Magnesium hydroxide is an inorganic substance, it is a poorly soluble compound, which is why a precipitate appears when it is formed in aqueous solutions. The formula of magnesium hydroxide is Mg (OH) 2, that is, it is a two-acid base. More soluble in water than typical insoluble bases, but less soluble than calcium hydroxide. For this reason, it is classified as a poorly soluble compound.

Distribution in nature

Magnesium hydroxide occurs naturally as the mineral brucite. Large deposits of this rock are a rarity. In Russia, it is mined at the Kuldurskoye field, where its reserves are estimated at 14 million tons. Production on it is going at a rate of about 250 thousand tons of product per year, but since this year, production volumes have doubled. The reason for this was the good demand for this mineral abroad. Japan is the largest importer.

Brucite looks like white, gray or greenish-white crystals with a glassy sheen at the break. It has a fairly low hardness, so it can be easily cut with a knife. May contain impurities. Depending on their quantity and type, several subspecies of this mineral are distinguished. So, ferronemalite contains, in addition to magnesium hydroxide, 5% iron in the form of oxide, and ferrobrusite - already as much as 36%. Iron oxide has a brown color (the color of rust), so these minerals take on the same shade instead of the usual light green. There is also mangobrusite. Manganese acts as an impurity here. Such a mineral already has a honey-yellow color. But upon contact with atmospheric oxygen, the mineral quickly loses its beautiful color and quickly turns black.

This mineral is used mainly as a raw material. Oxide and other magnesium compounds, fluxes, and various refractory materials are obtained from it. But brucite can be used without any treatment. So, this mineral is used to purify gases from chlorine and for sorption filtration of water.

Receipt

The main reaction for obtaining insoluble hydroxides is the reaction of the interaction of alkalis with magnesium salts. For example, when magnesium sulfate reacts with sodium hydroxide. This is a good illustration. Another example is the interaction of magnesium chloride and potassium hydroxide.

In ionic form, all such reactions are written as:

Mg2+ + OH- → Mg(OH)2

When magnesium or its oxide reacts with water, a hydroxide can also be obtained. This reaction proceeds very slowly and only when heated.

There is such a fairly common mineral - dolomite. From a chemical point of view, it is a mixture of calcium carbonate and magnesium. When this mineral is treated with an aqueous solution of magnesium chloride, an insoluble hydroxide precipitates when heated:

MgCO3 CaCO3 + 2H2O + MgCl2 → Mg(OH)2 + CaCl2 + 2CO2

Physical properties

In dry form, magnesium hydroxide is a white crystalline substance. It has no smell, but it has an inherent taste of alkali. It is slightly soluble in water (only 0.6 mg per 100 ml of water). But even despite this, its aqueous solutions have a slightly alkaline environment and paint the indicators in the appropriate colors. But this compound dissolves in solutions of ammonium salts. It does not melt, because at a temperature of 480 oC it decomposes into magnesium oxide and water, like any other insoluble base. Density under normal conditions: 2.4 g/cm3.

Chemical properties

Magnesium hydroxide is a typical insoluble base. This determines its chemical properties. So, for example, magnesium hydroxide reacts with acids, acid oxides and non-metals:

Due to the latter reaction, it tends to absorb carbon dioxide directly from the air with the formation of carbonate, therefore it is not recommended to store this substance open for a long time.

It also interacts with salts if the reaction results in a precipitate or gas:

As mentioned above, when heated, magnesium hydroxide decomposes according to the equation:

Mg(OH)2 → H2O + MgO

As for the formation of complex compounds, where the magnesium cation would act as a ligand, there are contradictory data on this subject. Some sources indicate that magnesium is not prone to their formation, and there are only unstable compounds with magnesium halides. Other sources indicate that magnesium hydroxide can react with hot alkalis to form hydromagnesates:

Mg(OH)2 + 2NaOH → Na2

Application in medicine

In medicine, suspensions based on magnesium hydroxide are used as an antacid. This is facilitated by the main properties. Once in the stomach, magnesium hydroxide reduces its acidity by neutralizing hydrochloric acid. It is used for gastritis, peptic ulcer of the stomach and duodenum. Preparations based on it do not reduce the acid-base balance and do not violate the secretion of hydrochloric acid. But even despite this, the drug has a number of limitations and is contraindicated in people with hypersensitivity to magnesium hydroxide.

The product of the interaction of magnesium hydroxide and hydrochloric acid of gastric juice is magnesium chloride. It is a strong laxative (action occurs in 2-6 hours). Therefore, magnesium hydroxide is the active ingredient in some preparations in this area. Excess magnesium in the body is easily excreted by the kidneys, but if a person suffers from any diseases of these organs, then he can get an excess of magnesium in the body when taking drugs (hypermagnesemia).

Another property of this compound is muscle relaxation. Sometimes preparations containing magnesium hydroxide are prescribed to women with a threatened miscarriage.

Application in other industries

Magnesium hydroxide is also used in the food industry as an additive E528. In products, it regulates acidity and stabilizes color. Magnesium hydroxide is also used to bind sulfur dioxide, the appearance of which is undesirable in food products. It is used in the production of canned vegetables, sauces, marinade and cheese. This additive is considered harmless but is banned in Australia, the UK and New Zealand.

Magnesium hydroxide is also used as a flame retardant additive in polymers (PVC, polyolefins), as an additive in detergents and toothpastes, for sugar refining and wastewater treatment.

The oxide obtained from magnesium hydroxide is a rather useful compound. It is able to withstand temperatures of about 3000 degrees, so it is used as a refractory. So, it is added to bricks, from which blast furnaces are then made. Magnesium oxide is also used as a sorbent for the purification of petroleum products. The abrasive ability of this compound is also high. It is used to clean and polish the surfaces of parts in the electronics industry.

Magnesium hydroxide, magnesium hydroxide- an inorganic compound of the composition Mg (OH) 2. White crystals that are poorly soluble in water. The compound exhibits weak basic properties.

It is used as a drug to reduce the acidity of gastric juice and as an antidote for arsenic poisoning. Intermediate in the synthesis of metallic magnesium.

Distribution in nature

Minerals, which include magnesium hydroxide, are quite rare. Among these minerals, brucite is the most important. In addition to the main compound, Mg (OH) 2, it may contain impurities MnO, FeO, Fe 2 O 3. Brucite is formed as a result of the hydrolysis of natural magnesium compounds soluble in meadows.

Mg (OH) 2 is also found in the mineral hydromagnesite, which is close in composition to a mixture of magnesium hydroxide and carbonate, - 4MgCO 3 Mg (OH) 2 2H 2 O.

Physical properties

Magnesium hydroxide are white crystals that are poorly soluble in water and do not conduct electricity. Actively dehumidifies the air by absorbing water and carbon dioxide. It dissolves well in ammonium salts.

Receipt

Given the low prevalence of magnesium hydroxide in mineral deposits, it is mined in a different way. For the needs of industry, Mg (OH) 2 is obtained by precipitation of sea water and brines. For the first time, the extraction of hydroxide from sea water was used in 1865 on the coast of the French Mediterranean.

In laboratory languages, magnesium hydroxide can be synthesized by burning metallic magnesium in water vapor:

The precipitation of sparingly soluble hydroxide is also used in the interaction of magnesium salts with alkalis and ammonium hydroxide.

However, precipitation with ammonium hydroxide occurs entirely due to the constant reduction of OH - ions.

Chemical properties

Magnesium hydroxide decomposes when heated above 350°C in vacuum and at 800°C in air:

The compound is a weak base, interacts with acids, ammonium salts and acid oxides (actively absorbs carbon dioxide from the air):

When heated, it reacts with some non-metals, which as a result form the corresponding hydrides:

Complexation with inorganic ligands for Mg 2+ cations is uncharacteristic (unstable complexes with oxygenated molecules are known for magnesium halides), therefore Mg (OH) 2 is insoluble in meadows.

Application

Magnesium hydroxide is used as an intermediate in the synthesis of magnesium metal. It is used to purify sugar, water in boiler houses, in the manufacture of toothpastes.

In medicine

Magnesium hydroxide is widely used as an antacid for increased acidity of gastric juice (for gastritis, gastric ulcer and duodenal ulcer). Included in the drug "Maalox" (acronym for "ma manure al Yuminov ox id"), as well as its analogue "almagel", which reduce acidity.

By neutralizing the perchloric acid contained in the stomach, it turns into magnesium chloride, which has a laxative effect. It is used for poisoning with acids and arsenic compounds.

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Used as a fertilizer.

Magnesium carbonate MgCO 3 . Colorless trigonal diamagnetic crystals. Slightly soluble in cold water. In hot water it turns into basic carbonates. Soluble in acids. Decomposes on heating. Obtained by treating magnesium chloride or sulfate with sodium or calcium carbonate in excess of carbon dioxide. In industry, it can be obtained from natural minerals magnesite and dolomite.

It is used for the manufacture of refractory bricks, in the production of Sorel cement, as a filler for linoleum, rubber, paper.

Magnesium bicarbonate Mg(HCO 3 ) 2 . Obtained in solution by passing carbon dioxide through an aqueous suspension of magnesium oxide, hydroxide or carbonate. The presence of magnesium bicarbonate in water causes its temporary hardness, which is eliminated by boiling or adding soda.

Chemical properties of magnesium oxide and hydroxide

Magnesium oxide (burnt magnesia, periclase) is a chemical compound with the formula MgO, colorless crystals, insoluble in water, fire and explosion-proof. The main form is the mineral periclase.

Chemical properties

1) Easily reacts with dilute acids and water to form salts and Mg(OH) 2:

MgO + 2HCl> MgCl 2 + H 2 O;

MgO + H 2 O > Mg (OH) 2.

Magnesium hydroxide is an inorganic hydroxide of the alkaline earth metal magnesium. Belongs to the class of insoluble bases.

Chemical properties:

1) Decomposition when heated up to 350°C:

2) Interaction with acids to form salt and water (neutralization reaction):

3) Interaction with acid oxides to form salt and water:

4) Interaction with hot concentrated solutions of alkalis with the formation of hydroxomagnesates:

Ways to get an element.

The usual industrial method for producing metallic magnesium is the electrolysis of a mixture of anhydrous magnesium chlorides MgCl 2 , sodium NaCl and potassium KCl. In this melt, magnesium chloride undergoes electrochemical reduction:

MgCl 2 (electrolysis) \u003d Mg + Cl 2.

The molten metal is periodically taken from the electrolysis bath, and new portions of magnesium-containing raw materials are added to it. Since the magnesium obtained in this way contains a relatively large amount - about 0.1% of impurities, if necessary, "raw" magnesium is subjected to additional purification. For this purpose, electrolytic refining, vacuum remelting with the use of special additives - fluxes, which “take away” impurities from magnesium, or distillation (sublimation) of the metal in vacuum are used. The purity of refined magnesium reaches 99.999% and higher.

Another method for obtaining magnesium has also been developed - thermal. In this case, silicon or coke is used to reduce magnesium oxide at high temperature:

magnesium chemical compound

MgO + C = Mg + CO

The use of silicon makes it possible to obtain magnesium from raw materials such as CaCO 3 ·MgCO 3 dolomite without preliminary separation of magnesium and calcium. With the participation of dolomite, reactions occur:

CaCO 3 MgCO 3 \u003d CaO + MgO + 2CO 2,

2MgO + 2CaO + Si = Ca 2 SiO 4 + 2Mg.

The advantage of the thermal process is that it makes it possible to obtain higher purity magnesium. To obtain magnesium, not only mineral raw materials are used, but also sea water.

Structural formula

Russian name

Latin name for magnesium hydroxide

Magnesii hydroxydum ( genus. Magnesii hydroxydi)

Gross formula

Mg-H 2 O 2

Pharmacological group of the substance Magnesium hydroxide

Nosological classification (ICD-10)

CAS code

1309-42-8

Characteristics of the substance Magnesium hydroxide

Formed when magnesium oxide comes into contact with water. Magnesium oxide is a light, fine, white powder. Practically insoluble in water, soluble in dilute hydrochloric acid.

Pharmacology

pharmachologic effect- laxative, antacid.

Neutralizes free hydrochloric acid of gastric juice with the formation of magnesium chloride. Passing into the intestine, magnesium chloride has a laxative effect, acting as a saline laxative (poorly absorbed, increases the osmotic pressure in the intestinal lumen, promotes fluid flow along the concentration gradient, increases the volume of intestinal contents, stretching its walls and stimulating peristalsis). Magnesium ions are excreted with the contents of the intestine in the form of sparingly soluble hydroxide and water-soluble salts - chloride and bicarbonate. It inactivates pepsin and binds bile acids that enter the stomach as a result of reflux from the duodenum, has a protective effect on the mucous membrane of the stomach and duodenum, incl. with gastric ulcer. It is not consumed immediately in the stomach and can neutralize hydrochloric acid secreted some time after taking the drug, thus it is characterized by a rapid and long-lasting antacid effect, which is not accompanied by secondary hypersecretion of hydrochloric acid and changes in acid-base balance. Helps to increase peristalsis of all parts of the intestine. The laxative effect occurs after 0.5-6 hours. When used in patients with impaired renal function, a small amount of magnesium can be absorbed into the blood and the development of toxic reactions, manifested by CNS depression.

Application of the substance Magnesium hydroxide

Chronic gastritis with normal and increased secretion (in the acute phase), peptic ulcer of the stomach and duodenum, discomfort or pain in the epigastrium, heartburn after dietary errors, drinking coffee, alcohol, smoking, constipation.

Contraindications

Hypersensitivity, children's age (up to 3 years, for tablets - up to 6 years).

Side effects of magnesium hydroxide

CNS depression (if for some reason magnesium absorption has taken place), allergic reactions.

Included in medications

ATH:

N.02.B.A.51 Acetylsalicylic acid in combination with other drugs, excluding psycholeptics

Pharmacodynamics:

The mechanism of action of acetylsalicylic acid is based on the inhibition of cyclooxygenase-1, as a result of which the synthesis of thromboxane A2 is blocked and platelet aggregation is suppressed. It is believed that it has other mechanisms for suppressing platelet aggregation, which expands the scope of its application in various vascular diseases. also has anti-inflammatory, analgesic, antipyretic effect.

Magnesium hydroxide, which is part of the combined preparation, protects the mucous membrane of the gastrointestinal tract from the effects of acetylsalicylic acid: neutralizes hydrochloric acid of the stomach (antacid effect), reducing its damaging effect on the mucous membrane.

Pharmacokinetics:

Acetylsalicylic acid is absorbed from the gastrointestinal tract almost completely. Pacetylsalicylic acid is about 15 minutes, because. with the participation of enzymes, it is rapidly hydrolyzed into salicylic acid in the intestine, liver and blood plasma. Communication with plasma proteins is high. P half-life (half-life) salicylic acid is about 3 hours, but it can increase significantly with the simultaneous administration of large doses of acetylsalicylic acid (more than 3 g) as a result of saturation of enzyme systems.

The bioavailability of acetylsalicylic acid is about 70%, but this value fluctuates to a large extent, since it undergoes presystemic hydrolysis (mucosa of the gastrointestinal tract, liver) into salicylic acid under the action of enzymes.

The doses of magnesium hydroxide used do not affect the bioavailability of acetylsalicylic acid. Magnesium is slowly and in small amounts absorbed in the small intestine, bound by plasma proteins by 25-30%. Able to pass through the placental barrier. Magnesium is excreted primarily in the urine, but some is reabsorbed and eliminated from the body in the feces.

Indications:

Primary prevention of cardiovascular diseases such as thrombosis and acute heart failure in the presence of risk factors (eg, diabetes mellitus, hyperlipidemia, arterial hypertension, obesity, smoking, old age).

Prevention of recurrent myocardial infarction and thrombosis of blood vessels.

Prevention of thromboembolism after surgical interventions on the vessels (coronary bypass grafting, percutaneous transluminal coronary angioplasty).

Unstable angina.

IX.I20-I25.I20.0 Unstable angina

IX.I20-I25.I25.2 Past myocardial infarction

IX.I60-I69.I67.9 Cerebrovascular disease, unspecified

IX.I80-I89.I82 Embolism and thrombosis of other veins

IX.I70-I79.I74 Embolism and thrombosis of arteries

XXI.Z40-Z54.Z40 Preventive surgery

Contraindications:

Hypersensitivity to acetylsalicylic acid, excipients of the drug and others non-steroidal anti-inflammatory drugs, cerebral hemorrhage, bleeding tendency (vitamin K deficiency, thrombocytopenia, hemorrhagic diathesis), bronchial asthma induced by salicylates and non-steroidal anti-inflammatory drug, erosive and ulcerative lesions of the gastrointestinal tract (in the acute phase), gastrointestinal bleeding, severe renal failure (Cl creatinine< 10 мл в минуту), беременность (I и III триместры), период лактации, дефицит глюкозо-6-фосфатдегидрогеназы, одновременный прием с метотрексатом (>15 mg per week), children under 18 years of age.

Carefully:

With caution, the drug should be prescribed for gout, hyperuricemia, a history of ulcerative lesions of the gastrointestinal tract or bleeding from the gastrointestinal tract, with renal and / or liver failure, bronchial asthma, hay fever, nasal polyposis, allergic conditions, in the II trimester pregnancy.

Pregnancy and lactation:

The use of salicylates in high doses in the first trimester of pregnancy is associated with an increased incidence of fetal defects. In the second trimester of pregnancy, salicylates can only be prescribed based on a strict assessment of risk and benefit. In the third trimester of pregnancy, salicylates at a high dose (> 300 mg per day) cause inhibition of labor, premature closure of the ductus arteriosus in the fetus, increased bleeding in the mother and fetus, and administration immediately before delivery can cause intracranial hemorrhages, especially in premature babies.

The appointment of salicylates in the I and III trimesters of pregnancy is contraindicated.

Available clinical data are not enough to establish the possibility or impossibility of using the drug during breastfeeding. Before prescribing acetylsalicylic acid during breastfeeding, the potential benefit of drug therapy should be assessed against the potential risk to infants.

Acetylsalicylic acid: passes into breast milk. When taken in normal doses, complications in humans have not been registered. With prolonged use in high doses, entering the body of a child can cause side effects.

Magnesium hydroxide: Magnesium-containing antacids are able to pass into milk, but their concentration is not enough to affect the newborn. Complications in humans have not been reported.

Dosage and administration:

Tablets should be swallowed whole with water. If desired, the tablet can be broken in half, chewed or pre-pounded.

For the primary prevention of cardiovascular diseases, 1 tablet containing acetylsalicylic acid at a dose of 150 mg is prescribed on the first day, then 1/2 tablet 1 time per day.

For the prevention of recurrent myocardial infarction and thrombosis of blood vessels, 1 tablet containing acetylsalicylic acid at a dose of 75-150 mg, 1 time per day is prescribed.

For the prevention of thromboembolism after surgical interventions on the vessels (coronary bypass grafting, percutaneous transluminal coronary angioplasty), 1 tablet containing acetylsalicylic acid at a dose of 75-150 mg, 1 time per day is prescribed.

In case of unstable angina pectoris, 1 tablet containing acetylsalicylic acid at a dose of 75-150 mg is prescribed, 1 time per day.

Side effects:

Allergic reactions: urticaria, angioedema.

From the immune system: anaphylactic reactions.

From the gastrointestinal tract: nausea, heartburn, vomiting, pain in the abdomen, ulcers of the mucous membrane of the stomach and duodenum, incl. perforative, gastrointestinal bleeding, increased activity of liver enzymes, stomatitis, esophagitis, erosive lesions of the upper gastrointestinal tract, strictures, colitis, irritable bowel syndrome.

From the respiratory system: bronchospasm.

From the hematopoietic system: increased bleeding, anemia, hypoprothrombinemia, thrombocytopenia, neutropenia, aplastic anemia, eosinophilia, agranulocytosis.

From the side of the central nervous system: dizziness, headache, insomnia, drowsiness, tinnitus, intracerebral hemorrhage (rare).

Overdose:

Symptoms of an overdose of moderate severity: nausea, vomiting, tinnitus, hearing loss, dizziness, confusion.

Treatment: you should wash the stomach, prescribe, carry out symptomatic therapy.

Symptoms of severe overdose: fever, hyperventilation, ketoacidosis, respiratory alkalosis, coma, cardiovascular and respiratory failure, severe hypoglycemia.

Treatment: immediate hospitalization in specialized departments for emergency therapy - gastric lavage, determination of acid-base balance, alkaline and forced alkaline diuresis, hemodialysis, administration of saline solutions, symptomatic therapy. When performing alkaline diuresis, a pH value between 7.5 and 8 should be achieved. Forced alkaline diuresis should be performed when the plasma salicylate concentration is more than 500 mg/l (3.6 mmol/l) in adults and 300 mg/l (2 ,2 mmol/l) in children.

Interaction:

With simultaneous use enhances the effect of the following drugs:

Methotrexate (by reducing renal clearance and displacing it from its association with proteins);

Heparin and indirect anticoagulants (due to impaired platelet function and displacement of indirect anticoagulants from their association with proteins);

Thrombolytic and antiplatelet and anticoagulant drugs (ticlopidine);

Digoxin (due to a decrease in its renal excretion);

Hypoglycemic agents for oral administration (sulfonylurea derivatives) and insulin (due to the hypoglycemic properties of acetylsalicylic acid itself in high doses and the displacement of sulfonylurea derivatives from association with plasma proteins);

Valproic acid (due to its displacement from its association with proteins).

The simultaneous use of acetylsalicylic acid with ibuprofen leads to a decrease in the cardioprotective effects of acetylsalicylic acid.

An additive effect is observed while taking acetylsalicylic acid with ethanol (alcohol).

Acetylsalicylic acid weakens the effect of uricosuric agents (benzbromarone) due to competitive tubular elimination of uric acid.

By enhancing the elimination of salicylates, systemic glucocorticosteroids weaken their effect.

Antacids and with simultaneous use reduce the absorption of the drug.

Special instructions:

The drug should be used after a doctor's prescription.

Acetylsalicylic acid can provoke bronchospasm, as well as cause asthma attacks and other hypersensitivity reactions. Risk factors include a history of bronchial asthma, hay fever, nasal polyposis, chronic respiratory disease, and allergic reactions to other drugs (eg, skin reactions, itching, urticaria).

Acetylsalicylic acid can cause bleeding of varying severity during and after surgery. A few days before the planned surgical intervention, the risk of bleeding should be assessed in comparison with the risk of ischemic complications in patients taking low doses of acetylsalicylic acid. If the risk of bleeding is significant, acetylsalicylic acid should be temporarily discontinued.

The combination of acetylsalicylic acid with anticoagulants, thrombolytics and antiplatelet drugs is accompanied by an increased risk of bleeding.

Acetylsalicylic acid in low doses can provoke the development of gout in predisposed individuals (having reduced excretion of uric acid).

High doses of acetylsalicylic acid have a hypoglycemic effect, which must be borne in mind when prescribing it to patients with diabetes mellitus receiving hypoglycemic agents.

With the combined appointment of glucocorticosteroids and salicylates, it should be remembered that during treatment, the level of salicylates in the blood is reduced, and after the abolition of glucocorticosteroids, an overdose of salicylates is possible.

Exceeding the dose of acetylsalicylic acid is associated with a risk of gastrointestinal bleeding.

Overdose is especially dangerous in elderly patients.

When combining acetylsalicylic acid with alcohol, the risk of damage to the mucous membrane of the gastrointestinal tract and prolongation of bleeding time is increased.

Instructions