This is a natural organic compound found not only in plants, but also in the bodies of humans and animals.

Oxalic acid, being an important element for stimulating internal processes occurring in the body, is safe in small quantities and is easily excreted from the body.

However, being thermally processed, it turns into inorganic, forming compounds with calcium and its use becomes harmful. Performing a lot of positive functions, under special conditions, it provokes pathological processes.

What is oxalic acid

Oxalic acid or enthanedioic acid is a type of organic acid belonging to the carboxylic group and has the international name Oxalic Acid dihydrate. It is a colorless, odorless substance.

In nature, salts of this acid are most often found, called oxalates. They are present in plants, which use it to protect themselves from animals. In laboratory conditions they are synthesized from carbohydrates, alcohols and glycols. Refers to fairly strong acids. Salts of oxalic acid are called oxalates.

The chemical compound easily reacts with calcium. During heat treatment, its chemical properties change and then its compounds with calcium cannot be absorbed by the body, as well as removed from it in a timely manner, which leads to the deposition of salts. Some authors call such an acid inorganic, although this name is not entirely correct from a scientific point of view.

Benefits and harm to the body

With normal metabolism and in small quantities, it:

• improves the body's absorption of calcium,
• serves as a supplier of magnesium and iron.
• helps improve intestinal motility,
• has a beneficial effect on the muscles and nervous system.

Showing some bactericidal effect, it helps cope with intestinal infections, chlamydia and tuberculosis, activates the healing process for rhinitis and sinusitis, and relieves migraines.

There is evidence that ethanedioic acid helps with painful menstruation and menopause; for men it is useful for infertility and impotence.

Oxalic acid in food

Oxalic Acid dihydrate can be formed inside the body through chemical reactions or come from outside through food. It is most found in sour greens, vegetables and fruits, but is also found in nuts, cereals, tea, meat and even chocolate. The safe concentration is 50 mg. per 100 gr. product. The same figure is considered the upper limit of acceptable daily consumption.

What products contain: According to laboratory data from LabCorp, the following are the products that hold the record for the content of ethanedioic acid (the average content is indicated based on mg/100 g):

Sorrel, rhubarb and spinach considered the most abundant plant sources in terms of content, traces of acid are present in all organs of the plant, but the largest amount is still in the green leaves, up to 800 mg, with slight fluctuations.

Canned rhubarb contains up to 600 mg, and stewed rhubarb contains up to 860 mg. It is curious that during heat treatment the concentration of oxalates in the product increases.

Frozen spinach contains up to 600 mg of oxalates per 100 g of greens, and boiled greens contain up to 750 mg.

In beets the amount reaches 500 mg, and in its relative chard - 645 mg

• Sprouted wheat – 269
• Peanuts – 187
• Chocolate – 117
• Lemon and lime peel - 100
• Parsley – 100
• Leek – 89
• Oatmeal – 41

A large amount of the substance is contained in the carambola fruit and okra vegetable, which are exotic for our country. In smaller, but quite noticeable quantities, it can be found in:

• Fruits and berries: apples, bananas, strawberries, grapes, red and black currants, plums, pomegranates, raspberries, oranges, peaches.
• Vegetables: eggplant, celery, green peas, parsnips, asparagus, tomatoes, carrots, onions.
• Meat and fish: liver, sardines, bacon.
• Seasonings: ginger, black pepper, poppy seeds.
• Drinks: tea, coffee, lemonade, fruit juices.

Harm of oxalates or oxalic acid salts to the body

Not all oxalates enter the body through food. According to research, a person receives on average no more than 15% from the outside, provided proper nutrition.

Formation of oxalates in the body

Most of the salts of ethanedioic acid, up to 40%, are formed in the liver as a result of chemical processes. Oxalates are also a product of vitamin C metabolism. A small amount is synthesized in the intestine when intestinal bacteria interact with carbohydrates.

Magnesium and calcium oxalates have the peculiarity of poor dissolution in water, therefore, in the process of removing unnecessary substances from the body, they involuntarily accumulate in the renal pelvis. First in the form of sand, later they grow together into large concretions in the form of pebbles, growing to bizarre coral shapes.

They can accumulate in the brain, joints and lungs, and other organs. And their bizarre shapes with sharp crystal ends not only cause pain, but also disrupt the integrity of tissues and cells, causing inflammatory processes.

Factors affecting oxalic acid metabolism disorders

With moderate amounts in food and normal functioning of the body, part of the oxalic acid is absorbed, and the other part is excreted in the urine. But when there is excess intake, or when disturbances occur in metabolic processes, it begins to accumulate and cause harm.

Risk factors for salt accumulation, in addition to poor nutrition, include factors such as:

• diseases pyelonephritis and diabetes mellitus,
• increased weight and fluid deficiency,
• lack of magnesium and B vitamins,
• as well as alcohol abuse.

Nervous tension can also provoke its increased synthesis. Often, increased oxalate levels result from impaired fat absorption. In this case, fatty acids combine with calcium, and oxalic acid salts partially accumulate in the intestines in free form and partially penetrate through the mucous membrane into the kidneys.

Therefore, people who have problems absorbing fats need to limit their intake and at the same time increase their calcium intake. Healthy people, as a rule, do not encounter such a problem.

Another reason for increased oxalate concentrations in the body may be antibiotic treatment. According to scientists, this is due to a specific anaerobic bacterium living in the gastrointestinal tract. Which brings only benefits because it feeds on calcium oxalates, so scientists called it Oxalobacter Formigenes.

Its presence in the intestines reduces the formation of calcium stones by up to 70%. Since antibiotics suppress the microflora of the gastrointestinal tract, and this bacterium is no exception, its death leads to an increase in harmful salts in the body. And then oxalates are absorbed through the intestinal mucosa into the bloodstream and spread throughout the body, forming crystals in the organs.

There is confirmation that after treatment with antibiotics, the flora is restored up to 6 months.

Signs of high oxalate levels

One of the signs of increased levels of Oxalic Acid dihydrate in the body is a large amount of oxalates in the urine, called oxaluria. By forming insoluble crystalline compounds with calcium, the salts turn into kidney stones, which close the ducts and make urination difficult.

Another confirmed fact suggests that in patients with oxaluria, the beneficial bacterium Oxalobacter Formigenes is completely absent. Hence the problems.

Additional symptoms include pain in the side, back, or lower abdomen. Blood appears in the urine. This happens due to the fact that the formed crystals injure the lining of the urinary tract. Often these symptoms are accompanied by increased fatigue. In this case, correcting the diet may not be enough and drug treatment will be required.

In more severe cases, a burning sensation appears in the mouth and throat, heart problems occur, and it becomes difficult to breathe.

The effect of oxalates on the body

The greatest harm to the body is caused by Oxalic Acid dihydrate, which is formed in products after heat treatment. When combined with calcium, the acid forms a salt, which accumulates in the body, is deposited in the form of stones and impairs the absorption of microelements. People with kidney problems, arthritis, or gout should limit their consumption of even fresh foods rich in oxalic acid.

1. Products with a high content of oxalic acid should be consumed fresh if possible, without heat treatment. It is advisable to include in food young plants that have not had time to accumulate large amounts of oxalates.
2. As you have already noticed (this was discussed above), heat treatment increases the concentration of oxalates in products. If you need to add fresh leaves to a dish, first soak them in boiling water for about two minutes and pour out this water. That is, use cooking in two waters.
3. Drink plenty of water, don't forget about mineral water.
4. A good help is the use of citrates. It is no coincidence that for patients with urolithiasis, the doctor recommends taking potassium and sodium citrates, which reduce the formation of difficultly soluble calcium salts in the body. Citrates can be compensated for with lemon drinks with lemon juice; you should take up to 100 g of juice per day, adding it to water and tea.
5. People with a predisposition to salt deposition are prohibited from taking vitamin complexes containing vitamin C (ascorbic acid). Since an excess of this vitamin activates the process of accumulation of oxalic acid in the body.
6. Increase the content of foods rich in calcium and magnesium in your diet.
7. A low-calorie diet can be a preventative measure in reducing oxalate levels in the body.

Use of oxalic acid in everyday life

Ethanedioic acid is not citric acid, so a bag of it cannot be found on a supermarket shelf. It is sold mainly in chemical stores or chemical laboratories and is used in various types of industry.

It is included in cleaning and disinfectants because it bleaches and removes rust well.

As a whitening agent, cosmetologists add it to various creams and serums.

Widely used as an insecticide in agriculture. In the chemical industry it is used in the production of plastics and dyes. Tanners use it to tan leather. Some indoor plant lovers use it to soften water for watering.

Oxalic acid is a substance little known to most people. However, it has a significant impact on the functioning of the gastrointestinal tract, excretory and skeletal systems and on human health in general. Knowledge of where it is found and how much it can be consumed will be useful for everyone, especially for people prone to salt deposits.

Like any natural substance, Oxalic Acid dihydrate is useful in small quantities, and you should not be afraid to use it, the main thing is to observe moderation.

I wish you health, dear readers!

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Oxalic acid is an organic compound found in nature both in pure form and in the form of salts - oxalates. This substance was first discovered at the end of the 18th century during studies of sorrel salt. A few decades later (in 1824), the German scientist Friedrich Wöhler was able to synthesize it from cyanogen.

Today, the question remains open about the beneficial properties of this compound and its negative impact on the human body. It has been proven that uncontrolled consumption of food rich in oxalic acid provokes the development of kidney stones and other pathological processes. Along with this, this substance performs a lot of useful functions in the human body and protects its internal organs and systems from the adverse effects of endogenous and exogenous factors.

The benefits and harms of oxalic acid

Oxalic acid is an intermediate metabolic product, the excess of which is quickly eliminated from the body in the form of oxalates. This compound is not only absolutely harmless for a healthy person, but also brings tangible benefits to him. In particular, this substance and its salts:

• have a positive effect on the condition and functioning of the digestive system;
• stimulate muscle function;
• normalize the functioning of the nervous system;
• have a beneficial effect on the functioning of the female genitourinary system (help prevent the development of amenorrhea and female infertility, get rid of pain and heavy bleeding during menstruation, eliminate the unpleasant symptoms of menopause);
• prevent the development of infertility and impotence in men;
• have excellent bactericidal properties;
• are recognized as indispensable assistants in the fight against intestinal infections, tuberculosis, rhinitis, chlamydia, sinusitis, migraines, rheumatism and other pathologies.

New Year's video recipe:

The harmful properties of this compound appear when it enters the body in excess along with food that has undergone culinary processing, or during metabolic failures. Excess substances react chemically with magnesium, calcium and iron cations, forming crystals that irritate the tissues of the urinary tract and kidneys (that is, provoking the development of urolithiasis or kidney stones). Along with this, excessive consumption of foods high in oxalic acid can cause the following pathologies:

• disturbances in the functioning of the heart;
• deterioration of vascular condition;
• the appearance of aching or sharp pain in the abdomen, groin;
• stomach disorders accompanied by stool disorders;
• malfunctions of the respiratory system.

Safe consumption standards for oxalic acid

It has been proven that healthy people can eat foods rich in oxalic acid and oxalates without worrying about the onset of adverse consequences for the body. In this case, you only need to ensure that in every 100 g of consumed products there is no more than 50 mg of this substance and its salts. At the same time, individuals suffering from gout, kidney disease, rheumatoid arthritis or metabolic disorders are advised to strictly follow a diet that minimizes the consumption of this compound.

What foods contain oxalic acid?

The main sources of oxalic acid are plant products. Moreover, in the leaves of plants the concentration of this compound is significantly higher than in their stems or roots. This substance is found rarely and in small quantities in dairy products, fish and meat.

Food products containing oxalic acid are conventionally divided into the following groups:

• containing this substance in high concentrations - cocoa beans, chard, rhubarb, beets, spinach, wheat germ, some nuts, dry cookies;
• with a moderate content of the specified compound - chocolate, leeks, oatmeal, parsley, raspberries, grapes, celery, red currants, green peas, strawberries, eggplants, parsnips, plums, fruit jams and marmalade;
• low in oxalic acid and oxalates - fruit juices, pork, animal liver, bacon, sea fish, dairy products, pasta, tomato juice, mushrooms, cucumbers, tomatoes, dried fruits, tea, black currants, coffee, onions and green onions, garden fruits, pineapples, cauliflower, etc.

More detailed information on the content of this compound and its salts in food products is collected in the table.

List of food products	Content of oxalic acid, mg in every 100 g of edible part of the original product
Stewed rhubarb	866,4
Boiled spinach	754,1
658,7
Cocoa powder	633,5
Canned rhubarb	604,3
Spinach raw	602,9
Beet	503,4
Sprouted wheat grains	271,2
Pecans	208,7
Crackers	206,8
Roasted peanuts	188,1
Black chocolate	118,4
Parsley	101,8
Lime, lemon peel	94,8
Leek	88,9
Oatmeal	40,9
Grape	26,1
Celery	21,2
Red Ribes	19,2
Eggplant	18,4
Strawberry	16,1
Green peas	15,6
Raspberries	14,9
Fruit and berry jams, preserves	about 11.3
Seed parsnip	10,9
Marmalade	10,7
Plums	10,7
Liver (pork, beef, chicken)	about 7.4
Cranberry juice	6,9
Prunes	5,9
Grape juice	5,9
Black Eyed Peas	5,4
Tomato juice	5,4
Peaches	5,1
Sardines	4,9
Black currant	4,8
White bread	4,6
Black tea	4,3
Oranges	4,2
Carrot	4,1
Bacon	3,4
Coffee	3,3
Apples	3,2
Onion	3,1
Apricots	2,9
Pears	2,9
Mushrooms of all kinds	about 2.2
Tomatoes	1,9
Pork	1,8
Spaghetti	1,6
Cherry	1,2
Egg noodles	1,2
Cauliflower	1,2
Pineapples	1,1
Carbonated sweet drinks	1,1
cucumbers	1,1
Green onion	0,9
Orange juice	0,6
Sea fish	0,4
Radish	0,4
Milk	0,2

How to avoid excess accumulation of oxalates in the body?

In order to avoid the consequences of excessive accumulation of oxalic acid in the body and its deposits in organs and tissues in the form of salts, it is necessary:

• try to eat vegetables raw;
• Before cooking foods, immerse them in boiling water for several minutes;
• When cooking vegetables, change the water several times;
• combine the use of foods containing this substance and calcium;
• use only young, fresh vegetable leaves for cooking;
• drink more than one and a half liters of pure or mineral water during the day (consumption of soups and other drinks does not count towards this norm), as well as at least 100 g of lemon juice (it is advisable to add it in small quantities to water and other drinks);
• Avoid overdosing on vitamin C, try to get ascorbic acid from foods, and not from vitamin-mineral complexes.

It is important to remember that the first signs of accumulation in the body of excess oxalic acid, its salts and symptoms of the development of associated pathologies are:

• periodic pain in the kidney area, lower abdomen, lower back;
• the appearance of blood or pus in the urine;
• discharge of small stones along with urine (as a rule, discharge occurs after renal colic with kidney stones).

If such symptoms are detected, it is necessary to seek professional medical help as soon as possible.

- are colorless monoclinic hygroscopic crystals, easily soluble in water, limited - in ethyl alcohol and diethyl ether, insoluble in chloroform, petroleum ether and benzene.
Oxalic acid is a dibasic saturated carboxylic acid. Belongs to strong organic acids. It has all the chemical properties characteristic of carboxylic acids. Salts and esters of oxalic acid are called oxalates. Oxalic acid forms acidic and medium esters, amides, and acid chloride.
In nature it is found in sorrel, rhubarb and some other plants in free form and in the form of potassium and calcium oxalates.
Density 1.36 g/cm³. Melting point - 189.5° C, sublimation temperature - 125° C, decomposition temperature - 100-130° C, decarboxylation temperature - 166-180° C.

Chemical formula: C 2 H 2 O 4

Use of oxalic acid.
- in the chemical industry (organic synthesis, in the production of plastics, inks, in the synthesis of dyes, as a component of pyrotechnic compositions);
- in chemical metallurgy (as a component of compositions for cleaning metals from rust, scale, oxides); - in analytical chemistry (as a precipitant for rare earth elements);
- in microscopy (as a section bleach);
- in the textile and leather industry (mordant in calico printing and when dyeing wool and silk, when tanning leather);
- in the production of synthetic detergents (as a bleaching and disinfectant, a means for cleaning and removing urinary stones, hardness salts and rust);
- in cosmetics (as an active additive in whitening creams and freckle creams);
- in water purification systems (chemical method of purification and reduction of water hardness, purification of coolants at nuclear power plants);
- in medicine and pharmaceuticals.

Physico-chemical characteristics of oxalic acid:

Safety requirements.
Oxalic acid is a flammable substance; in the settled state, oxalic acid dust is fire hazardous; in terms of the degree of impact on the body, it belongs to substances of the 2nd hazard class.
It has a strong irritant effect on the skin, mucous membranes of the eyes and upper respiratory tract. Oxalic acid and its salts are toxic. When working with oxalic acid, PPE should be used.

Oxalic acid (ethanedioic acid) HOOCCOON is a dibasic saturated carboxylic acid. Belongs to strong organic acids. It has all the chemical properties characteristic of carboxylic acids. Salts and esters of oxalic acid are called oxalates. In nature, it is found in sorrel, rhubarb, carambola and some other plants in free form and in the form of potassium and calcium oxalates. Oxalic acid was first synthesized in 1824 by the German chemist Friedrich Wöhler from cyanogen. Oxalic acid (or oxalate ion C 2 O 4 2−) is a reducing agent (discolors the KMnO 4 solution).

Receipt

In industry, oxalic acid is obtained by the oxidation of carbohydrates, alcohols and glycols with a mixture of HNO 3 and H 2 SO 4 in the presence of V 2 O 5, or by the oxidation of ethylene and acetylene HNO 3 in the presence of PdCl 2 or Pd(NO 3) 2, as well as by the oxidation of propylene with liquid NO2. A promising method for obtaining oxalic acid from sodium formate:

$\backslash mathsf(NaOH\; +\; CO\; \backslash \; \backslash xrightarrow()\; \backslash \; HCOONa\; \backslash xrightarrow[-H\_2]()\; \backslash \; NaOOC\backslash text(-)COONa\; \backslash \; \backslash xrightarrow(H^+)\; \backslash \; HOOC\backslash text(-)COOH)$

Properties

• Enthalpy of combustion (Δ H 0 combustion) −251.8 kJ/mol
• Decarboxylation temperature 166-180 °C

Application

In laboratories, oxalic acid is sometimes used to produce hydrogen chloride and hydrogen iodide:

$\backslash mathsf(H\_2C\_2O\_4\; +\; Cl\_2\; \backslash rightarrow\; 2HCl\backslash uparrow\; +\; 2CO\_2\backslash uparrow)$

Oxalic acid is also used for the laboratory synthesis of chlorine dioxide:

$\backslash mathsf(2KClO\_3\; +\; H\_2C\_2O\_4\; \backslash rightarrow\; K\_2CO\_3\; +\; 2ClO\_2\backslash uparrow\; +\; CO\_2\backslash uparrow\; +\; H\_2O)$

Oxalic acid and oxalates are used in the textile and leather industries as a mordant. They serve as components of anode baths for the deposition of metal coatings - aluminum, titanium and tin. Oxalic acid and oxalates are reagents used in analytical and organic chemistry. They are included in compositions for removing rust and oxide films on metal; used for the precipitation of rare earth elements.

Oxalic acid derivatives - dialkyl oxalates, mainly diethyl oxalate And dibutyl oxalate- used as cellulose solvents. A number of oxalic acid esters and substituted phenols are used as chemiluminescent reagents.

Danger

Oxalic acid is moderately toxic. Some salts of oxalic acid - oxalates, in particular calcium oxalate and magnesium oxalate, are very poorly soluble in water and settle in the renal pelvis in the form of stones of various sizes (sand, stones), sometimes of bizarre shape (coral stones).

The maximum permissible concentration in the water of household reservoirs is 0.2 mg/l.

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Literature

• Tuturin N.N.// Encyclopedic Dictionary of Brockhaus and Efron
• Artsikhovsky V.M.// Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
• Zefirov N.S. and etc. vol.5 Tri-Yatr // Chemical encyclopedia. - M.: Great Russian Encyclopedia, 1998. - 783 p. - ISBN 5-85270-310-9.

Excerpt characterizing oxalic acid

- Ah, vous expediez le courier, princesse, moi j"ai deja expedie le mien. J"ai ecris a ma pauvre mere, [Ah, you are sending a letter, I have already sent mine. “I wrote to my poor mother,” the smiling m lle Bourienne spoke quickly in a pleasant, rich voice, burring in r and bringing with her into the concentrated, sad and gloomy atmosphere of Princess Marya a completely different, frivolously cheerful and self-satisfied world.
“Princesse, il faut que je vous previenne,” she added, lowering her voice, “le prince a eu une altercation,” “alternation,” she said, especially graceful and listening to herself with pleasure, “une altercation avec Michel Ivanoff.” Il est de tres mauvaise humeur, tres morose. Soyez prevenue, vous savez... [We must warn you, princess, that the prince has sorted things out with Mikhail Ivanovich. He is very out of sorts, so gloomy. I'm warning you, you know...]
“Ah l chere amie,” answered Princess Marya, “je vous ai prie de ne jamais me prevenir de l"humeur dans laquelle se trouve mon pere. Je ne me permets pas de le juger, et je ne voudrais pas que les autres le fassent [Ah, my dear friend! I asked you never to tell me what state of mind the priest is in. I will not allow myself to judge him and would not want others to judge him either.]
The princess looked at her watch and, noticing that she had already missed the time she should have used to play the clavichord by five minutes, she went to the sofa with a frightened look. Between 12 and 2 o'clock, in accordance with the routine of the day, the prince rested, and the princess played the clavichord.

The gray-haired valet sat dozing and listening to the prince's snoring in the huge office. From the far side of the house, from behind the closed doors, difficult passages of Dussek's sonata were heard twenty times repeated.
At this time, a carriage and britzka drove up to the porch, and Prince Andrei got out of the carriage, dropped off his little wife and let her go ahead. Gray-haired Tikhon, in a wig, leaned out of the waiter's door, reported in a whisper that the prince was sleeping, and hastily closed the door. Tikhon knew that neither the arrival of his son nor any unusual events should have disrupted the order of the day. Prince Andrei apparently knew this as well as Tikhon; he looked at his watch, as if to see if his father’s habits had changed during the time during which he had not seen him, and, making sure that they had not changed, he turned to his wife:
“He’ll get up in twenty minutes.” “Let’s go to Princess Marya,” he said.
The little princess gained weight during this time, but her eyes and short lip with a mustache and smile rose just as cheerfully and sweetly when she spoke.
“Mais c"est un palais,” she said to her husband, looking around, with the expression with which one speaks of praise to the owner of the ball. “Allons, vite, vite!... [Yes, this is a palace! – Let’s go quickly, quickly!...] - She , looking around, smiled at Tikhon, her husband, and the waiter who saw them off.
- C "est Marieie qui s" exercise? Allons doucement, il faut la surprendre. [Is this Marie exercising? Hush, let's take her by surprise.]
Prince Andrei followed her with a courteous and sad expression.
“You have grown old, Tikhon,” he said, passing, to the old man who was kissing his hand.
In front of the room in which the clavichord could be heard, a pretty blond Frenchwoman jumped out of a side door.
M lle Bourienne seemed distraught with delight.
- Ah! “quel bonheur pour la princesse,” she spoke. - Enfin! Il faut que je la previenne. [Oh, what joy for the princess! Finally! We need to warn her.]
“Non, non, de grace... Vous etes m lle Bourienne, je vous connais deja par l"amitie que vous porte ma belle soeur,” said the princess, kissing the Frenchwoman. “Elle ne nous attend pas?” [No, no, please ... You are Mamzel Bourien; I already know you from the friendship that my daughter-in-law has for you. Isn’t she expecting us?]
They approached the door of the sofa, from which they could hear the passage being repeated again and again. Prince Andrey stopped and winced, as if expecting something unpleasant.
The princess entered. The passage broke off in the middle; a cry was heard, the heavy feet of Princess Marya and the sounds of kisses. When Prince Andrei entered, the princess and princess, who had only met briefly once during Prince Andrei’s wedding, clasped their hands and pressed their lips firmly to the places they had been in in the first minute. M lle Bourienne stood near them, pressing her hands to her heart and smiling piously, apparently as ready to cry as to laugh.
Prince Andrey shrugged his shoulders and winced, as music lovers wince when they hear a false note. Both women released each other; then again, as if afraid of being late, they grabbed each other by the hands, began to kiss and tear off their hands, and then again began to kiss each other on the face, and completely unexpectedly for Prince Andrei, both began to cry and began to kiss again. M lle Bourienne also began to cry. Prince Andrei was obviously embarrassed; but it seemed so natural to the two women that they were crying; it seemed that they did not even imagine that this meeting could take place otherwise.
- Ah! here!…Ah! Marieie!... – both women suddenly spoke and laughed. – J"ai reve cette nuit... – Vous ne nous attendez donc pas?... Ah! Marieie,vous avez maigri... – Et vous avez repris... [Ah, dear!... Ah, Marie!... – And I saw it in a dream. – So you weren’t expecting us?... Oh, Marie, you’ve lost so much weight. - And you’ve gained so much weight...]
“J"ai tout de suite reconnu madame la princesse, [I immediately recognized the princess,] - inserted m lle Burien.
“Et moi qui ne me doutais pas!...” exclaimed Princess Marya. - Ah! Andre, je ne vous voyais pas. [But I didn’t suspect!... Oh, Andre, I didn’t even see you.]
Prince Andrei kissed his sister hand in hand and told her that she was the same pleurienicheuse [crybaby] as she always was. Princess Marya turned to her brother, and through her tears, the loving, warm and gentle gaze of her large, beautiful, radiant eyes at that moment rested on the face of Prince Andrei.
The princess spoke incessantly. Every now and then a short upper lip with a mustache would fly down for a moment, touch, where necessary, the ruddy lower lip, and again a smile would be revealed, shining with teeth and eyes. The princess told an incident that happened to them on Spasskaya Hill, which threatened her with danger in her position, and immediately after that she said that she had left all her dresses in St. Petersburg and would wear God knows what here, and that Andrei had completely changed, and that Kitty Odyntsova married an old man, and that there is a groom for Princess Marya pour tout de bon, [quite serious,] but we’ll talk about that later. Princess Marya still silently looked at her brother, and in her beautiful eyes there was both love and sadness. It was clear that she had now established her own train of thought, independent of her daughter-in-law’s speeches. In the middle of her story about the last holiday in St. Petersburg, she turned to her brother:
– And you are determined to go to war, Andre? – oia said, sighing.
Lise shuddered too.
“Even tomorrow,” answered the brother.
– II m"abandonne ici,et Du sait pourquoi, quand il aur pu avoir de l"avancement... [He leaves me here, and God knows why, when he could get a promotion...]
Princess Marya did not listen to the end and, continuing the thread of her thoughts, turned to her daughter-in-law, pointing at her belly with gentle eyes:
- Maybe? - she said.
The princess's face changed. She sighed.
“Yes, I guess,” she said. - Ah! It's very scary…
Lisa's lip dropped. She brought her face closer to her sister-in-law's and suddenly began to cry again.
“She needs to rest,” said Prince Andrei, wincing. – Isn’t it true, Lisa? Take her to your place, and I’ll go to the priest. What is he, still the same?

Hi all!

What do you think of my story about doctors in the previous article? What do you think about this?

In general, for some reason, life often confronts me with such misunderstandings.

I remember when I moved from Kurchatov to Ust-Kamenogorsk, I went to the Public Service Center (PSC) to register, where the operator started filling out a form for me and got to education. When asked what my degree was, I answered “analytical chemist.”

The poor girl operator (she looked about 18 years old, no more) had square eyes and she asked almost in a whisper: “And this means a chemistry teacher, right?” After all the ordeals with the apartment and registration, I didn’t care anymore, so I nodded: “Yes, write, chemistry teacher.”

It’s bad to have a little-known profession

And after this short digression, I return to the most interesting chemical substances that I recently started talking about - acids.

I have already talked about lemon and acetylsalicylic acid.

Today we will talk about what oxalic acid is: use in everyday life, properties, precautions when working with it. Or do you think you don't need it because you don't encounter it anywhere?

In vain. Let's get a look.

It is an organic acid that occurs naturally in some plants. Most of it is found in sorrel, spinach and rhubarb. This is what gives them their sour taste. Oddly enough, there is a lot of it in chocolate, beets and strong black tea.

Salts of oxalic acid are called oxalates.

I think you have heard this word often, especially those who have problems with salt deposition in joints or kidney stones - these are insoluble calcium oxalates. That is why during treatment, doctors recommend reducing the consumption of foods that contain a lot of oxalic acid.

Natural compounds of oxalic acid are most often potassium oxalates.

Interestingly, oxalic acid played a significant role in the development of organic chemistry as a science.

The fact is that at the beginning of the 19th century, scientists clearly divided all substances into so-called mineral and organic.

Moreover, the former could only exist in living organisms, and the latter, respectively, in inanimate objects.

And in 1824, the German chemist Friedrich Wöhler destroyed these ideas by obtaining an organic substance (oxalic acid) from inorganic substances.

Well, after that similar discoveries came one after another. As a result, scientists came to the conclusion that there is no gap between inorganic and organic substances; the same laws apply to all of them.

Here is an interesting substance - this oxalic acid or “sorrel”, as chemists in laboratories call it, often using it to prepare mixtures for washing chemical dishes.

Application

Needless to say, it is huge:

• for the production of food additives,
• in cosmetology - as a whitening component in creams.
• to reduce water hardness and to clean it from impurities,
• as an insecticide, it is especially in demand among beekeepers,
• for tanning leather, as well as for dyeing natural silk and wool fabrics,
• the industrial synthesis of dyes and plastics is also not complete without its participation.

Well, in everyday life its main use is as a component of detergents as a bleaching and disinfectant substance.

The most common application is rust removal.

Moreover, this property of oxalic acid to easily deal with rust is valid for plumbing fixtures, metal parts, and even rust stains on clothes.

Once upon a time, one of my colleagues hung his white sweater to dry on the radiator and did not notice that there were streaks of rust on it. As a result, there were rust stains on the sweater.

I was working in a laboratory at the time, and we gave him some oxalic acid, with which he saved his clothes.

Nowadays, it is difficult to find and buy pure oxalic acid, at least here in Kazakhstan, but it can easily be found in a variety of powders for cleaning pipes, detergents, and also Antiscale.

By the way, while I was writing, they told me that it can be found in stores for beekeepers and in veterinary stores.

Well, how to use it? Easily. Dissolve a teaspoon with a liter of warm water - and the anti-rust solution is ready.

Just don't forget about precautions! This substance belongs to the second class of danger - it irritates the upper respiratory tract and has a pronounced irritant effect on the skin and mucous membranes.

Moreover, this applies not only to the acid itself, but also to its salts. In addition, its dust is a fire hazard.

Organic and inorganic oxalic acid

And now - what caused my great bewilderment, and then indignation. When I was looking for material for this article, I rummaged through a lot of reference and specialized literature, both in paper and electronic form, and also tried to search for information on the Internet. I say “tried” because in almost every second article I came across such horror... I don’t even know what words to describe it.

Judge for yourself, here is a screenshot of part of the article on one of these sites:

How about this:

How can organic oxalic acid suddenly turn into inorganic acid?! What nonsense! A substance is always one; if some chemical transformations occur with it, then it turns into another substance, which will have a different name, have a different structure and other properties.

But such a thing does not happen that a substance suddenly undergoes some kind of chemical transformation and remains itself!

And organic calcium is synonymous with white soot! There is no such thing as organic calcium.

I was especially pleased with the “destruction of calcium” that occurs during food processing. Is it, by any chance, processed in a nuclear reactor?

After all, only nuclear reactions can destroy any chemical element.

In short, if you see a site like this, run away from it as fast as you can. Their authors are illiterate and stupid. They are illiterate because they do not know a basic school chemistry course, and they are stupid because they copy such nonsense from each other without even thinking about what they are writing.

And no Vikium will help them.

It’s like in the article about water with a “living active medium”, which I already wrote about.

Accordingly, the big question is whether you can trust advice from such sites. If you want, try it, risk your health. But I won't.

By the way, here is an interesting video that amazed me no less than these sites:

Good luck to everyone and have a good working week!

Natalya Bryantseva

Oxalic acid (ethanedioic acid)

Oxalic acid

- are colorless monoclinic hygroscopic crystals, easily soluble in water, limited - in ethyl alcohol and diethyl ether, insoluble in chloroform, petroleum ether and benzene.
Oxalic acid is a dibasic saturated carboxylic acid.

Belongs to strong organic acids. It has all the chemical properties characteristic of carboxylic acids. Salts and esters of oxalic acid are called oxalates.

Oxalic acid forms acidic and medium esters, amides, and acid chloride.
In nature it is found in sorrel, rhubarb and some other plants in free form and in the form of potassium and calcium oxalates.
Density 1.36 g/cm³.

Melting point - 189.5° C, sublimation temperature - 125° C, decomposition temperature - 100-130° C, decarboxylation temperature - 166-180° C.

Chemical formula: C2H2O4

Use of oxalic acid.
— in the chemical industry (organic synthesis, in the production of plastics, inks, in the synthesis of dyes, as a component of pyrotechnic compositions);
- in chemical metallurgy (as a component of compositions for cleaning metals from rust, scale, oxides); - in analytical chemistry (as a precipitant for rare earth elements);
— in microscopy (as a section bleach);
- in the textile and leather industry (mordant in calico printing and in dyeing wool and silk, in leather tanning);
— in the production of synthetic detergents (as a bleaching and disinfectant, a means for cleaning and removing urinary stones, hardness salts and rust);
— in cosmetics (as an active additive in whitening creams and freckle creams);
— in water purification systems (chemical method of purification and reduction of water hardness, purification of coolants at nuclear power plants);
- in medicine and pharmaceuticals.

Physico-chemical characteristics of oxalic acid:

Safety requirements.
Oxalic acid is a flammable substance; in the settled state, oxalic acid dust is fire hazardous; in terms of the degree of impact on the body, it belongs to substances of the 2nd hazard class.
It has a strong irritant effect on the skin, mucous membranes of the eyes and upper respiratory tract.