Under normal conditions, phosgene is a gas that condenses into a liquid at temp. kip. and density
Phosgene is very poisonous. It has a strong effect on the respiratory system and mucous membranes. First world war used as It has a pungent suffocating odor.
When exposed to water (or better aqueous alkali), it decomposes to form hydrochloric acid and carbon dioxide:
Phosgene is obtained from chlorine and carbon monoxide in the presence of a catalyst specially treated to increase its porosity:
Phosgene serves starting material for the synthesis of various organic compounds.
Carbon disulfide Of the derivatives of carbonic acid containing sulfur, carbon disulfide is widely used. It is a colorless mobile liquid with a temp. kip. having an ethereal odor (technical carbon disulfide, has bad smell, reminiscent of the smell of radish). Carbon disulfide is poisonous and extremely flammable, as its vapors ignite at low temperatures.
Carbon disulfide is used as a starting product for the synthesis of carbon tetrachloride (p. 74), in the production of viscose fiber (p. 345), and also as a solvent for fats, etc.
Carbon disulfide is obtained by passing sulfur vapor over. hot coal:
Currently, the most cost-effective way to produce carbon disulfide is the interaction of methane with sulfur vapor over silica gel:
Urea (urea) is a complete amide of carbonic acid:
It is one of the first organic substances obtained synthetically from inorganic substances(Wohler, 1828).
Urea is a crystalline substance with a temp. pl. 133 °C, easily soluble in water and alcohol. With one equivalent of acids it forms salts, for example:
When urea solutions are heated in the presence of acids or alkalis, it easily hydrolyzes to form carbon dioxide and ammonia:
When nitrous acid reacts with urea, carbon dioxide, nitrogen and water are formed:
When urea is heated with alcohols, urethanes are obtained - esters of carbamic acid
Urethanes are crystalline substances that are soluble in water.
When urea reacts with formaldehyde in a neutral or slightly alkaline environment at a temperature of about 30 °C, monomethylolurea and dimethylolurea are formed:
These derivatives, when heated in an acidic environment, form urea polymers - the basis of common plastics - aminoplasts (p. 331) and adhesives for gluing wood.
Urea (urea) plays an important role in metabolism in animal organisms; is the final product of nitrogen metabolism, in which nitrogenous substances (for example, proteins), having undergone a series of complex transformations in the body, are excreted in the urine in the form of urea (hence its name).
Urea is a concentrated nitrogen fertilizer (contains 46% nitrogen) and is quickly absorbed by plants. In addition, urea is successfully used to feed livestock.
Currently, urea is used for the separation of paraffin hydrocarbons of normal structure from petroleum products. The fact is that urea crystals form “crystalline pores”, so narrow that hydrocarbons of normal structure penetrate into them, but hydrocarbons with a branched chain cannot penetrate. Therefore, urea crystals adsorb only hydrocarbons of normal structure from the mixture, which, after dissolving the urea, are separated from the aqueous layer.
In industry, urea is obtained from ammonia and carbon dioxide at 185 °C and pressure
Thiocarbamide Crystalline substance; temp, pl. 172°C. Easily soluble in water, slightly soluble in alcohol. Thiocarbamide can be prepared by the action of hydrogen sulfide on cyanamide
or by heating ammonium thiocyanate. Used to produce urea polymers.
Description. Solubility. White crystalline powder, odorless, salty-alkaline taste, soluble in water, practically insoluble in alcohol. Aqueous solutions have a slightly alkaline reaction. When shaking and heating aqueous solutions of NaHCO 3 to 70 o C, the double salt Na 2 CO 3 is formed · NaHCO3.
Receipt
Sodium bicarbonate was discovered in 1801 by the scientist V. Rose. The drug is prepared by saturating purified soda ash with carbon dioxide:
Na 2 CO 3 · 10 H 2 O + CO 2 → 2NaHCO 3 + 9 H 2 O
calcium dioxide drinking
Authenticity
In qualitative analysis, pharmacopoeial reactions are carried out for the Na + ion and HCO 3 - - ion.
General reactions to CO 3 2 - and HCO 3 - - ions:
Under the influence of a strong mineral acid, rapid release of CO 2 is observed:
NaHCO 3 + HCl → NaCl + H 2 O + CO 2
CO 2 + Ca(OH) 2 → CaCO 3 ↓ + H 2 O
lime dioxide white
carbon water
Distinctive reactions:
1) Carbonates can be distinguished from bicarbonates by the color of the indicator - phenolphthalein. When sodium carbonate is dissolved in water, the reaction of the medium is slightly alkaline and therefore the color of the indicator is pink: Na 2 CO 3 + H 2 O → NaHCO 3 + NaOH
When sodium bicarbonate is dissolved, the reaction of the medium is acidic, and the indicator is colorless or slightly pink: NaHCO 3 + H 2 O → H 2 CO 3 + NaOH
H 2 CO 3 → CO 2 + H 2 O
2) With a saturated solution of magnesium sulfate, carbonates form a white precipitate at room temperature, and bicarbonates - only when boiling:
4 Na 2 CO 3 + 4 MgSO 4 + 4 H 2 O → 3 MgCO 3 Mg(OH) 2 3 H 2 O↓ + 4 Na 2 SO 4 + CO 2
2 NaHCO 3 → Na 2 CO 3 + CO 2 + H 2 O
Goodness
NaHCO3: 1) allowed: Cl – , K + , Ca 2+ , Fe, As.
The specific admixture of CO 3 2– is determined by calcination at a temperature of 300 o C. The loss in mass must be at least 36.6%. The more carbonates there are, the less weight loss during ignition. The theoretical loss is 36.9%. The difference between the theoretical weight loss and that indicated in the Global Fund determines the permissible limit for carbonate impurities in the preparation - 0.3%.
2) not allowed: NH 4 + salts and heavy metals.
Quantification
Acidimetry, direct titration, the sample is dissolved in freshly boiled and cooled water to remove CO 2, titrated with 0.5 N HCl, methyl orange indicator. E = M.
Application. Storage.
Store in a well-closed container. The substance is stable in dry air, but in humid air it slowly loses CO 2 and forms Na 2 CO 3.
Apply as an antacid internally, as well as externally in the form of rinses, rinses, inhalations of 0.5 - 2% solutions.
Features of the preparation of NaHCO 3 injection solutions
NaHCO 3 injection solutions are sterilized at 100 o C for 30 minutes. In this case, CO 2 is formed, so bottles with an injection solution of NaHCO 3 are filled to 2/3 of the volume at a temperature of no more than 20 o C.
After sterilization, the solution is cooled until the resulting CO 2 is completely dissolved.
Description. Solubility. Colorless transparent crystals or white crystalline powder, odorless, slightly bitter taste. Sublimes and erodes. Slightly soluble in water, soluble in alcohol, slightly soluble in chloroform, ether, turpentine.
Receipt
Terpinhydrate obtained from pinene, a product of the fractional distillation of turpentine. Hydration of pinene is carried out under the action of sulfuric acid in the cold for 10 days. Then the mixture is neutralized with soda, the terpene hydrate is separated, purified and recrystallized.
Authenticity
General reactions
Drugs are identified postalcoholic hydroxyl:
1) reaction to form esters with acids. This property is used in the production of validol. When esterification of menthol and terpin hydrate with acetic anhydride, acyl derivatives are obtained in the form of a white precipitate; its melting point can be determined.
2) oxidation reaction. Menthol is oxidized by weak oxidizing agents to ketone-menthone. When exposed to strong oxidizing agents, menthol decomposes to formic, acetic, butyric and oxalic acids.
Specific reactions
Terpinhydrate when interacting with an alcohol solution of ferric chloride during the evaporation process, it forms carmine-red, violet and green colors in different places of the evaporation cup. When benzene is added to the oxidation products, a blue color is formed.
Terpene hydrate is also discovered by a dehydration reaction in the presence of concentrated sulfuric acid to produce turbidity and an aromatic odor:
Goodness
Terpinhydrate. 1) Allowed:
sulphate ash and heavy metals.
Carbonic acid chloride – phosgene:
Like all acid chlorides, phosgene has a high acylating ability:
Carbonic acid amides
1) Carbamic acid
Carbamic acid– semiamide (acid amide) of carbonic acid – unstable:
2) Urea
Urea– urea, carbonic acid diamide:
Urea is the most important end product of protein metabolism in mammals. An adult excretes 20-30 g of urea in urine per day.
Wöhler's synthesis (1828).
Industrial method for producing urea
Urea is a large-scale product of the chemical industry (world production is more than 100 million tons per year). It is widely used as a nitrogen fertilizer and for the production of urea-formaldehyde resins. In the chemical and pharmaceutical industry it is used to produce barbiturates.
Chemical properties urea
1) Basicity:
2) Decomposition when heated:
3) Decomposition by nitrous acid
By the amount of nitrogen released, urea can be quantitatively determined
(Van-Slyke method).
3) Guanidine
Guanidine has an unusually high basicity, comparable to that of inorganic alkalis. This is due to high degree structural symmetry of its protonated form and maximum delocalization of the (+) charge:
Guanidine residues are found in some natural compounds and medicinal substances, for example:
Sulfur in organic compounds has varying degrees of oxidation.
Thiols and thioesters
When replacing a halogen with an SH group, thiols are formed:
Thiols are more acidic than alcohols:
Thiolate anions are strong nucleophiles; when interacting with halogen derivatives, they form thioesters:
The sulfur atom in thioethers is the center of basicity and nucleophilicity; when interacting with halogen derivatives, thioethers form trialkylthionium salts:
Thiols in mild conditions easily oxidize, forming disulfides:
The direction of the reaction changes when
RH potential of the environment: with a high RH potential - to the right, with a low RH potential - to the left. Thiol-disulfide interconversions play an important role in the formation of the structure and regulation of the functions of natural proteins.
Sulfoxides and sulfones
During the oxidation of thioethers, a sulfur atom adds oxygen, and sulfoxides and sulfones are successively formed:
Dimethyl sulfoxide (DMSO, dimexide)- colorless liquid with boiling temperature. 189°C, soluble in water and organic solvents. Widely used in organic synthesis as a polar aprotic solvent.
Due to its ability to quickly diffuse through the skin, carrying substances dissolved in it, it is used in pharmacy as a component of medicinal ointments.
Sulfonic acids (sulfonic acids)
Sulfonic acids (or sulfonic acids) compounds containing sulfo group:
Methods for producing sulfonic acids
1) Aliphatic sulfonic acids
2) Aromatic sulfonic acids are obtained by sulfonation of benzene and its derivatives (see “Chemical properties of arenes”)
Chemical properties of sulfonic acids
Sulfo group –
1) strong electron acceptor;
2) she has high acidity(comparable to sulfuric acid);
3) when nucleophilic attack on a neighboring C-atom can be replaced for other leftovers.
4) High polarity and ability to hydrate is the reason solubility sulfonic acids in water.
1) Acidity
In an aqueous environment, sulfonic acids are almost completely ionized:
With alkalis they form water-soluble salts:
2) Replacement of the sulfo group with other residues
3) Formation of derivatives at the sulfo group
Carbonic acid, like many other acids, forms a number of derivatives: salts, esters, chlorine anhydrides, amides, etc.
Carbonic acid amides are of great interest for medicine, since their derivatives are valuable medicines.
Carbonic acid, as a dibasic acid, forms two types of amides: a) incomplete amide (the product of substitution of one hydroxyl with an amino group) - carbamic acid; b) full
amide (product of substitution of two hydroxyls with amino groups) - carbamide, or urea.
Carbamic acid in the free state is unknown due to its high tendency to decompose into carbon dioxide and ammonia. But its acid chlorides, salts, and esters are well known. Carbamic acid esters, called urethanes, which have a hypnotic effect, are important for medical practice.
Depending on the nature of the alcohol with which carbamic acid is esterified, various urethanes can be obtained.
Of the urea derivatives, the greatest interest for medicine is its acyl derivatives, in which the hydrogen of the amino group of urea is replaced by an acid residue - acyl (Ac - the residue of any acid).
Acyl derivatives of urea were first obtained by N. N. Zinin and were named ureides by him.
When urea reacts with a monobasic carboxylic acid, open (acyclic) ureides are formed.
When urea reacts with a dibasic carboxylic acid, both open and closed (cyclic) ureades can be obtained, depending on the reaction conditions.
By replacing the hydrogens in the methylene group (position 5) of the barbituric acid molecule with various radicals, one can obtain many of its derivatives (barbiturates), which are used in medicine as hypnotic drugs.
According to their physical properties, drugs related to ureides and urethanes are solid crystalline substances white, sparingly soluble in water, with the exception of salts.
The chemical properties of ureides and urethanes have a number of common features - when heated with alkali, both release ammonia and sodium carbonate; when acidified, sodium carbonate releases gas bubbles (CO2).
Other reaction products in the interaction of urethanes and ureides with alkali make it possible to distinguish them from each other.
In the case of urethanes, alcohol (I) is formed, in the case of ureides, the iatrium salt of the corresponding acid (II).
One of the representatives of urethanes is the drug meprotane; among the discovered ureides, bromizoval is used in medicine.
Application. Storage.
Quantification
Goodness
Authenticity
Receipt
Iron supplements
Application. Storage.
Store in a well-closed container, in a cool place, since sodium tetraborate can lose water of crystallization and hydrolyze to form boric acid:
Na 2 B 4 O 7 + 7 H 2 O ® 4 H 3 BO 3 ↓ + 2NaOH
Boric acid does not require special storage conditions.
Apply preparations as antiseptics for external use. Boric acid used in the form of 2–3% solutions for gargling, in the form of glycerin solutions, ointments, powders. 1–2% solutions are used in ophthalmic practice. Boron compounds are poisonous, so they are not used internally. Borax is used in the form of 1–2% solutions.
Description. Solubility. Prismatic transparent crystals of light bluish-green color or crystalline pale green powder. Soluble in water, solutions of slightly acidic reaction. It erodes in the air.
Excess reduced iron is dissolved in a 30% sulfuric acid solution at t o = 80 o C: Fe + H 2 SO 4 ® FeSO 4 + H 2
The solution is evaporated, the preparation is dried at t o = 30 o C.
Pharmacopoeial reactions are carried out on iron ions and sulfate ions.
1) Fe 2+: Reaction of formation of Turnbull's blue:
FeSO 4 + K 3 + H 2 SO 4 ® FeK ¯ + 2 K 2 SO 4
Reaction with alkali and ammonia solutions:
· FeSO 4 + NaOH + NH 4 OH ® Fe(OH) 2 ¯ + O 2 air. ® Fe(OH) 3 ¯
white brown
Sulfide precipitation reaction:
FeSO 4 + Na 2 S ® FeS ¯ + Na 2 SO 4
2) SO 4 2-: FeSO 4 + BaCl 2 ® BaSO 4 ¯ + FeCl 2
1) acceptable: heavy metals, As.
2) unacceptable: copper salts are opened by adding H 2 O 2 and NH 4 OH, then the resulting precipitate is filtered off; The filtrate should be colorless.
Permanganatometry, direct titration. The method is based on the oxidation of Fe(II) with potassium permanganate in an acidic environment to Fe(III). E = M.
10 FeSO 4 + 2 KMnO 4 + 8 H 2 SO 4 ® 5 Fe 2 (SO 4) 3 + K 2 SO 4 + 2 MnSO 4 + 8 H 2 O
Store in a well-closed container, in a dry place, avoiding loss of water of crystallization and oxidation in humid air with the formation of the main salt Fe 2 (OH) 4 SO 4. At 64 o C, iron sulfate melts in its crystalline water.
Apply ferrous sulfate in the complex therapy of iron deficiency anemia in the form of tablets and injection solutions. Prescribe 0.05–0.3 g per dose.
Carbonic acid forms two types of salts: medium - carbonates and acidic - hydrocarbonates.
| NaHCO3 | Sodium hydrocarbonate Natrii hydrocarbonas |
Description. Solubility. White crystalline powder, odorless, salty-alkaline taste, soluble in water, practically insoluble in alcohol. Aqueous solutions have a slightly alkaline reaction. When shaking and heating aqueous solutions of NaHCO 3 to 70 o C, the double salt Na 2 CO 3 is formed · NaHCO3.