Sodium thiosulfate structural formula. Sodium thiosulfate (Sodium thiosulfate)
Sodium thiosulfate is a synthetic compound known in chemistry as sodium sulphate, and in the food industry as additive E539, approved for use in food production.
Sodium thiosulfate acts as an acidity regulator (antioxidant), anti-caking agent or preservative. The use of thiosulfate as a food additive allows you to increase the shelf life and product quality, prevent rotting, souring, fermentation. In its pure form, this substance is involved in the technological processes for the manufacture of food iodized salt as an iodine stabilizer and is used to process bakery flour, which is prone to caking and clumping.
The use of food additive E539 is limited exclusively to the industrial sector, the substance is not available for retail sale. For medical purposes, sodium thiosulfate is used as an antidote for severe poisoning and as an external anti-inflammatory agent.
general information
Thiosulfate (hyposulfite) is an inorganic compound that is the sodium salt of thiosulfuric acid. The substance is a colorless, odorless powder, which on closer examination turns out to be transparent monoclinic crystals.
Hyposulfite is an unstable compound that does not occur naturally. The substance forms a crystalline hydrate, which, when heated above 40 ° C, melts in its own crystalline water and dissolves. Molten sodium thiosulfate is prone to supercooling, and at a temperature of about 220 ° C, the compound is completely destroyed.
Sodium thiosulfate: synthesis
Sodium sulphate was first obtained artificially in the laboratory by the Leblanc method. This compound is a by-product of soda production that results from the oxidation of calcium sulfide. Interacting with oxygen, calcium sulfide is partially oxidized to thiosulfate, from which Na 2 S 2 O 3 is obtained using sodium sulfate.
Modern chemistry offers several ways to synthesize sodium sulphate:
- oxidation of sodium sulfides;
- boiling sulfur with sodium sulfite;
- interaction of hydrogen sulfide and sulfur oxide with sodium hydroxide;
- boiling sulfur with sodium hydroxide.
The above methods make it possible to obtain sodium thiosulfate as a by-product of the reaction or as an aqueous solution from which the liquid must be evaporated. You can get an alkaline solution of sodium sulphate by dissolving its sulfide in oxygenated water.
The pure anhydrous compound of thiosulfate is the result of the reaction of the sodium salt of nitrous acid with sulfur in a substance known as formamide. The synthesis reaction proceeds at a temperature of 80 ° C and lasts about half an hour, its products are thiosulfate and its oxide.
In all chemical reactions, hyposulfite manifests itself as a strong reducing agent. In interaction reactions with strong oxidizing agents, Na 2 S 2 O 3 is oxidized to sulfate or sulfuric acid, with weak oxidants to a tetrathione salt. The oxidation reaction of thiosulfate is the basis of the iodometric method for determining substances.
Special attention deserves the interaction of sodium thiosulfate with free chlorine, which is a strong oxidizing agent and a toxic substance. Hyposulfite is easily oxidized by chlorine and converts it into harmless water-soluble compounds. Thus, this compound prevents the destructive and toxic effects of chlorine.
Under industrial conditions, thiosulfate is extracted from gas production waste. The most common raw material is lighting gas, which is released during coal coking and contains impurities of hydrogen sulfide. Calcium sulfide is synthesized from it, which is subjected to hydrolysis and oxidation, after which it is combined with sodium sulfate to obtain thiosulfate. Despite the multi-stage nature, this method is considered the most cost-effective and environmentally friendly method for extracting hyposulfite.
| Systematic name | Sodium thiosulfate (Sodium thiosulfate) |
|---|---|
| Traditional Appellations | Sodium sulfate, hyposulfite (sodium) soda, antichlor |
| International marking | E539 |
| Chemical formula | Na 2 S 2 O 3 |
| Group | Inorganic thiosulfates (salts) |
| State of aggregation | Colorless monoclinic crystals (powder) |
| Solubility | Soluble in, insoluble in |
| Melting temperature | 50 °C |
| Critical temperature | 220 °С |
| Properties | Reducing (antioxidant), complexing |
| Dietary Supplement Category | Acidity regulators, anti-caking agents (anti-caking agents) |
| Origin | Synthetic |
| Toxicity | Not tested, the substance is conditionally safe |
| Areas of use | Food, textile, leather industry, photography, pharmaceuticals, analytical chemistry |
Sodium thiosulfate: application
Sodium sulphate has been used for a variety of purposes long before its inclusion in food supplements and medicines. Antichlor was impregnated with gauze bandages and filters of gas masks to protect the respiratory organs from poisonous chlorine during the First World War.
Modern areas of application of hyposulfite in industry:
- film processing and fixing images on photographic paper;
- dechlorination and bacteriological analysis of drinking water;
- removal of chlorine stains when bleaching fabrics;
- leaching of gold ore;
- production of copper alloys and patina;
- skin tanning.
Sodium sulphate is used as a reagent in analytical and organic chemistry, it neutralizes strong acids, neutralizes heavy metals and their toxic compounds. The interaction reactions of thiosulfate with various substances are the basis of iodometry and bromometry.
Food supplement E539
Sodium thiosulfate is not a widely used food additive and is not freely available due to the instability of the compound and the toxicity of its degradation products. Hyposulfite is involved in technological processes for the production of food iodized salt and bakery products as an acidity regulator and anti-caking agent (anti-caking agent).
Additive E539 performs the functions of an antioxidant and preservative in the manufacture of canned vegetables and fish, desserts and alcoholic beverages. This substance is also part of the chemicals that treat the surface of fresh, dried and frozen vegetables and fruits.
The preservative and antioxidant E539 is used to improve the quality and increase the shelf life of such products:
- fresh and frozen vegetables, fruits, seafood;
- , nuts, seeds;
- vegetables, mushrooms and seaweed preserved in or oil;
- jams, jellies, candied fruits, fruit purees and fillings;
- fresh, frozen, smoked and dried fish, seafood, canned food;
- flour, starches, sauces, seasonings, vinegar, ;
- white and cane, sweeteners (dextrose and), sugar syrups;
- fruit and vegetable juices, soft drinks, soft drinks, grape juices.
In the manufacture of table iodized salt, the food additive E539 is used to stabilize iodine, which can significantly extend the shelf life of the product and preserve its nutritional value. The maximum allowable concentration of E539 in table salt is 250 mg per 1 kg.
In the baking business, sodium thiosulfate is actively used as part of various additives to improve product quality. Bread improvers are oxidative and reductive. Anti-caking agent E539 refers to improvers of restorative action that allow you to change the properties.
Dough made from dense flour with short-tearing gluten is difficult to process, cakes, does not reach the required volume and cracks during baking. The anti-caking agent E539 destroys disulfide bonds and structures gluten proteins, as a result of which the dough rises well, the crumb becomes loose and elastic, and the crust does not crack when baking.
At enterprises, an anti-caking agent is added to flour along with yeast immediately before dough is kneaded. The content of thiosulfate in flour is 0.001-0.002% of its mass, depending on the technology of manufacturing a bakery product. Sanitary and hygienic standards for the additive E539 are 50 mg per 1 kg of wheat flour.
Anti-caking agent E539 is used in technological processes in a strict dosage, so there is no risk of thiosulfate poisoning when using flour products. Flour intended for retail sale is not processed before sale. Within the normal range, the supplement is safe and does not have a toxic effect on the body.
Use in medicine and its effect on the body
Soda hyposulfite is included in the list of essential medicines of the World Health Organization as one of the most effective and safe medicines. It is injected under the skin, intramuscularly and intravenously as an injection or used as an external agent.
In the early twentieth century, sodium thiosulfate was first used as an antidote for hydrocyanic acid poisoning. In combination with sodium nitrite, thiosulfate is recommended for particularly severe cases of cyanide poisoning and is administered intravenously to convert cyanide to non-toxic thiocyanates that can then be safely excreted from the body.
Medical use of sodium sulphate:
The effect of hyposulfite on the human body when taken orally has not been studied, therefore it is impossible to judge the benefits and harms of the substance in its pure form or as part of food. There have been no cases of poisoning with the E539 additive, so it is considered to be non-toxic.
Sodium thiosulfate and legislation
Sodium thiosulfate is included in the list of food additives approved for use in the manufacture of food products in Russia and Ukraine. Anti-caking agent and acidity regulator E539 are used in accordance with established sanitary and hygienic standards exclusively for industrial purposes.
Due to the fact that the effect of the chemical on the human body when administered orally has not yet been studied, the E539 supplement is not approved for use in the EU and the USA.
In medical practice in the form of a solution for injections as a detoxifying and desensitizing agent or externally as an insecticidal agent, in veterinary medicine as a remedy for skin diseases, in the pharmaceutical industry in the manufacture of medicines; for the preparation of solutions of sodium thiosulfate 30% for injection.Sodium thiosulfate is also used
- for removing traces of chlorine after bleaching fabrics
- for the extraction of silver from ores;
- fixer in photography;
- reagent in iodometry
- antidote for poisoning: As, Br, Hg and other heavy metals, cyanides (translates them into thiocyanates), etc.
- for intestinal disinfection;
- for the treatment of scabies (together with hydrochloric acid);
- anti-inflammatory and anti-burn agent;
- can be used as a medium for determining molecular weights by freezing point depression (cryoscopic constant 4.26°)
- registered in the food industry as food additive E539.
- additives for concrete.
- for cleansing tissues from iodine
Description
Physiochemical properties
Colorless transparent crystals, odorlessPacking
Bag 40 kg. Package 1 kg. Bag 35 kg. Bag 0.5 kg. Bag 1 kg. Bag 5 kg. Bag 10 kg.
Storage
Packaging: 0.5 kg; 1 kg; 5 kg; 10 kg; 35 kg; 40 kg; 45 kg in packages or bags made of polyethylene film or packaging paper with a polymer coating.
Storage: In a dry place, in a well-packed container. Shelf life - 5 years.
Sodium thiosulfate pharmacopoeial production of the Chemical Plant. L.Ya. Karpov
| Mass fraction, % | Norm | |
|---|---|---|
| Na 2 S 2 O 3 * 5H 2 O | 99,0-102,0 | |
| calcium | lack of response | |
| sulfides | you stand the test | |
| sulfites and sulfates | Max. | 0,01 |
| chlorides | Max. | 0,005 |
| heavy metals | Max. | 0,001 |
| arsenic, selenium | lack of response | |
| gland | Max. | 0,002 |
| alkalinity | lack of pink coloration of phenolphthalein | |
| Microbiological purity | complies with GF XI issue 2, p. 193 |
- Item Code: 264-01
- Availability: In stock
One ampoule with 10 ml of injection solution contains 3 g sodium thiosulfate .
Excipients: sodium bicarbonate and water for injection.
Release form
- sterile solution for intravenous administration 30%;
- 60% solution (used to treat scabies);
- powder.
pharmachologic effect
Pharmacodynamics and pharmacokinetics
Sodium thiosulfate - what is it?
Sodium thiosulfate is a salt of thiosulfuric acid and sodium, which is used as a drug antihistamine and detoxification action .
It forms compounds with cyanides, halogens, salts of heavy metals that are slightly toxic or completely harmless to the body. A solution of sodium thiosulfate has found application in medicine as an antidote against I, Hg, Cr, aniline, sublimate, benzene, hydrocyanic acid.
Formula sodium thiosulfate. - Na2SO3S or Na2S2O3.
Pharmacodynamics
In case of poisoning with Pb, Hg, As compounds, non-toxic sulfites are formed. In case of poisoning with hydrocyanic (hydrocyanic) acid and its salts, detoxification is carried out due to the utilization of cyanide.
The latter with the participation of the enzyme rhodonase , which exhibits maximum activity in the liver, is converted into a relatively non-toxic thiocyanate ion.
The organism itself is able to neutralize cyanides, however, natural purification occurs very slowly: the activity of the rhodonase system in case of cyanide poisoning is not enough for detoxification.
To stimulate the reaction catalyzed by rhodonase, exogenous sulfur donors (in particular, sodium thiosulfate) are introduced into the body.
Anti-scabies activity is due to the ability of sodium thiosulfate to decompose into sulfur dioxide and sulfur in an acidic environment. Both of these substances are detrimental to both adult scabies mites and their eggs.
Pharmacokinetics
After injection of the drug into a vein, sodium thiosulfate is distributed in the extracellular space, excreted from the body by the kidneys unchanged. Biological T1 / 2 - 0.65 hours.
The substance is non-toxic. Studies conducted on dogs have shown that with constant infusion of the drug, there is hypovolemia . The decrease in BCC is most likely due to the osmotic diuretic effect of the drug.
It is used in a complex of means to eliminate the consequences of poisoning in patients with alcoholic delirium .
Indications for use
As an antidote, the drug is used for intoxication with salts of I and Br, Pb, As, Hg, cyanides and hydrocyanic acid. It is also prescribed for lupus erythematosus, scabies, neuralgia, arthritis, and allergic diseases.
Contraindications
The only contraindication to cleansing the body with a remedy is hypersensitivity to its active substance.
Side effects
Hypersensitivity reactions. With the introduction of the drug intravenously, side effects can be expressed in the form of pain at the injection site.
Sodium thiosulfate: instructions for use
It is used externally, intravenously and orally.
External use is indicated for . According to the instructions for sodium thiosulfate, a 60% solution should be rubbed into the skin of the limbs and torso, and then, when it dries, moisten the treated surfaces with a 6% hydrochloric acid solution.
Sodium thiosulfate intravenously and orally is prescribed to cleanse the body during intoxication.
Sodium thiosulfate is administered intravenously as a 30% solution. The dose varies from 5 to 50 ml and depends on the severity of intoxication and the type of poisonous substance.
For oral administration, a 10% solution is used. A single dose is 2-3 grams of sodium thiosulfate.
Sodium thiosulfate in gynecology
In gynecological pathologies, the drug is used, as a rule, as an addition to the main treatment.
Sodium thiosulfate is used intravenously in gynecology as part of endocrine infertility treatment programs. In this case, the patient is also prescribed injections intramuscularly, plasmapheresis and transorbital electrophoresis of nicotinic acid.
To eliminate cysts in the ovaries for the remedy is used in combination with , and .
At genital tuberculosis it is included in non-specific therapy: the patient is prescribed enzyme preparations (or lidase ), antioxidants (vitamin E) and sodium thiosulfate. The latter is injected into a vein at 10 ml every other day or once or twice a day. For a course of treatment, a woman should receive from 40 to 50 infusions of the drug.
In some cases, sodium thiosulfate is used in the form of microclysters. Some doctors recommend this method of treatment for adhesive processes in the pelvis and inflammatory diseases of the reproductive system.
The procedure is carried out using a 10% solution. Single dose - 30-50 ml. Before introduction into the anus, the solution is heated to a temperature of 37-40ºC in a water bath. It should be remembered that this is not a cleansing enema, therefore, the drug must be completely absorbed into the body through the intestinal mucosa.
Reviews allow us to conclude that the use of the drug for as an anti-inflammatory and resolving agent, it is a good alternative to hormonal treatment.
An important property of the drug is the ability to prevent the development of allergic reactions that may occur during the complex treatment of certain female diseases.
The versatility of using sodium thiosulfate allows you to choose the most appropriate method of application in each case: in the form of microenemas, intravenously or during physiotherapy procedures (electrophoresis).
Sodium thiosulfate for psoriasis
You can check the authenticity of sodium thiosulfate by dropping it on it. As a result of a chemical reaction, the latter should discolor.
To verify the authenticity of sodium acetate, the substance is mixed with dry phenolphthalein and heated on a burner. As a result, sodium acetate will melt, phenolphthalein will turn red.
Analogues
Coincidence in the ATX code of the 4th level:Algisorb , ,Bridan , , dipyroxime , Carboxyme ,lobelin , , sodium nitrite , Pelixim , Pentacin , , Ferrocin , Amber-antitox .
Sodium thiosulfate intravenously and alcohol
One of the most effective ways to get rid of alcohol addiction is the so-called conditioned reflex therapy(conditioned reflex therapy). The treatment boils down to the fact that the patient is given drugs that, in combination with alcohol, cause a lot of unpleasant sensations: nausea, vomiting, hand tremors, coughing, heart rhythm disturbances, sweating, etc. As a result, a steady rejection of alcohol is formed.
However, most drugs that are used to treat alcoholism have contraindications, and their use is often accompanied by adverse reactions from the kidneys and liver.
In comparison with such agents, sodium thiosulfate is absolutely non-toxic. The only contraindication to its appointment is individual intolerance.
The drug contributes to the formation of negative reflexes to alcoholic beverages from the nervous system and gastrointestinal tract, but it does not cause any harm to the body.
It usually takes 16 to 20 days to kick a bad habit. Treatment is carried out on an outpatient basis daily.
Sodium thiosulfate is administered intravenously, the dose is selected individually. Immediately after the completion of the procedure, the patient is given to drink 20-30 g of vodka to monitor his reaction to alcohol intake.
As a rule, the first discomfort occurs after 2-3 days of treatment. Thus, a steady aversion to alcohol is gradually formed.
16-20 days after the start of the course, the number of injections is reduced to three times a week and then - gradually - to once a month.
Treatment with hyposulfite has no age restrictions. At the same time, in patients who have completed the full course of treatment, relapses are not observed. The drug is easily tolerated even by elderly people with various somatic diseases.
The use of the drug for weight loss
Supporters of cleansing the body at home with the help of sodium thiosulfate argue that the drug not only removes all the “dirt” accumulated in it from the body, but also helps to remove extra pounds.
Is it so? Most likely, the whole point here is not the cleansing effect, but the fact that the drug, when taken orally, acts like a regular laxative. And the question of the advisability of using laxatives for weight loss is quite controversial.
Most doctors provide convincing evidence that the problem of excess weight cannot be solved in this way. But the result of self-medication may well be dehydration, magnesium deficiency, chronic constipation, imbalance of water and electrolytes.
In general, weight loss, if possible, is only due to simple manipulation of the amount of water and intestinal contents. Sodium thiosulfate is simply not capable of removing body fat.
However, those who want to lose weight with the help of the drug are still there. The solution is taken by diluting the contents of the ampoule in 200 ml of water. Half the dose is drunk about an hour before breakfast, the rest - an hour before dinner or a couple of hours after it, at night. The course usually lasts 10-12 days.
If we analyze reviews of sodium thiosulfate, we can conclude that most of those who took it to lose weight did not notice any significant changes in the body: many note that they managed to lose 2 to 5 kg in a ten-day course.
The positive moments of cleansing are called the feeling of lightness that appears by 4-6 days, as well as the improvement in skin condition (some women claim that by the end of the course, their face was significantly cleared of acne).
During pregnancy
During pregnancy, the use is possible only in case of emergency. Studies of the effect of the drug on reproductive function in animals have not been conducted.
To date, it is not known whether sodium thiosulfate can cause adverse fetal effects when used in pregnant women. It is also not known whether the drug affects the ability to reproduce.
Thermally very unstable:
Decomposes in the presence of sulfuric acid:
Reacts with alkalis:
Reacts with halogens:
Thiosulfuric acid
If you boil an aqueous solution of sodium sulfite with sulfur and, after filtering out the excess sulfur, leave to cool, then colorless transparent crystals of a new substance stand out from the solution, the composition of which is expressed by the formula. This substance is the sodium salt of thiosulfuric acid.
Thiosulfuric acid is unstable. Already at room temperature, it decomposes. Much more stable than its salts are thiosulfates. Of these, sodium thiosulfate, also known by the incorrect name "hyposulfite", is the most commonly used.
When an acid, such as hydrochloric acid, is added to a solution of sodium thiosulfate, the smell of sulfur dioxide appears and after a while the liquid becomes cloudy from the released sulfur.
The study of the properties of sodium thiosulfate leads to the conclusion that the sulfur atoms that make up its composition have different oxidation states: one of them has an oxidation state of +4, the other has 0 . Sodium thiosulfate - reducing agent . Chlorine, bromine and other strong oxidizing agents oxidize it to sulfuric acid or to its salt.
thiosulfate?- salts and esters of thiosulfuric acid, H2S2O3. Thiosulfates are unstable, therefore they do not occur in nature. The most widely used are sodium thiosulfate and ammonium thiosulfate.
Structure. Structure of the thiosulfate ion
The thiosulfate ion is similar in structure to the sulfate ion. In tetrahedron 2−, the S-S bond (1.97A) is longer than the S-O bonds
Sodium thiosulfate can be attributed to rather unstable substances. Sodium thiosulfate decomposes when heated to 220°C: In the reaction of thermal decomposition of sodium thiosulfate, sodium polysulfide is obtained, which also further decomposes into sodium sulfide and elemental sulfur. Interaction with acids: it is impossible to isolate thiosulfuric acid (hydrogen thiosulfate) by the reaction of sodium thiosulfate with a strong acid, since it is unstable and immediately decomposes: Hydrochloric and nitric acids will enter into the same reaction. Decomposition is accompanied by excretion, which has an unpleasant odor.
Redox properties of sodium thiosulfate: due to the presence of sulfur atoms with an oxidation state of 0, the thiosulfate ion has reducing properties, for example, weak oxidizing agents (I2, Fe3 +) thiosulfate is oxidized to tetrathionate ion: In an alkaline environment, the oxidation of sodium thiosulfate with iodine can go to sulfate.
And stronger oxidizing agents oxidize it to the sulfate ion :
Strong reducing agents the ion is reduced to derivatives S2-: Depending on the conditions, sodium thiosulfate can exhibit both oxidizing and reducing properties.
Complexing properties of thiosulfates:
Thiosulfate ion is a strong complexing agent , used in photography to remove unreduced silver bromide from film: The S2O32 ion is coordinated through the sulfur atom by metals, so thiosulfate complexes are easily converted to the corresponding sulfides.
Application of sodium thiosulfate
Sodium thiosulfate is quite widely used both in everyday life and in industry. The main areas of application of sodium thiosulfate will be medicine, textile and mining industry, photography.
Sodium thiosulfate is used in the textile and paper industries to remove traces of chlorine after bleaching textiles and paper, and in the manufacture of leather it is used as a chromic acid reducing agent.
In the mining industry, sodium thiosulfate is used to extract silver from ores with a low silver concentration. Complex compounds of silver with thiosulfates are quite stable, in any case more stable than complex compounds with fluorine, chlorine, bromides, thiocyanates. Therefore, the isolation of silver in the form of a soluble complex compound of composition or is industrially advantageous. Work is underway on the use in the extraction of gold. But in this case, the instability constant of the complex compound is much higher and the complexes are less stable than the silver ones.
The first use of sodium thiosulfate was medicine. And until now, it has not lost its significance in medicine. True, other, more effective drugs have already been found to treat many diseases, so sodium thiosulfate has begun to be more widely used in veterinary medicine. Sodium thiosulfate in medicine is used as an antidote for poisoning with arsenic, mercury and other heavy metals, cyanides (translates them into thiocyanates):
As mentioned above, the thiosulfate ion creates stable complex compounds with many metals, among which there are many toxic heavy metals. Created complex compounds are of low toxicity and are excreted from the body. This feature of sodium thiosulfate is the basis of its use in toxicology and the treatment of poisoning.
Sodium thiosulfate is also used for intestinal disinfection in case of food poisoning, for the treatment of scabies (together with hydrochloric acid), as an anti-inflammatory and anti-burn agent.
Sodium thiosulfate is widely used in analytical chemistry because it is a reagent in iodometry. Iodometry is one of the methods for the quantitative determination of the concentrations of substances and a redox reaction with sodium thiosulfate is used to determine the concentration of iodine:
And the last fairly common use of sodium thiosulfate is its use as a fixer in photography. And although ordinary black and white photography has already given way to color and ordinary film is used quite rarely, in many ways inferior to digital image capture, there are quite a few places where photographic plates and film are still used. As an example, we can cite X-ray devices, both for medical use and industrial ones, scientific equipment, photo telescopes.
In order for us to get a photographic image, it is enough that about 25% of silver bromide in photographic film appears. And the rest of it remains in the film and retains its sensitivity to light. If the photographic film is exposed to light after development, then the undeveloped halogen silver that remains in it will be developed by the developer and the negative will darken. Even if all the developer is washed out, the negative will darken anyway due to the decomposition of the silver halide.
To preserve the image on the film, undeveloped halogen silver must be removed from it. For this, an image fixation process is used, during which silver halides are converted into soluble compounds and washed out of photographic film or photography. To fix the image and use sodium thiosulfate.
Depending on the concentration of sodium thiosulfate in solution, various compounds are formed. If the fixer solution contains a small amount of thiosulfate, then the reaction proceeds according to the equation:
The resulting silver thiosulfate is insoluble in water, so it is difficult to isolate it from the photolayer, it is rather unstable and decomposes with the release of sulfuric acid:
Silver sulfide blackens the image and cannot be removed from the photo layer.
If there is an excess of sodium thiosulfate in the solution, complex silver salts will be formed:
The resulting complex salt - sodium thiosulfate argentate is quite stable, but poorly soluble in water.
With a large excess of thiosulfates in solution, complex and well-soluble complex silver salts are formed:
These properties of sodium thiosulfate are the basis for its use as a fixative in photography.
Tetratnopoic acid belongs to the group of politically new acids. These are dibasic acids of the general formula, where it can take values from 2 to 6, and possibly more. Polythionic acids unstable and known only in aqueous solutions. Salts of polythioic acids - polythionates - are more stable; some of them are obtained in the form of crystals.
Polythionic acids - sulfur compounds with the general formula H2SnO6, where n>=2. Their salts are called polythionates.
tetrathionate ion can be obtained by oxidation of the thiosulfate ion with iodine (the reaction is used in iodometry):
Pentationate ion obtained by the action of SCl2 on the thiosulfate ion and from the Wakenroder liquid by adding potassium acetate to it. First, prismatic crystals of potassium tetrathionate precipitate, then lamellar crystals of potassium pentathionate, from which an aqueous solution of pentathionic acid is obtained by the action of tartaric acid.
Potassium hexathionate K2S6O6 best synthesized by the action of KNO2 on K2S2O3 in concentrated HCl at low temperatures.
2 3 or Na 2 SO 3 S, sodium salt and thiosulfuric acid, forms a crystalline Na 2 S 2 O 3 5H 2 O.
Receipt
- oxidation of polysulfides;
- boiling excess sulfur with Na 2 SO 3:
- the interaction of H 2 S and SO 2 with NaOH (a by-product in the production of NaHSO 3, sulfur dyes, in the purification of industrial gases from):
- boiling excess sulfur with sodium hydroxide:
then, according to the above reaction, sodium sulfite adds sulfur, forming sodium thiosulfate.
At the same time, during this reaction, sodium polysulfides are formed (they give the solution a yellow color). For their destruction, SO 2 is passed into the solution.
- pure anhydrous sodium thiosulfate can be obtained by reacting sulfur with sodium nitrite in formamide. This reaction proceeds quantitatively (at 80 °C in 30 minutes) according to the equation:
- dissolution of sodium sulfide in water in the presence of atmospheric oxygen:
Physical and chemical properties
Colorless monoclinic crystals. Molar mass 248.17 g/mol (pentahydrate).
Soluble in water (41.2% at 20°C, 69.86% at 80°C).
At 48.5 °C, the crystalline hydrate dissolves in its water of crystallization, forming a supersaturated solution; dehydrated at about 100°C.
When heated to 220 ° C, it decomposes according to the scheme:
Sodium thiosulfate is a strong reducing agent:
With strong oxidizing agents, such as free chlorine, it oxidizes to sulfates or sulfuric acid:
Weaker or slower acting oxidizing agents, such as iodine, are converted to salts of tetrathionic acid:
The above reaction is very important, as it serves as the basis of iodometry. It should be noted that in an alkaline medium, sodium thiosulfate can be oxidized with iodine to sulfate.
It is impossible to isolate thiosulfuric acid (hydrogen thiosulfate) by the reaction of sodium thiosulfate with a strong acid, since it is unstable and immediately decomposes into water, sulfur and sulfur dioxide:
Molten hydrated Na 2 S 2 O 3 ·5H 2 O is very prone to supercooling.
Application
- for removing traces of chlorine after bleaching fabrics
- to extract silver from ores;
- fixer in photography;
- reagent in iodometry
- antidote for poisoning:,, and other heavy metals, cyanides (translates them into thiocyanates), etc.
- for intestinal disinfection;
- for the treatment of scabies (together with hydrochloric acid);
- anti-inflammatory and anti-burn agent;
- can be used as a medium for determining molecular weights by freezing point depression (cryoscopic constant 4.26°)
- registered in the food industry as a food additive E539.
- additives for concrete.
- for cleansing tissues from iodine
- gauze bandages soaked in a solution of sodium thiosulfate were used to protect the respiratory organs from the poisonous substance chlorine in World War I.
- antidote for lidocaine overdose.
see also
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Links
- // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
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An excerpt describing sodium thiosulfate
In April, Rostov was on duty. At 8 o'clock in the morning, after returning home, after a sleepless night, he ordered to bring heat, changed his rain-soaked linen, prayed to God, drank tea, got warm, put things in order in his corner and on the table, and with a weathered, burning face, in one shirt, lay on his back, his hands under his head. He pleasantly thought about the fact that the next rank for the last reconnaissance should come to him the other day, and he was waiting for Denisov to come out somewhere. Rostov wanted to talk to him.Behind the hut, Denisov's rolling cry was heard, obviously getting excited. Rostov moved to the window to see who he was dealing with, and saw Sergeant Topcheenko.
“I told you not to let them burn this claw, some kind of Mashkin!” shouted Denisov.
“I ordered, your honor, they don’t listen,” the sergeant-major answered.
Rostov again lay down on his bed and thought with pleasure: “Let him now fuss, bustle, I finished my job and I’m lying - excellent!” From behind the wall he heard that, besides the sergeant-major, Lavrushka, Denisov's perky, roguish lackey, was also speaking. Lavrushka was talking about some kind of carts, crackers and bulls, which he saw when he went for provisions.
Behind the booth, Denisov's retreating cry was heard again and the words: “Saddle! Second squad!
"Where are they going?" thought Rostov.
Five minutes later Denisov entered the booth, climbed onto the bed with dirty feet, angrily smoked his pipe, scattered all his belongings, put on his whip and saber, and began to leave the dugout. To the question of Rostov, where? he answered angrily and vaguely that there was a case.
- Judge me there, God and the great sovereign! - said Denisov, leaving; and Rostov heard the feet of several horses splashing through the mud behind the booth. Rostov did not even bother to find out where Denisov had gone. Having warmed himself in his corner, he fell asleep, and before evening he had just left the booth. Denisov has not yet returned. Evening cleared up; near a neighboring dugout, two officers with a cadet were playing pile, laughingly planting radishes in the loose, dirty earth. Rostov joined them. In the middle of the game, the officers saw wagons approaching them: 15 hussars on thin horses followed them. The wagons escorted by the hussars drove up to the hitching posts, and a crowd of hussars surrounded them.
“Well, Denisov was grieve all the time,” said Rostov, “so the provisions have arrived.”
- And that! the officers said. - That's a happy soldier! - Denisov rode a little behind the hussars, accompanied by two infantry officers, with whom he was talking about something. Rostov went to meet him.
“I’m warning you, captain,” said one of the officers, thin, short and apparently angry.
“After all, he said that I wouldn’t give it back,” Denisov answered.
- You will answer, captain, this is a riot - to beat off transports from your own! We didn't eat for two days.
“But they didn’t eat mine for two weeks,” Denisov answered.
- This is robbery, answer, sir! – raising his voice, repeated the infantry officer.
- What are you doing to me? BUT? - shouted Denisov, suddenly heated up, - I will answer, not you, but you don’t buzz around here while you are safe. March! he shouted at the officers.
- It's good! - not shy and not driving away, the little officer shouted, - to rob, so I will ...
- To chog "that march with a quick step, while intact." And Denisov turned his horse to the officer.
“Good, good,” said the officer threateningly, and turning his horse, rode away at a trot, shaking in the saddle.
“A dog for godliness, a living dog for godliness,” Denisov said after him - the highest mockery of a cavalryman over a mounted infantryman, and, approaching Rostov, burst out laughing.
- Recaptured from the infantry, recaptured the transport by force! - he said. “Well, why don’t people die of hunger?”
The wagons that drove up to the hussars were assigned to an infantry regiment, but, having been informed through Lavrushka that this transport was coming alone, Denisov with the hussars recaptured it by force. The soldiers were handed out crackers at will, even shared with other squadrons.
The next day, the regimental commander called Denisov to him and told him, closing his eyes with open fingers: “I look at it like this, I don’t know anything and I won’t start business; but I advise you to go to the headquarters and there, in the food department, settle this matter, and, if possible, sign that you received so much food; otherwise, the demand is written to the infantry regiment: things will rise and may end badly.
Denisov went directly from the regimental commander to the headquarters, with a sincere desire to fulfill his advice. In the evening he returned to his dugout in a position in which Rostov had never seen his friend before. Denisov could not speak and was suffocating. When Rostov asked him what was the matter with him, he only uttered incomprehensible curses and threats in a hoarse and weak voice ...
Frightened by the position of Denisov, Rostov offered him to undress, drink water and sent for a doctor.
- To judge me for g "azboy - oh! Give me more water - let them judge, but I will, I will always beat the scoundrels, and I will tell the sovereign." Give me some ice, he said.
The regimental doctor who came said that it was necessary to bleed. A deep plate of black blood came out of Denisov's hairy hand, and then only he was able to tell everything that had happened to him.
“I’m coming,” Denisov said. “Well, where is your boss here?” Showed. Wouldn't you like to wait. “I have a service, I arrived 30 miles away, I have no time to wait, report back.” Well, this chief thief comes out: he also took it into his head to teach me: This is robbery! “Robbery, I say, is not done by the one who takes food to feed his soldiers, but by the one who takes it to put it in his pocket!” So you don't want to be silent. "Good". Sign, he says, with the commission agent, and your case will be handed over on command. I go to the commissioner. I enter - at the table ... Who is it ?! No, you think! ... Who is starving us, - Denisov shouted, hitting the table with his fist of his sore hand so hard that the table almost fell and the glasses jumped on it, - Telyanin !! “How are you starving us?!” Once, once in the face, deftly it had to be ... “Ah ... rasprotakoy and ... began to roll. On the other hand, I am amused, I can say, - Denisov shouted, joyfully and angrily baring his white teeth from under his black mustache. “I would have killed him if they hadn’t taken him away.”
