What is iodine. Iodine
When iodine is mentioned, most of us think of a small vial and a cotton swab. This is how our mothers treated scratches and abrasions in childhood. And today you can find such iodine, the price in a pharmacy for it is cheap.
Many adults know that iodine is a very important trace element. It affects the functioning of the thyroid gland and is involved in the metabolic process. Iodine-containing drugs will have a price an order of magnitude higher than a vial for treating wounds. What is iodine made from? And why is the price so different?
What is iodine?
Iodine is a mineral that is found in inorganic compounds: water, soil, after rain it can be found in the air. It is also present in many plant and animal foods. So, it is well known that there is a lot of iodine in kelp, as well as other seafood: fish, shellfish, crustaceans.
Iodine is also found in common foods that are well known to us: eggs, beef, milk, butter, ordinary cabbage, other vegetables, and cereals. The problem is that they don't have enough of it. So, for example, cod liver (it is believed that it has a lot of iodine) contains 800 micrograms of the mineral, and in order to satisfy the daily requirement, you need to eat 180 g of this product daily.
When deciding what is better - brilliant green or iodine, we do not think about how important iodine is in a person's daily life.
An adult needs 150 micrograms of iodine per day, and pregnant women need 200 micrograms. The norm for infants is 50 micrograms, and for a student - 120 micrograms.
Another problem associated with the delivery of this substance to the human body will be its destruction during the preparation process. So, during cooking, about 50% of this useful substance is lost. A pack in a month will contain only 50% of the declared amount.
Growing plants on soils that are poor in the mineral will significantly reduce its amount in the respective food products.
Here, the solution to the problem can be called a medical price in a pharmacy for them, but often far from publicly available.
Medical uses of iodine
Why is this mineral, found in very small amounts in the human body, so important to us?
It is only about 25 milligrams, but it plays a very important role in metabolic processes. So, about 15 mg of iodine is in the thyroid gland and is part of the hormones triiodothyronine and thyroxine formed by it. These hormones are responsible for many functions:
- have a stimulating effect on the growth and development of the body as a whole;
- regulate energy and heat exchange;
- participate in the oxidation of carbohydrates, fats and proteins;
- accelerate the process of cholesterol breakdown;
- without them, the regulation of cardiac activity is not complete;
- they interfere with the process of blood clotting and the formation of blood clots;
- they are very important for the development of the central nervous system.
The remaining 10 mg were located in the reproductive organs of the ovaries (in women) and the prostate gland (in men), kidneys, liver, hair and nails.
The lack of this substance in the body of a child can cause a delay in his physical and mental development, and its excess will lead to poisoning called "iodism", possibly to disruption of the thyroid gland, a formidable disease called "hyperthyroidism".
For different purposes, the pharmacological industry produces different drugs. Today, medicines containing easily digestible iodine are expensive. And this is due not only to the technological process of manufacturing the drug, but also to the fact that the extraction of iodine itself is technologically complex and financially costly.
Many people are interested in the simple question of which is better - brilliant green or iodine when treating fresh wounds? It should be remembered here that iodine will not only prevent the development of the fungus and destroy the infection, Zelenka also copes well with this. It will promote faster healing of the wound - and in this case, iodine is more preferable.
Industrial use of the mineral
Iodine is important not only for ensuring the normal life cycle of a person, it is used in many industries, it is needed for the production of a large number of products.
So, with the participation of this substance, X-ray images are taken, photographs are taken, added to bearing oil, glasses for headlights and lamps with special effects are produced with its participation, it is needed to obtain high-purity metals.
Today, a new direction is developing in the production of incandescent lamps, where iodine plays an important role. Its use will significantly extend the life of conventional incandescent lamps with a tungsten filament.
According to statistics, 99% of known iodine reserves are located in Japan and Chile, they are the main suppliers of it to the world market. Thus, Chilean companies produce over 720 tons of iodine per year.
The production capacities of Russia allow producing up to 200 tons of raw mineral per year, which is 6 times less than the country's needs.
Extraction of iodine from seaweed
The question of the need for industrial extraction of this substance arose in the 18th century. Even then, it was noticed that marine plants have an increased content of this important mineral. The first industrial production was the extraction of iodine from seaweed. In Russia, such a plant was built in Yekaterinburg (1915), it produced a mineral from phylloflora (Black Sea algae).
Today, the extraction of this raw mineral from algae is the most common method for obtaining iodine on an industrial scale. Production is built near the sea, during the process they are extracted from the ashes of a dried sea plant. The largest enterprises extract up to 300 tons of crystalline mineral per year.
Sea kelp is classified as the main source of industrial production of iodine. It contains 0.8-0.16% iodine (in dry matter).
Isolation of the mineral from saltpeter waste
Isolation of iodine from mother brines of saltpeter production is one of the cheapest industrial methods. Here, to the question of what iodine is made of, the answer will be simple - from waste.
It was found that during the production or sodium) in the remains up to 4 g of iodate and sodium iodide for every 1 kg of brine (this is 0.4%). The method has been used for more than 200 years all over the world, its main advantage is its cheapness.
Obtaining iodine from brines
Another answer to the question of what iodine is made of will be the extraction of the mineral from natural inorganic raw materials - natural brines.
The fact is that when drilling oil wells in the associated waters, a significant amount of iodine was found, sometimes more than 100 micrograms per 1 liter, but mostly not more than 40. Potylitsyn A.L. (Russian chemist) discovered this feature of deep waters in 1882, however, extracting the mineral from brines was expensive and uneconomical.
Industrial extraction began only in Soviet times after the coal method of iodine accumulation was invented (1930). Coal is able to accumulate up to 40 g of iodine per 1 kg per month. Now it is one of the main methods of raw crystal mining in Russia.
Ionite mining
This technique is very widely used in Japan. The method is new and has been widely used only in recent decades. Here, high-molecular ion-exchange resins are used to extract the raw material.
However, in Russia it is not used, since it does not make it possible to extract all the iodine from the raw materials and leaves a significant amount of it in the waste.
Innovative methods of V. Ganyaev
Recently, Professor V. Ganyaev developed a unique technology for extracting iodine from mineral water. In the summer of 2016, a special installation was created, and today it is being successfully tested.
According to scientists, the new technology is not only environmentally cleaner, but also more economically advantageous; chloride compounds and sulfuric acid brines are not used here. When using it, the amount of extracted raw mineral will be 24 g per 1 liter of concentrate.
So to the question of what iodine is made of, you can also answer that in Russia - from mineral water. Although scientists believe that this technology will make it possible to use brines associated with oil production much more efficiently.
How is medical iodine produced?
Today, a well-known antiseptic, alcoholic 5% iodine, is being used less and less. It was replaced by drugs where iodine is used in conjunction with starch.
If we consider the question of whether there is a difference in the production of technical and medical iodine, then we should pay attention to the following.
- In the production of raw material on an industrial scale, it is produced in the form of a crystalline mineral with a certain content of pure iodine (according to the periodic table).
- Medical iodine becomes such after the combination of raw crystals with other substances: water, alcohols, ethers.
Hence the conclusion: initially, iodine crystals are not divided into medical and technical ones - they receive this status in the process of further processing.
The price of iodine preparations in pharmacies does not depend on the main component, but on those additional components that will be included in the medicine. In the well-known antiseptic vial, there is only iodine and ethyl alcohol, while, for example, drugs for the treatment of hyperthyroidism will be 2 orders of magnitude more expensive. They contain many other components.
History of iodine
The discovery of iodine dates back to 1811, the element was discovered by the Frenchman Bernard Courtois, who at one time was a specialist in soap and saltpeter making. One day, while experimenting with seaweed ash, a chemist noticed that a copper cauldron for evaporating ash is subject to rapid destruction. When ash vapors were mixed with sulfuric acid, vapors of a saturated violet color were formed, which, when precipitated, turned into shiny crystals of a dark “gasoline” color.
Two years later, Joseph Gay-Lussac and Humphry Davy began to study the resulting substance and named it iodine (from the Greek iodes, ioeides - violet, violet).
Iodine is a halogen, belongs to the reactive non-metals, an element of the 17th group of the V period of the periodic table of chemical elements D.I. Mendeleev, has atomic number 53, the accepted designation is I (Iodum).
Being in nature
Iodine is a rather rare element, but, oddly enough, it is present in nature almost everywhere, in any living organism, in sea water, soil, plant and animal products. Traditionally, seaweed provides the largest amount of natural iodine.
Physical and chemical properties
Iodine is a solid substance, in the form of crystals of dark purple or black-gray color, has a metallic luster and a specific smell. Vapors of iodine - violet, are formed when the microelement is heated, and when it is cooled, they turn into crystals without becoming liquid. To obtain liquid iodine, it must be heated under pressure.
Daily requirement for iodine
For the normal functioning of the thyroid gland, an adult needs 150-200 micrograms of iodine, adolescents, pregnant women and nursing mothers need to increase the amount of iodine entering the body daily to 400 micrograms per day.
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It must be remembered that during cooking, up to half of the amount of iodine is lost, as well as during long-term storage.
Useful properties of iodine and its effect on the body
Iodine is an active participant in oxidative processes that directly affect the stimulation of brain activity. Most of the iodine in the human body is concentrated in the thyroid gland and plasma. Iodine contributes to the neutralization of unstable microbes, thereby reducing irritability and stress (calorizator). Also, iodine has the property to increase the elasticity of the walls of blood vessels.
Iodine will facilitate dieting by burning excess fat, promote proper growth, give more energy, improve mental alertness, make hair, nails, skin and teeth healthy.
Signs of iodine deficiency
Lack of iodine is usually observed in regions where there is not enough natural trace elements. Signs of iodine deficiency are increased fatigue and general weakness, frequent headaches, weight gain, noticeable memory impairment, as well as vision and hearing, conjunctivitis, dry mucous membranes and skin. Lack of iodine leads to disruption of the menstrual cycle in women and a decrease in sexual desire and activity of the male.
Signs of excess iodine
An excess of iodine is no less harmful than its deficiency. Iodine is a toxic trace element, and when working with it, you need to be extremely careful to avoid poisoning, which is characterized by severe pain in the stomach, vomiting and diarrhea. With an excess of iodine in the water, the following symptoms are noted: an allergic rash and rhinitis, increased sweating with a pungent odor, insomnia, increased salivation and swelling of the mucous membranes, tremors, and rapid heartbeat. The most common disease associated with an increased amount of iodine in the body is Graves' disease.
The use of iodine in life
Iodine is mainly used in medicine, in the form of an alcohol solution - to disinfect the skin, speed up the healing of wounds and injuries, and also as an anti-inflammatory agent (an iodine cell is drawn at the site of bruises or during a cough for warmth). With a diluted solution of iodine, gargle with colds.
Iodine has found application in forensics (fingerprints are detected with it), as a component for light sources, and in the production of batteries.
Since childhood, a well-known helper for scratches, abrasions and cuts to all children and their parents. It is a fast and effective agent that cauterizes and disinfects the wound surface. However, the scope of the substance is not limited to medicine, because the chemical properties of iodine are very diverse. The purpose of our article is to get to know them in more detail.
Physical characteristic
A simple substance has the appearance of dark purple crystals. When heated, due to the peculiarities of the internal structure of the crystal lattice, namely the presence of molecules in its nodes, the compound does not melt, but immediately forms vapors. This is sublimation or sublimation. It is explained by a weak bond between the molecules inside the crystal, which are easily separated from each other - a gaseous phase of the substance is formed. The number of iodine in the periodic table is 53. And its position among other chemical elements indicates that it belongs to non-metals. Let's dwell on this issue further.
Place of an element in the periodic system
Iodine is in the fifth period, group VII, and, along with fluorine, chlorine, bromine and astatine, forms a subgroup of halogens. Due to the increase in the nuclear charge and atomic radius, the representatives of halogens have a weakening of non-metallic properties, therefore iodine is less active than chlorine or bromine, and its electronegativity is also lower. The atomic mass of iodine is 126.9045. A simple substance is represented by diatomic molecules, like other halogens. Below we will get acquainted with the structure of the atom of the element.
Features of the electronic formula
Five energy levels and the last of them almost completely filled with electrons confirm that the element has pronounced signs of non-metals. Like other halogens, iodine is a strong oxidizing agent, taking away from metals and weaker non-metallic elements - sulfur, carbon, nitrogen - the electron missing before the completion of the fifth level.
Iodine is a non-metal, in the molecules of which there is a common pair of p-electrons that binds atoms together. Their density at the place of overlap is the highest, the common electron cloud does not move to any of the atoms and is located in the center of the molecule. A non-polar covalent bond is formed, and the molecule itself has a linear shape. In the halogen series, from fluorine to astatine, the strength of the covalent bond decreases. There is a decrease in the enthalpy value, on which the decay of element molecules into atoms depends. What consequences does this have for the chemical properties of iodine?
Why is iodine less active than other halogens?
The reactivity of non-metals is determined by the force of attraction to the nucleus of their own atom of foreign electrons. The smaller the radius of an atom, the higher the electrostatic attraction forces of its negatively charged particles of other atoms. The higher the number of the period in which the element is located, the more energy levels it will have. Iodine is in the fifth period, and it has more energy layers than bromine, chlorine and fluorine. That is why the iodine molecule contains atoms that have a radius much larger than that of the previously listed halogens. That is why I 2 particles attract electrons weaker, which leads to a weakening of their non-metallic properties. The internal structure of a substance inevitably affects its physical characteristics. Let's give specific examples.
sublimation and solubility
A decrease in the mutual attraction of iodine atoms in its molecule leads, as we said earlier, to a weakening of the strength of the covalent nonpolar bond. There is a decrease in the resistance of the compound to high temperature and an increase in the thermal dissociation of its molecules. A distinctive feature of halogen: the transition of a substance when heated from a solid state immediately to a gaseous state, i.e. sublimation is the main physical characteristic of iodine. Its solubility in organic solvents, such as carbon disulfide, benzene, ethanol, is higher than in water. So, in 100 g of water at 20 ° C, only 0.02 g of a substance can dissolve. This feature is used in the laboratory to extract iodine from an aqueous solution. Shaking it with a small amount of H 2 S, one can observe a violet coloration of hydrogen sulfide due to the transition of halogen molecules into it.
Chemical properties of iodine
When interacting with metals, the element always behaves in the same way. It attracts the valence electrons of the metal atom, which are located either on the last energy layer (s-elements, such as sodium, calcium, lithium, etc.), or on the penultimate layer containing, for example, d-electrons. These include iron, manganese, copper and others. In these reactions, the metal will be the reducing agent, and iodine, whose chemical formula is I 2, will be the oxidizing agent. Therefore, it is this high activity of a simple substance that is the reason for its interaction with many metals.
Noteworthy is the interaction of iodine with water when heated. In an alkaline medium, the reaction proceeds with the formation of a mixture of iodide and iodic acids. The latter substance exhibits the properties of a strong acid and, upon dehydration, turns into iodine pentoxide. If the solution is acidified, then the above reaction products interact with each other to form the initial substances - free I 2 molecules and water. This reaction belongs to the redox type, it manifests the chemical properties of iodine as a strong oxidizing agent.
Qualitative reaction to starch
In both inorganic and organic chemistry, there is a group of reactions that can be used to identify certain types of simple or complex ions in the interaction products. To detect macromolecules of a complex carbohydrate - starch - a 5% alcohol solution of I 2 is often used. For example, a few drops of it are dripped onto a slice of a raw potato, and the color of the solution becomes blue. We observe the same effect when a substance enters any starch-containing product. This reaction, which produces blue iodine, is widely used in organic chemistry to confirm the presence of a polymer in a test mixture.
The beneficial properties of the product of the interaction of iodine and starch have long been known. It was used in the absence of antimicrobial drugs for the treatment of diarrhea, gastric ulcers in remission, diseases of the respiratory system. Starch paste, containing about 1 teaspoon of an alcohol solution of iodine per 200 ml of water, was widely used due to the cheapness of the ingredients and ease of preparation.
However, it must be remembered that blue iodine is contraindicated in the treatment of young children, people suffering from hypersensitivity to iodine-containing drugs, as well as patients with Graves' disease.
How non-metals react with each other
Among the elements of the main subgroup of group VII, iodine reacts with fluorine, the most active non-metal with the highest degree of oxidation. The process takes place in the cold and is accompanied by an explosion. With hydrogen, I 2 interacts with strong heating, and not completely, the reaction product - HI - begins to decompose into the starting substances. Hydroiodic acid is quite strong and although similar in characteristics to hydrochloric acid, it still shows more pronounced signs of a reducing agent. As you can see, the chemical properties of iodine are due to its belonging to active non-metals, however, the element is inferior in oxidizing ability to bromine, chlorine and, of course, fluorine.
The role of the element in living organisms
The highest content of ions I - is in the tissues of the thyroid gland, where they are part of the thyroid-stimulating hormones: thyroxine and triiodothyronine. They regulate the growth and development of bone tissue, the conduction of nerve impulses, and the metabolic rate. Especially dangerous is the lack of iodine-containing hormones in childhood, since mental retardation and the appearance of symptoms of a disease such as cretinism are possible.
Insufficient thyroxine secretion in adults is associated with water and food. It is accompanied by hair loss, the formation of edema, and a decrease in physical activity. An excess of an element in the body is also extremely dangerous, as Graves' disease develops, the symptoms of which are excitability of the nervous system, tremor of the limbs, and severe emaciation.
Distribution of iodides in nature and methods for obtaining a pure substance
The bulk of the element is present in living organisms and the Earth's shells - the hydrosphere and lithosphere - in a bound state. There are salts of the element in sea water, but their concentration is insignificant, therefore it is unprofitable to extract pure iodine from it. It is much more efficient to obtain a substance from the ashes of brown sargassum.
On an industrial scale, I 2 is isolated from groundwater in oil production processes. During the processing of some ores, for example, potassium iodates and hypoiodates are found in it, from which pure iodine is subsequently extracted. It is quite cost-effective to obtain I 2 from a solution of hydrogen iodine, oxidizing it with chlorine. The resulting compound is an important raw material for the pharmaceutical industry.
In addition to the already mentioned 5% alcohol solution of iodine, which contains not only a simple substance, but also a salt - potassium iodide, as well as alcohol and water, in endocrinology, for medical reasons, drugs such as "Iodine-active" and "Iodomarin" are used.
In areas with a low content of natural compounds, in addition to iodized table salt, you can use a remedy such as Antistrumine. It contains the active substance - potassium iodide - and is recommended as a prophylactic drug used to prevent the symptoms of endemic goiter.
Iodine (a trivial (common) name is iodine; from other Greek ἰώδης - “violet (violet)”) - an element of the 17th group of the periodic table of chemical elements (according to the outdated classification - an element of the main subgroup of group VII), the fifth period, with atomic number 53. Denoted by the symbol I (lat. Iodum). Reactive non-metal, belongs to the group of halogens.
The simple substance iodine (CAS number: 7553-56-2) under normal conditions is black-gray crystals with a violet metallic luster, easily forms violet vapors with a pungent odor. The molecule of a substance is diatomic (formula I 2).
Story
iodine was discovered in 1811 by Courtois in the ashes of seaweed, and from 1815 Gay-Lussac began to consider it as a chemical element.
Name and designation
The name of the element was proposed by Gay-Lussac and comes from other Greek. ἰώδης, ιώο-ειδης (lit. "violet-like"), which is associated with the color of the steam, which was observed by the French chemist Bernard Courtois, heating the mother brine of seaweed ash with concentrated sulfuric acid. In medicine and biology, this element and simple substance is usually called iodine, for example, “iodine solution”, in accordance with the old version of the name that existed in chemical nomenclature until the middle of the 20th century.
In modern chemical nomenclature, the name iodine is used. The same position exists in some other languages, for example in German: the common Jod and the terminologically correct Iod. Simultaneously with the change in the name of the element in the 1950s by the International Union of General and Applied Chemistry, the element symbol J was changed to I.
Physical properties
iodine under normal conditions is a solid black-gray substance with a metallic luster and a specific odor. Vapors have a characteristic violet color, just like solutions in non-polar organic solvents, such as benzene, in contrast to a brown solution in polar alcohol. iodine at room temperature is a dark purple crystals with a faint luster. When heated at atmospheric pressure, it sublimates (sublimates), turning into a violet vapor; when cooled, iodine vapor crystallizes, bypassing the liquid state. This is used in practice to purify iodine from non-volatile impurities.
Chemical properties
Iodine belongs to the group of halogens.
It forms a number of acids: hydroiodic (HI), iodic (HIO), iodide (HIO 2), iodic (HIO 3), iodine (HIO 4).
Chemically, iodine is quite active, although to a lesser extent than chlorine and bromine.
1. With light heating, iodine interacts vigorously with metals, forming iodides:
Hg + I 2 = HgI 2
2. Iodine reacts with hydrogen only when heated and not completely, forming hydrogen iodine:
I 2 + H 2 \u003d 2HI
3. Atomic iodine is an oxidizing agent, less powerful than chlorine and bromine. Hydrogen sulfide H 2 S, Na 2 S 2 O 3 and other reducing agents reduce it to the I ion -:
I 2 + H 2 S \u003d S + 2HI
4. When dissolved in water, iodine partially reacts with it:
I 2 + H 2 O ↔ HI + HIO, pK c \u003d 15.99