for this purpose. This is exactly what Courtois did at his small factory in Dijon, France.
He had long noticed that the products obtained from the ashes of seaweed, which were thrown up in abundance by the ocean tides onto the coast of France, contained some substance that had a corrosive effect on iron and copper vessels. But neither Courtois himself nor his assistants knew how to isolate this substance from algae ash. An accident helped speed up the discovery.
Stories from that time claimed that at the plant where saltpeter was produced, workers somehow chased a cat. Fleeing from her pursuers, the cat accidentally knocked over a vessel with sulfuric acid onto the remains of salts from the production of nitrate, and then suddenly thick purple vapors emerged from the resulting mixture.
How plausible is this story in the light of modern chemical knowledge? Indeed, sulfuric acid, acting on iodide salts of alkali metals (KI, NI), releases hydrogen iodide (HI). As a fragile substance, it decomposes in the presence of sulfuric acid, releasing free iodine:
Н2SO4 + 2НI = 2Н2О + SO2 + I2.
Courtois became interested in this phenomenon and began to carefully study the new substance. Within the limits of his knowledge and capabilities, he studied it in some detail and came to a number of important discoveries: he found that violet vapors, when cooled, settle in the form of black crystals with a metallic sheen, that the new substance combines with hydrogen, phosphorus, metals, and with ammonia it forms extremely explosive. It was nitrogen iodide NI3, a black powder that explodes easily when slightly shaken or even touched.
Courtois reported his observations and conclusions to two of his friends from Dijon - N. Clément and S. B. Desormes. Clement carried out all the experiments that Courtois told him about, became convinced of the complete validity of his conclusions, and in January 1813 he made a small report to the scientists of Paris about the mysterious substance. A secondary announcement of the discovery was made by Clément in November of the same year. None of these messages were published in the press. However, it has been preserved short description discovery made in the journal “Annals of Chemistry” for 1813, in which the role of Courtois was not forgotten.

“The new substance,” the message said, “is appearance– metal. Its specific gravity is about 4. The metal is very volatile; the smell of its vapors is similar to the smell of chlorine. It imparts a reddish-brown color (which disappears after a short time) paper and hands. This substance is neither acid nor alkali. When heated in a closed retort, it evaporates calmly, at a temperature of about 75° Celsius, boils under water, forming magnificent purple vapors; and when sublimated in significant quantities, it forms large shiny plates, which, however, are never massive. It is slightly soluble in water, better in alcohol and even better in ether.”
The new substance attracted the attention of two famous scientists - the French J.L. Gay-Lussac and the English G. Davy, who independently began to study its properties. Soon a rather passionate scientific debate arose between these scientists. Davy was the first to come to the conclusion that the new substance was an element similar to chlorine, discovered by K.V. Scheele. Gay-Lussac did not agree with Davy’s conclusions for a long time, but under the pressure of the latter’s evidence, he finally had to admit the correctness of his views.
Now that the substance was recognized as an element and the debate between these scientists about its nature had already ceased, it was necessary to give it a name. Gay-Lussac called it iodine, and Davy called it iodine. When establishing the name, both scientists proceeded from the same feature - the violet color of the vapor of the substance (from the Greek - violet). Nowadays, in all countries of the world, including Russia, the first name is used - iodine, and only in England the name iodine has been preserved. According to these names, the symbol for element I was adopted.
Gay-Lussac devoted a lot of time to studying the new element. In 1814, his extensive work on iodine was published, in which he substantiated the theory of hydrogen acids (hydroxy acids), described in detail the most important compounds of iodine and established by comparison various reactions substances with chlorine and iodine, that chlorine is “stronger than iodine”.

Where, for some reason, iodine suddenly becomes a rare guest, the number of deaf and deformed weak-minded people with goiters increases sharply. Paradoxical but true: in the 18th century. in the center of Europe in French Switzerland, entire villages were inhabited by “beings pleasing to God.” Moreover, there were so many holy fools that there was practically no one to serve in the army. For this very reason, Napoleon Bonaparte “had” to take on an unusual mission and become the first statesman, who ordered a systematic examination of goiter among his subjects.
As time went. And already from the second half of the 19th century century, iodine began to be used as an antiseptic for any operation: from tooth extraction to limb amputation, and this reduced the mortality rate of operations to 20 percent - a number that amazed the imagination of surgeons who were not accustomed to doing without postoperative complications. In 1883, the Swiss surgeon T. Kocher drew attention to the development of signs of cretinism (retardation of mental and physical development) after removal of the thyroid gland due to goiter. But the link between iodine and goiter was not taken seriously until Baumann discovered iodine in thyroid tissue in 1896.
Do you know that:
Academician V.I. Vernadsky believed that cosmic rays play a large role in the formation of iodine in the earth’s crust, which cause nuclear reactions in the earth’s crust, that is, the transformation of some elements into others. These transformations can produce very small amounts of new atoms in rocks, including iodine atoms.
Just 0.6% iodine added to hydrocarbon oils reduces frictional work in stainless steel and titanium bearings many times over. This allows you to increase the load on rubbing parts by more than 50 times.
Iodine is used to make special Polaroid glass. Crystals of iodine salts are introduced into glass (or plastic), which are distributed strictly regularly. Vibrations of the light beam cannot pass through them in all directions. The result is a kind of filter, called a Polaroid, which diverts the oncoming blinding stream of light. This type of glass is used in cars. By combining several polaroids or rotating polaroid glasses, exceptionally colorful effects can be achieved - this phenomenon is used in film technology and in the theater.
The iodine content in human blood depends on the time of year: from September to January the iodine concentration in the blood decreases, from February a new rise begins, and in May - June the iodine level reaches highest level. These fluctuations have a relatively small amplitude, and their causes still remain a mystery.
The first iodine plant in Russia was built in 1915 in Yekaterinoslav (now Dnepropetrovsk); obtained iodine from the ash of the Black Sea algae Phyllophora; During the First World War, 200 kg of iodine was produced at this plant.
If a thundercloud is “seeded” with silver iodide or lead iodide, then instead of hail, fine snow pellets are formed in the cloud: a cloud seeded with such salts rains and does not harm the crops.
According to World Organization healthcare, today almost 3 billion of the world's population (that is, one in three) are iodine deficient, and about 20 million of them suffer from mental retardation.

Everyone is familiar with iodine or iodine. Having cut our finger, we reach for a bottle of iodine, or rather its alcohol solution...
Nevertheless, this element is highly unique and each of us, regardless of education and profession, has to rediscover it more than once. The history of this element is also peculiar.

First acquaintance with iodine

Iodine was discovered in 1811 by the French chemist-technologist Bernard Courtois (1777-1838), the son of the famous saltpeter maker. During the years of the Great French Revolution, he already helped his father “extract from the bowels of the earth the main element of weapons to defeat tyrants,” and later took up the production of saltpeter on his own.
At that time, saltpeter was obtained in so-called saltpeter containers, or burts. These were heaps made up of plant and animal waste mixed with construction waste, limestone, and marl. The ammonia formed during decay was oxidized by microorganisms first into nitrogenous HN02, and then into nitric acid HNO3, which reacted with calcium carbonate, converting it into nitrate Ca(N03)2. It was removed from the mixture hot water, and then potash was added. The reaction was Ca (N0 3) a + K 2 C0 3 → 2KN0 3 + CaCO ↓.
The potassium nitrate solution was poured from the sediment and evaporated. The resulting crystals of potassium nitrate were purified by additional recrystallization.
Courtois was not a simple artisan. After working in a pharmacy for three years, he received permission to attend lectures on chemistry and study in the laboratory of the Ecole Polytechnique in Paris with the famous Fourcroix. He applied his knowledge to the study of seaweed ash, from which soda was then extracted. Courtois noticed that the copper boiler in which the ash solutions were evaporated was being destroyed too quickly. After evaporation and precipitation of crystalline sodium and potassium sulfates, their sulfides and, apparently, something else remained in the mother solution. By adding concentrated sulfuric acid to the solution, Courtois discovered the release of violet vapors. It is possible that something similar was observed by Courtois’ colleagues and contemporaries, but it was he who was the first to move from observations to research, from research to conclusions.
These are the conclusions (we quote an article written by Courtois): “The mother liquor of algae-derived lye contains a fairly large amount of an unusual and curious substance. It's easy to highlight. To do this, it is enough to add sulfuric acid to the mother solution and heat it in a retort connected to the receiver. The new substance... precipitates as a black powder, which when heated turns into a magnificent purple vapor. These vapors condense in the form of shiny crystalline plates, having a luster similar to that of crystalline lead sulfide... The amazing color of the vapors of the new substance makes it possible to distinguish it from all hitherto known substances, and other remarkable properties are observed in it, which gives its discovery the greatest interest.” .
In 1813, the first scientific publication about this substance appeared, chemists began to study it different countries, including such scientific luminaries as Joseph Gay-Lussac and Humphry Davy. A year later, these scientists established the elemental nature of the substance discovered by Courtois, and Gay-Lussac named the new element iodine - from the Greek - dark blue, violet.
Second acquaintance: ordinary and unusual properties.

Iodine is a chemical element of group VII periodic system. Atomic number - 53. Atomic mass - 126.9044. Halogen. Of the halogens found in nature, it is the heaviest, unless, of course, you count the radioactive short-lived astatine. Almost all natural iodine consists of atoms of a single isotope with a mass number of 127. Radioactive iodine - 125 is formed as a result of the spontaneous fission of uranium. Of the artificial isotopes of iodine, the most important are iodine - 131 and iodine - 133; they are used in medicine.
The elemental iodine molecule, like other halogens, consists of two atoms. Iodine is the only halogen that exists in a solid state under normal conditions. Beautiful dark blue iodine crystals are most similar to graphite. A distinct crystalline structure, the ability to conduct electric current - all these “metallic” properties are characteristic of pure iodine.
But, unlike graphite and most metals, iodine very easily goes into a gaseous state. It is even easier to convert iodine into vapor than into liquid.
To melt iodine, you need quite low temperature: + 113.5° C, but, in addition, it is necessary that the partial pressure of iodine vapor above the melting crystals be at least one atmosphere. In other words, iodine can be melted in a narrow-necked flask, but not in an open laboratory dish. In this case, iodine vapor does not accumulate, and when heated, the iodine will sublimate - it will go into a gaseous state, bypassing the liquid state, which usually happens when this substance is heated. By the way, the boiling point of iodine is not much higher than the melting point, it is only 184.35 ° C.
But not only the ease of transfer to a gaseous state iodine stands out among other elements. For example, its interaction with water is very peculiar.
Elemental iodine does not dissolve well in water: at 25°C only 0.3395 g/l. Nevertheless, you can obtain a much more concentrated aqueous solution of element No. 53 by using the same simple technique that doctors use when they need to preserve iodine tincture (3- or 5% solution of iodine in alcohol) longer: so that the iodine tincture does not fizzle out , add a little potassium iodide KI to it. The same substance also helps to obtain iodine-rich aqueous solutions: iodine is mixed with a not too diluted solution of ralium iodide.
KI molecules are capable of attaching molecules of elemental iodine. If one molecule reacts on each side, red-brown potassium triiodide is formed. Potassium iodide can add a larger number of iodine molecules, resulting in compounds of various compositions up to K19. These substances are called polyiodides. Polyiodides are unstable, and their solution always contains elemental iodine, and in a much higher concentration than what can be obtained by direct dissolution of iodine.
In many organic solvents - carbon disulfide, kerosene, alcohol, benzene, ether, chloroform - iodine dissolves easily. The color of non-aqueous solutions of iodine is not constant. For example, its solution in carbon disulfide is purple, and in alcohol it is brown. How can we explain this?
Obviously, violet solutions contain iodine in the form of molecules 12. If the result is a solution of a different color, it is logical to assume the existence of iodine compounds with the solvent in it. However, not all chemists share this point of view. Some of them believe that the differences in the color of iodine solutions are explained by the existence of various types of forces connecting the molecules of the solvent and the dissolved substance.
Violet solutions of iodine conduct electricity, since in solution the molecules 12 partially dissociate into 1+ and I- ions. This assumption does not contradict the ideas about the possible valences of iodine. Its main valencies are: 1" (such compounds are called iodides), 5+ (iodates) and 7+ (periodates). But iodine compounds are also known in which it exhibits valencies of 1+ and 3+, playing the role of a monovalent or trivalent metal There is a compound of iodine with oxygen, in which element No. 53 is octavalent - IO4.
But most often, iodine, as befits a halogen (there are seven electrons on the outer shell of the atom), exhibits a valence of 1“. Like other halogens, it is quite active - it reacts directly with most metals (even noble silver is resistant to iodine only at temperatures up to 50°C), but is inferior to chlorine and bromine, not to mention fluorine. Some elements - carbon, nitrogen, oxygen, sulfur, selenium - do not react directly with iodine.

third meeting:

It turns out that there is less iodine on Earth than lutetium
Iodine is a fairly rare element. Its clarke (content in the earth's crust in weight percent) is only 4-10~5%. It is less than the most difficult to obtain elements of the lanthanide family - thulium and lutetium.
Iodine has one feature that makes it similar to “rare earths” - extreme dispersion in nature. Although far from being the most abundant element, iodine is present literally everywhere. Even in seemingly ultra-pure rock crystals, micro-impurities of iodine are found. In transparent calcites, the content of element No. 53 reaches 5-10~6%. Iodine is found in soil, sea and river water, plant cells and animal organisms. But there are very few minerals rich in iodine. The most famous of them is lautarite Ca(IO 5) 2. But there are no industrial deposits of lautarite on Earth.
To obtain iodine, it is necessary to concentrate natural solutions containing this element, for example, water from salt lakes or associated oil waters, or to process natural iodine concentrators - seaweed. A ton of dried seaweed (kelp) contains up to 5 kg of iodine, while a ton of sea water contains only 20-30 mg.
Like most vital elements, iodine cycles in nature. Since many iodine compounds are highly soluble in water, iodine is leached from igneous rocks and carried into the seas and oceans. Sea water, evaporating, raises masses of elemental iodine into the air. Namely elemental: compounds of element No. 53 in the presence of carbon dioxide are easily oxidized by oxygen to 12.
The winds that carry air masses from the ocean to the mainland, iodine is also transferred, which, along with precipitation falls on the ground, enters the soil, groundwater, and living organisms. The latter concentrate iodine, but, dying, return it to the soil, from where it is again washed away by natural waters, enters the ocean, evaporates, and everything starts anew. This is only a general diagram in which all the details and chemical transformations that are inevitable at different stages of this eternal rotation are omitted.
And the iodine cycle has been studied very well, and this is not surprising: the role of microquantities of this element in the life of plants, animals, and humans is too great...

Iodine fourth introduction: biological functions of iodine

They are not limited to iodine tincture. We will not talk in detail about the role of iodine in plant life - it is one of the most important microelements; we will limit ourselves to its role in human life.
Back in 1854, the Frenchman Chatain, an excellent analytical chemist, discovered that the prevalence of goiter is directly dependent on the iodine content in the air, soil, and food consumed by people. Colleagues protested Chaten's conclusions; Moreover, the French Academy of Sciences recognized them as harmful. As for the origin of the disease, it was then believed that it could be caused by 42 causes - iodine deficiency did not appear on this list.
Almost half a century passed before the authority of the German scientists Baumann and Oswald forced French scientists to admit the mistake. Experiments by Bauman and Oswald showed that the thyroid gland contains a surprising amount of iodine and produces iodine-containing hormones. Lack of iodine initially leads to only a slight enlargement of the thyroid gland, but as it progresses, this disease - endemic goiter - affects many systems of the body. As a result, metabolism is disrupted and growth slows down. In some cases, endemic goiter can lead to deafness, cretinism... This disease is more common in mountainous areas and in places far from the sea.
The widespread spread of the disease can be judged even from works of art. One of the best female portraits by Rubens, “The Straw Hat”. U beautiful woman depicted in the portrait, swelling of the neck is noticeable (a doctor would immediately say: the thyroid gland is enlarged). Andromeda from the painting “Perseus and Andromeda” has the same symptoms. Signs of iodine deficiency are also visible in some people depicted in portraits and paintings by Rembrandt, Dürer, Van Dyck...
In our country, most of the regions of which are remote from the sea, the fight against endemic goiter is constantly carried out - primarily by means of prevention. The simplest and most reliable remedy is the addition of microdoses of Iodide to table salt.
It is interesting to note that history medicinal use Yoda goes back centuries. The healing properties of substances containing iodine were known 3 thousand years before this element was discovered. Chinese Code 1567 BC e. recommends seaweed for the treatment of goiter...
The antiseptic properties of iodine in surgery were first used by the French physician Buape. Oddly enough, the simplest dosage forms of iodine - aqueous and alcoholic solutions - did not find use in surgery for a very long time, although back in 1865-1866. the great Russian surgeon N.I. Pirogov used iodine tincture in the treatment of wounds.
The priority of preparing the surgical field with iodine tincture is erroneously attributed to the German doctor Grossikh. Meanwhile, back in 1904, four years before Grossikh, the Russian military doctor N.P. Filonchikov, in his article “Aqueous solutions of iodine as an antiseptic liquid in surgery,” drew the attention of surgeons to the enormous advantages of aqueous and alcoholic solutions of iodine precisely in preparation for surgery .
Needless to say, these simple drugs have not lost their significance to this day. It’s interesting that sometimes iodine tincture is also prescribed internally: a few drops per cup of milk. This can be beneficial for atherosclerosis, but you need to remember that iodine is useful only in small doses, and in large doses it is toxic.

Yod fifth acquaintance - purely utilitarian

Not only doctors are interested in iodine. It is needed by geologists and botanists, chemists and metallurgists.
Like other halogens, iodine forms numerous organoiodine compounds, which are included in the composition of some dyes.
Iodine compounds are used in photography and the film industry for the preparation of special photographic emulsions and photographic plates.
Iodine is used as a catalyst in the production of artificial rubbers.
The production of ultrapure materials - silicon, titanium, hafnium, zirconium - is also not complete without this element. The iodide method for producing pure metals is used quite often.
Iodine preparations are used as a dry lubricant for rubbing surfaces made of steel and titanium.
High-power incandescent iodine lamps are manufactured. The glass bulb of such a lamp is filled not with an inert gas, but with hearth vapors, which themselves emit light at high temperatures.
Iodine and its compounds are used in laboratory practice for analysis and in chemotron devices, the action of which is based on the redox reactions of iodine...
A lot of work of geologists, chemists and technologists goes into searching for iodine raw materials and developing methods for extracting iodine. Until the 60s of the last century, algae were the only source of industrial iodine production. In 1868, iodine began to be obtained from saltpeter production waste, which contains iodate and sodium iodide. Free raw materials and a simple method for obtaining iodine from saltpeter mother solutions ensured widespread distribution of Chilean iodine. First world war The supply of Chilean saltpeter and iodine stopped, and soon the lack of iodine began to affect the general state of the pharmaceutical industry in Europe. The search began for cost-effective ways to obtain iodine. In our country, already during the years of Soviet power, iodine began to be obtained from underground and oil waters of the Kuban, where it was discovered by the Russian chemist A.L. Potylitsin back in 1882. Later, similar waters were discovered in Turkmenistan and Azerbaijan.
But the iodine content in groundwater and associated waters from oil production is very low. This was the main difficulty in creating economically feasible industrial methods obtaining iodine. It was necessary to find a “chemical bait” that would form a fairly strong compound with iodine and concentrate it. Initially, this “bait” turned out to be starch, then copper and silver salts, which bound iodine into insoluble compounds. We tried kerosene - iodine dissolves well in it. But all these methods turned out to be expensive and sometimes flammable.
In 1930 Soviet engineer V.P. Denisovich developed the Coal method for extracting iodine from oil waters, and this method was the basis of Soviet iodine production for quite a long time. Up to 40 g of iodine accumulated in a kilogram of coal per month...
Other methods have also been tried. Already in recent decades it has been discovered that iodine is selectively sorbed by high-molecular ion-exchange resins. In the world's iodine industry, the ion exchange method is still used to a limited extent. There have been attempts to use it in our country, but the low iodine content and insufficient selectivity of ion exchangers for iodine have not yet allowed this, undoubtedly promising method, to radically transform the iodine industry.
Geotechnological methods for extracting iodine are also promising. They will make it possible to extract iodine from associated waters of oil and gas fields without pumping these waters to the surface. Special reagents introduced through a well will concentrate iodine underground, and not a weak solution, but a concentrate will flow to the surface. Then, obviously, the production of iodine and its consumption by industry will increase sharply - the complex of properties inherent in this element is very attractive to it.
IOD AND MAN. The human body not only does not need large quantities of iodine, but with amazing constancy maintains a constant concentration (10~5-10~6%) of iodine in the blood, the so-called iodine mirror of the blood. From total number Of iodine in the body, amounting to about 25 mg, more than half is found in the thyroid gland. Almost all the iodine contained in this gland is part of various derivatives of tyrosine - the thyroid hormone, and only a small part of it, about 1%, is in the form of inorganic iodine I1-.
Large doses of elemental iodine are dangerous: a dose of 2-3 g is lethal. At the same time, in the form of iodide, much larger doses can be taken orally.
If introduced into the body with food significant amount inorganic salts iodine, its concentration in the blood will increase 1000 times, but after 24 hours the iodine level in the blood will return to normal. The level of the iodine mirror strictly obeys the laws of internal metabolism and practically does not depend on the experimental conditions.
In medical practice, organoiodine compounds are used for x-ray diagnostics. Sufficiently heavy nuclei of iodine atoms scatter X-rays. When such a diagnostic agent is introduced into the body, exceptionally clear X-ray images of individual sections of tissues and organs are obtained.
UNDER AND COSMIC RAYS. Academician V.I. Vernadsky believed that cosmic rays play a large role in the formation of iodine in the earth's crust, which cause nuclear reactions in the earth's crust, that is, the transformation of some elements into others. Thanks to these transformations, very small amounts of new atoms, including iodine atoms, can be formed in rocks.
IODINE _ LUBRICANT. Just 0.6% iodine added to hydrocarbon oils greatly reduces the work of friction in bearings made of stainless steel and titanium. This allows you to increase the load on rubbing parts by more than 50 times.
IODINE AND GLASS. Iodine is used to make special Polaroid glass. Crystals of iodine salts are introduced into glass (or plastic), which are distributed strictly regularly. Vibrations of the light beam cannot pass through them in all directions. The result is a kind of filter, called a Polaroid, which diverts the oncoming blinding stream of light. This type of glass is used in cars. By combining several polaroids or rotating polaroid glasses, exceptionally colorful effects can be achieved - this phenomenon is used in film technology and in the theater.
DO YOU KNOW THAT:

• The iodine content in a person’s blood depends on the time of year: from September to January the iodine concentration in the blood decreases, from February a new rise begins, and in May - June the iodine level reaches its highest level. These oscillations have a relatively small amplitude, and their causes still remain a mystery;
• Food products contain a lot of iodine: eggs, milk, fish; there is a lot of iodine in seaweed, which goes on sale in the form of canned food, dragees and other products;
• the first iodine plant in Russia was built in 1915 in Yekaterinoslav (now Dnepropetrovsk); obtained iodine from the ash of the Black Sea algae Phyllophora; during the First World War, 200 kg of iodine was produced at this plant;
• if a thundercloud is “seeded” with silver iodide or lead iodide, then instead of hail, fine snow pellets are formed in the cloud: a cloud seeded with such salts sheds Rain and does not harm the crops.

Iodine was discovered in 1811 by the French chemist-technologist Bernard Courtois (1777-1838), the son of the famous saltpeter maker. Courtois was not a simple artisan. After working in a pharmacy for three years, he received permission to listen to lectures on chemistry and study in the laboratory of the Polytechnic School from the famous Parisian chemist and politician Fourcroy. Bernard Courtois began to study the ash of seaweed, from which soda was then extracted. He noticed that the copper boiler in which the ash solutions were evaporated was being destroyed too quickly. Carrying out a series of experiments, Courtois took two flasks, in one of which he placed sulfuric acid with iron, and in the other - seaweed ash with alcohol. During the experiments, his favorite cat sat on the scientist’s shoulder. One day he unexpectedly jumped off, knocking over the flasks and causing their contents to mix. Courtois saw that a purple cloud was rising above the puddle that had formed when the vessels fell.

Subsequently, by specially heating a mother (undiluted) solution of seaweed ash with concentrated sulfuric acid, he observed the release of “magnificent violet vapor,” which precipitated in the form of dark, shiny plate-like crystals. “The amazing color, unknown and unseen before, allowed us to conclude that a new substance had been obtained,” Courtois wrote in his memoirs.

In 1813, the first scientific publication about this substance appeared; chemists from different countries began to study it, including such luminaries of science as the French chemist Joseph Gay-Lussac and the English chemist Humphry Davy. A year later, these scientists proved the elementary nature of the substance discovered by Courtois, and Gay-Lussac named the new element iodine (from the Greek iodes, ioides - similar in color to a violet, dark blue, violet).

It is interesting to note that the history of the use of iodine in medicine goes back centuries. It is believed that the first reports of healing properties substances containing iodine appeared in China about three thousand years BC. Ancient healers isolated this element from sea sponges and algae and applied a cloth soaked in iodine to wounds so that they would not fester and heal faster.

The antiseptic (antimicrobial) properties of iodine were first used in surgery by the French physician Boinet. Oddly enough, the simplest medicinal forms of iodine - aqueous and alcoholic solutions - did not find use in surgery for a very long time, although back in 1865-1866 the great Russian surgeon N.I. Pirogov used iodine tincture in the treatment of wounds.

The priority of preparing the surgical field with iodine tincture is erroneously attributed to the German doctor Grossikh. Meanwhile, back in 1904, four years before Grossikh, the Russian military doctor N. Filonchikov, in his article “Aqueous solutions of iodine as an antiseptic liquid in surgery,” drew the attention of doctors to the enormous advantages of aqueous and alcoholic solutions of iodine specifically in preparation for surgery.

Priest Pavel Aleksandrovich Florensky is an outstanding theologian, philosopher and scientist, one of the remarkable representatives of Russian culture" Silver Age"After his arrest in a camp on the Solovetsky Islands, since 1934 he has been dealing with the extraction of iodine from algae using unique devices he himself invented and designed. Florensky considered iodine a very effective medicine that could cure many diseases, and, for example, used an alcohol solution of iodine to prevent influenza , adding 3-4 drops of it to milk.