Structural formula
True, empirical, or gross formula: CH 2 O 2
Muravic acid chemical composition
Molecular weight: 46,025
Formic acid (Systematic Name: Methanic Acid) - First Representative in a series of saturated monosocondary carboxylic acids. Registered as a dietary supplement under the designation E236. The formic acid has received its name because it was first highlighted in 1670 by English naturalist John Rayem in red forest ants. In nature, also found at bees, in nettle, needle.
Formula: HCOOH
Physical and thermodynamic properties
Under normal conditions, formic acid is a colorless liquid. Soluble in acetone, benzene, glycerin, toluene. Mixed with water, diethyl ether, ethanol.
Obtaining
- Bypass product in the production of acetic acid with liquid-phase oxidation of butane.
- Oxidation of methanol
- Carbon monoxide reaction with sodium hydroxide: NaOH + CO → HCOONA → (+ H 2 SO 4, -NA 2 SO 4) HCOOH is the main industrial method, which is carried out in two stages: in the first stage of carbon monoxide under pressure 0.6-0 , 8 MPa is passed through a sodium hydroxide heated to 120-130 ° C; In the second stage, sodium formate is treated with sulfuric acid and vacuum distillation of the product.
- Decomposition of glycerin esters of oxalic acid. For this, the anhydrous glycerin with oxalic acid is heated, while the water is distilled off and the oxal ethers are formed. With further heating, the ethers are decomposed, highlighting carbon dioxide, while forming ethers are formed, which, after decomposition, water is given to formic acid and glycerin.
Safety
The danger of formic acid depends on the concentration. According to the classification of the European Union, the concentration of up to 10% has an irritant effect, more than 10% by corrosive. When contacting the skin, 100% liquid formic acid causes severe chemical burns. Even the small amount of its skin hurts a strong pain, the affected area first whites, as if covered by it, then it becomes like wax, a red border appears around it. Acid easily penetrates through the fat layer of the skin, so the washing of the affected area with a solution of soda must be made immediately. Contact with concentrated vapors of formic acid may damage the eye and respiratory tract. Random hitting even dilute solutions causes the phenomena of severe necrotic gastroenteritis. Formic acid is rapidly recycled and excreted by the body. Nevertheless, formic acid and formaldehyde formed by methanol poisoning cause damage to the optic nerve and lead to blindness.
Chemical properties
Dissociation constant: 1.772 · 10 -4. Formic acid, in addition to acidic properties, also exhibits some properties of aldehydes, in particular, restorative. At the same time it is oxidized to carbon dioxide. For example:
2kmno 4 + 5hCooh + 3H 2 SO 4 → K 2 SO 4 + 2MNSO 4 + 5CO 2 + 8H 2 O
When heated with strong water-based means (H 2 SO 4 (conc.) Or P 4 O 10) decomposes into water and carbon monoxide: HCOOH → (T) CO + H 2 O formic acid reacts with an ammonium solution of silver oxide HCOOH + 2OH - -\u003e 2Ag + (NH 4) 2CO 3 + 2NH 3 + H 2 O The interaction of formic acid with sodium hydroxide. HCOOH + NaOH \u003d HCOONA + H 2 O
Finding in nature
In nature, formic acid is found in needles, nettle, fruits, caustic discharges of jellyfish, bees and ants. Formic acid was first highlighted in 1670 by English naturalist John Rayem from red forest ants than and the name is explained. In large quantities, formic acid is formed as a by-product with liquid-phase oxidation of butane and a light gasoline fraction in the production of acetic acid. Formic acid is also obtained by hydrolysis of formamide (~ 35% of the total world production); The process consists of several stages: methanol carbonylation, the interaction of methyl formate with anhydrous NH 3 and the subsequent hydrolysis of the formamide formed 75% H 2 SO 4. Sometimes a direct hydrolysis of methyl formate is used (the reaction is carried out in an excess of water or in the presence of a tertiary amine), the hydration of CO in the presence of a rubble (the acid is isolated from salt by the action H 2 SO 4), the dehydrogenation of CH 3 in the steam phase in the presence of catalysts containing as well Zr, Zn, Cr,, Mg, etc. (method has no industrial value).
Application
Derivatives of formic acid
The salts and ethers of formic acid are called formates.
Many of us have heard of such products of the chemical industry as formic acid, however, few people guess, in which areas of human livelihoods it is used. But this is a true participant in many industrial processes in textile and food industries. Apply it in medicine, as well as for many cosmetic procedures.
Natural sources of this universal means are: some plants, fruits, bees and directly the ants themselves, however, it can be obtained quite a bit, therefore it is produced in large quantities by synthesis and is the products of the chemical industry.
Properties of formic acid
Formic acid can be found on the ridiculous smell. This is a colorless liquid, the second name of which can be found on many packs with food, because this is a nutritional supplement E236. As mentioned, formic acid is used in many spheres of human activity, namely:
However, it is necessary to treat it very carefully, since it is still acid, which in 100% concentrations can cause burns when entering skin cover, and in the case of inhalation of its vapor, serious damage to the respiratory tract and organs of vision. If formic acid falls inside, even in a diluted form, it can cause serious problems with stomach, right up to gastritis.
Application of formic acid in medicine
One of the main properties for which this tool appreciates is its disinfecting effect. Therefore, it is used to treat many diseases:
- Problems with joints (arthritis, arthrosis, inflammatory processes, etc.)
For the treatment of varicose. - When obtaining various injuries, for example, stretching or hematoma.
- With viral diseases, or if the reason was the fungus.
- For the treatment of acne.
- When treating from tuberculosis, the tool is used as an immunostimulator.
- It is used as. It can be found in the pharmacy, in the form of a solution, such a drug is called ant alcohol. In addition, it is added to the composition of various gels, ointments, balms and creams. These drugs are used mainly for outdoor use, in rubbing, rims and in the process of massage. ethnoscience Applies an ointment based on the agent of hematomas and bruises.
Formic acid is contraindicated in case there are wounds or other skin damage, it is also better to refuse to use it if there is hypersensitivity to the preparation.
What is needed formic acid in cosmetology
As part of cosmetic products, it is used to treat acne. In this area of \u200b\u200bher antiseptic properties It has long been appreciated and use most often. It not only disinfects, but also eliminates inflammatory processes, promotes skin cleansing. These of its features allow formic acid to successfully combat even the most severe cases. This means It is also used to remove unwanted hair removal and as a rigging aid.
For acne treatment
In an effort to get rid of the acne rash it is better to choose a solution of formic acid - ant alcohol (70%). It can be used as a lotion, wipes them a face a couple of times a day, moishable in the composition of a cotton disk. However, in the application of this drug treatment, there is a pair of nuances:
- The remedy is not suitable for dry and sensitive skin, because it strongly overwhelms it.
- Before using it, it is better not to carry out any cleansing procedures, and do not use detergents.
It is recommended to handle the skin with antirex alcohol with a softer effect. In addition, after the procedure, you need to use the cream with a moisturizing effect. The duration of the course may take from a pair of weeks to several months, until the result satisfies completely.
To remove unwanted hair
A formic acid is used to remove unwanted hair cover at home, although it is more precise, here also uses a means not in pure form, but so-called ant oil. It is produced in the countries of Eastern and Central Asia, and it acts detrimental to hair growth, significantly slowing it, and after a long use, eliminates them at all, destroying hair bulbs.
For Tan
Formic acid is a participant in the composition of a special tan cream, which is used in the solarium. It plays the role of a warming element, thanks to which, it turns out a more even, saturated and persistent color, and the exchange processes in the skin are improving.
What is useful to formic acid in beekeeping
Video: Processing bees from a tick
More specifically how to use formic acid in beekeeping for processing bees from a tick can be found from the video below:
The interaction of formic acid with ammonia solutionsilver hydroxide(silver mirror reaction). There is an aldehyde group in the formic acid molecule, therefore, it is possible to open it in solution with reactions characteristic of aldehydes, such as a silver mirror reaction.
Prepare in the test tube an ammonium solution of argene (ι) hydroxide. To do this, 1 to 1 - 2 ml of a 1 percent solution of argene (ι) of nitrate is added 1 to 2 drops of a 10% sodium sodium solution, the resulting precipitate of the argene (ι) of the oxide is dissolved by adding a 5% ammonia solution dropwise. 0.5 ml of formic acid is added to the resulting transparent solution. The tube with the reaction mixture is heated for several minutes in the water bath (water temperature in the bath 60 0 -70 0 s). Metallic silver is highlighted in the form of a mirror plate on the walls of the test tube or in the form of a dark precipitate.
Nson + 2AG [(NH 3) 2] He → CO 2 + H 2 O + 2AG + 4NH 3
b) Oxidation of formic acid potassium permanganate.Approximately 0.5g formic acid or its salt, 0.5 mR of a 10 percent solution of sulfate acid and 1 ml of a 5 percent solution of potassium permanganate was placed in the tube. The tube is closed with a plug with a gas-conductive tube, the end of which is lowered into another tube with 2 ml of lime (or barite) water, and heated the reaction mixture.
5nson + 2kmno 4 + 3H 2 SO 4 → 5CO 2 + 8H 2 O + K 2 SO 4 + 2MNSO 4
in) Decomposition of formic acid when heated withconcentrated sulfuric acid. (Thrust!)1 ml of formic acid or 1 g of its salt and 1 ml of concentrated sulfate acid are brought into the dry tube. The tube is closed with a plug with a gauge tube and carefully heated. Formic acid decomposes with the formation of carbon (II) oxide and water. Carbon (II) oxide ignites the opening of the gas pipe. Pay attention to the nature of the flame.
After the end of operation, the test tube with the reaction mixture must be cooled to stop the selection of poisonous carbon monoxide gas.
Experience 12.. The interaction of stearin and oleic acids with alkali.
In a dry tube, approximately 0.5 g of stearin in diethyl ether (without heating) is dissolved and 2 drops of 1 percent alcohol phenolphthalene alcohol solution are added. Then, a 10% sodium hydroxide solution is across drops. The emerging criminal color disappears when shaking.
Write a stearic acid reaction equation with sodium hydroxide. (Steaarin is a mixture of stearin and palmitic acids.)
From 17 H 35 COOH + NaOH → 17 H 35 Coona + H 2 O
sodium Stearat
Repeat experience using 0.5 ml of oleic acid
From 17 H 33 COOH + NaOH → 17 H 33 Coona + N 2
sodium oleate
Experience13. The ratio of oleic acid to bromine water and a solution of potassium permanganate.
but) Oleic acid reaction with bromine water2 ml of water is poured into the tube and about 0.5 g of oleic acid contribute. The mixture is vigorously shaken.
b) Oxidation of Oleic acid potassium permanganate.A 1 ml of a 5% solution of potassium permanganate was placed in the tube, 1 ml of a 10% sodium carbonate solution and 0.5 ml of oleic acid. The mixture is vigorously stirred. The changes occurring with the reaction mixture are noted.
Experience 14.. Renaic acid sublimation.
The sublimation of small amounts of benzoic acid leads in a porcelain cup closed with a wide end of the conical funnel (see Fig. 1), the diameter of which is somewhat less than the diameter of the cup.
The spout of the funnels is fixed in the footage of the tripod and close tightly with cotton, and in order for the occasion to come back into a cup, it is covered with a round sheet of filter paper with several holes in it. A porcelain cup with small benzoic acid crystals (T pl \u003d 122.4 0 s; it is removed below T pl) carefully slowly heat on a small flaregas burner (on the asbesto net). You can cool the upper funnel, applying a piece of filter paper moistened with cold water. After the extraction of the sublimation (after 15-20 minutes), the sublimates are cautioned by a spatula into a flask.
Note. For work, benzoic acid can be contaminated.
The test tube in which the emulsion was formed is closed with a reflux tube, heated in a water bath to beginner boiling and shake. Is oil solubility increase when heated?
Experience is repeated, but instead of sunflower oil in test tubes with organic solvents, a small amount of animal fat (pork, beef or ladder salary) is made),
b) Determination of the degree of fatality of fat reaction with brominewater. (Thrust!)A 0.5 ml of sunflower oil and 3 ml of bromine water poured into the tube. The contents of the test tube are vigorously shaken. What happens to bromine water?
in) The interaction of vegetable oil with an aqueous solution of potassiumpermanganate (reaction E. E. Wagner).Approximately 0.5 ml of sunflower oil is poured into the tube, 1 ml of a 10% sodium carbonate solution and 1 ml of a 2 percent solution of potassium permanganate. Vigorously shake the contents of the test tube. Purple coloring potassium permanganate disappears.
The discoloration of bromine water and the reaction with an aqueous solution of potassium permanganate - high-quality reactions to the presence of multiple bond (unsaturation) in the organic matter molecule.
d) Outlet of fat with alcohol sodium hydroxide1.5 - 2 g of solid fat are placed in the conical flask with a capacity of 50 - 100 ml and 6 ml of 15% alcohol sodium hydroxide sodium solution is adhered. The flask is closed with a tube with an air refrigerator, stirred the reaction mixture and heated the flask in the water bath when shaking for 10-12 minutes (the temperature of the water in the bath is about 80 0 s). To determine the end of the reaction, several drops of hydrolyzate are poured into 2-3 ml of hot distilled water: if the hydrolyzate dissolves completely, without selection of the fat droplets, then the reaction can be considered complete. After the end of the washed from the hydrolyzate, the soap is smelted by adding 6 to 7 ml of hot saturated sodium chloride sodium solution. The released soap pops up, forming a layer on the surface of the solution. After settling, the mixture is cooled with cold water, the solidified soap is separated.
The chemistry of the process on the example of tristearin:
Experience 17. Comparison of soap properties and synthetic detergents
but) Attitude to phenolphthalene.Pour into one tube 2-3 ml of 1 percent solution of the economic soap, to another - as much as a 1 percent solution of synthetic washing powder. Add 2-3 drops of phenolphthalein solution to both test tubes. Is it possible to use these detergents for washing fabrics sensitive to alkalis?
b) Attitude towards acids.To solutions of soap and washing powder in test tubes, add as far as drops of a 10 percent solution of an acid (chloride or sulfate). Is the foam formed when shaking? Are the washing properties of the investigated funds in an acidic environment persist?
C 17 H 35 Coona + HCl → C 17 H 35 COOH ↓ + NaCl
in) Attitudetocalcium chloride.To the solutions of soap and washing powder in tubes are added by 0.5 ml of a 10% solution of calcium chloride. Shake the contents of the tubes. Is the foam forms? Is it possible to use these tools for washing in rigid water?
C 17 H 35 Coona + CaCl 2 → Ca (C 17 H 35 COO) 2 ↓ + 2NACL
Experience 18 . The interaction of glucose with ammonium solution of Argentum (ι) oxide (silver mirror reaction).
The tube poured 0.5 ml of 1 percent solution of argentum (ι) nitrate, 1 ml of a 10% sodium hydroxide solution and a 5-percent solution of ammonia ammonia to dissolve the formed precipitate of the Argentum (ι) of hydroxide. Then add 1 ml of a 1 percent glucose solution and the contents of the tube 5-10 min in the water bath at 70 0 - 80 0 C are heated at 70 0 - 80 0 C. Metal silver is highlighted on the walls of the test tube in the form of a mirror plate. During heating, the test tubes cannot be shaken, otherwise the metallic silver is separated on the walls of the tubes, but in the form of a dark precipitate. To get a good mirror, a 10% solution of sodium hydroxide is pre-boiled in test tubes, then they are rinsed with distilled water.
A 3 ml of 1 percent solution of sucrose is poured into the tube and 1 ml of a 10% sulfuric acid solution is added. The resulting solution is boiled for 5 minutes, then cooled and neutralized by dry sodium bicarbonate, adding it in small portions with stirring (carefully, the liquid is foaming from the released carbon oxide (IY)). After neutralization (when the selection of CO 2 stops), equal to the volume of Feling reagent and heated top Fluids up to starting boiling.
Does the color of the reaction mixture change?
A mixture of 1.5 ml of 1 percent solution of sucrose with equal volume of Feling reagent is heated in another test tube. Compare the results of experience - the reaction of sucrose with the feling reagent to hydrolysis and after hydrolysis.
From 12 N 22 O 11 + N 2 O C 6N 12 O 6 + C 6H 12 O 6
glucose fructose
Note. In the conditions of the school laboratory, Feling reagent can be replaced by the dumplings (ιι) by hydroxide.
Experience 20. Hydrolysis of cellulose.
In a dry conical flask with a capacity of 50 - 100 ml, a little very finely chopped pieces of filter paper (cellulose) are placed and wet them with concentrated sulphate acid. Thoroughly mix the contents of the flask with a glass stick until the paper and the formation of a colorless viscous solution. After that, it is added to it in small portions with stirring 15 - 20 ml of water (carefully!), The flask is connected to the air reflux and boil the reaction mixture of 20 to 30 minutes, stirring it periodically. After the end of the hydrolysis, 2-3 ml of liquids are cast, it is neutralized by dry sodium carbonate, adding it in small portions (the liquid is foaming), and the presence of regenerating sugars react with the feling reagent or downturn (ιι) hydroxide is detected.
(C 6 H 10 O 5) N + NH 2 O → NC 6 H 12 O 6
Cellulose glucose
Experience 21. The interaction of glucose with dumplings (ιι) hydroxide.
a) 2 ml of 1 percent glucose solution and 1 ml of 10 percent sodium hydroxide are placed in the tube. 1- 2 drops of a 5% solution of sulfate can be added to the mixture obtained and the contents of the test tube shake. Forming at the beginning of a bluish precipitate to the dumping (ii) of the hydroxide instantly dissolves, the blue transparent solution is obtained by the KUPU (ιι) of the Saharat. Process chemistry (simplified): - 
b) The contents of the test tubes are heated above the flame of the burner, the test tube is obligated so that only the upper part of the solution is heated, and the lower left without heating (for control). With careful heating to a boil, the heated part of the blue solution is painted in orange-yellow color due to the formation of the dock (ι) of hydroxide. With a longer heating, a precipitate can be formed by dumping (ι) oxide.
Experience 22.The interaction of sucrose with metals hydroxides. but) Reaction with dump (ιι) hydroxide) in an alkaline medium.The tube mixes 1.5 ml of 1 percent sucrose solution and 1.5 ml of a 10% sodium hydroxide solution. Then a 5 percent solution of dumplings (ιι) of sulfate is added dropwise. Folding at the beginning of a pale blue precipitate (ιι) of hydroxide during shaken dissolves, the solution acquires a blue-purple color due to the formation of a comprehensive dumplings (ιι) of the Saharat.
b) Obtaining calcium sacharata.In a small glass (25 - 50 ml) poured 5 - 7 ml of a 20 percent solution of sucrose and freshly prepared lime milk adds to stirring. Calcium hydroxide is dissolved in sucrose solution. The ability of sucrose to produce soluble calcium saharats is used in industry to clean sugar when highlighting it from sugar beet. in) Specific color reactions.Two tubes poured 2 to 5 ml of a 10% sucrose solution and 1 ml of 5% sodium hydroxide solution. Then a few drops add to one test tube. 5- percent solution cobalt (ιι) sulfate, to another - a few drops 5- nickel percent solution (ιι) sulfate. Violet staining appears in the tube with a salt of cobalt, and with salt of nickel - green, experience2z. The interaction of starch with iodine. A 1 ml of 1-percent solution of starchy celatier is poured into the tube and then several drops of a strongly diluted with iodine water in potassium iodide are added. The contents of the test tube are painted in blue. The resulting dark blue liquid is heated to a boil. The coloring disappears, but when cooling appears again. Starch is an inhomogeneous compound. It is a mixture of two polysaccharides - amylose (20%) and amylopectin (80%). Amilose soluble in warm water and gives blue staining with iodine. Amilose consists of almost undiscorded chains of glucose residues with the structure of the screw or helix (approximately 6 glucose residues in one screw). Inside the helix remains a free channel with a diameter of about 5 MK, which introduces iodine molecules, forming painted complexes. When heated, these complexes are destroyed. Amylopectin in warm water will not soluble, swelling in it, forming starchy holter. It consists of branched chains of glucose residues. Amopectin with iodine gives reddish-purple staining caused by the adsorption of iodine molecules on the surface of the side chains. Experience 24.Hydrolysis starch. but) Acid hydrolysis starch.In the conical flask, a capacity of 50 ml is poured 20 to 25 ml of 1 percent starch tire and 3-5 ml of a 10% sulphate acid solution. In 7 - 8, tubes poured 1 ml of a very diluted iodine solution in potassium iodide (light yellow color), test tubes put a tripod. 1 - 3 drops prepared for the experience of starch prepared for experience. Celebrate the resulting color. Then the flask is heated on the asbestos mesh with a small flame of the burner. After 30 seconds, after the start of the boiling, the second sample of the solution is taken by a pipette, which is made to the second test tube with iodine solution, after shaking the color of the solution. In the future, the samples of the solution are taken every 30 seconds and contribute to the subsequent tubes with iodine solution. The gradual change in the color of the solutions during the reaction with iodine is noted. Change coloring occurs in the following order, see Table.
After the reaction mixture stops giving coloring with iodine, the mixture is boiled 2 more - z min after which it is cooled and neutralized with 10% sodium hydroxide solution, adding it dropwise to an alkaline reaction of the medium (the appearance of pink color on phenolphthalene indicator paper). The portion of the alkaline solution is transferred to the tube, mixed with an equal volume of feling reagent or a freshly prepared suspension of the duct (ιι) of the hydroxide and heated the upper part of the fluid to the starting boiling.
(
Soluble
Dextry
C 6 H 10 O 5) N (C 6 H 10 O 5) X (from 6 H 10 O 5) Y
maltose
n / 2 from 12 H 22 O 11 NC 6 H 12 O 6
b) Enzymal starch hydrolysis.
A small piece of black bread is well chew and put it in a test tube. There are several drops of 5 percent solution to the dumplings (ιι) of sulfate and 05 - 1 ml of a 10% sodium hydroxide solution. The test tube with content is heated. 3. Technique and methods of demonstration experiments on obtaining and studying the properties of nitrogen-containing organic substances.
Equipment: Chemical glasses, glass wand, test tubes, flask Washer, drip funnel, chemical glass, glass gas-rod tubes, connecting rubber tubes, rauchinka.
Reagents: aniline, methylamine, Lacmus solutions and phenolphthalein, concentrated chloride acid, hydroxide sodium solution (10%), solution of chlorine lime, concentrated sulfate acid, concentrated nitrate acid, egg protein, solution of copper sulfate, plumbum (ιι) acetate, phenol solution , Formalin.
Experience 1.. Getting methylamine. In the flask of Würz, a volume of 100 - 150 ml to make 5-7 g of methylamine chloride and close the trough with the drip funnel inserted into it. Gauge tube to connect the rubber tube with a glass tip and omit into a glass with water. From the funnel drops to add potassium hydroxide solution (50%). The mixture in the flask gently heat. The decomposition of the salt and the release of methylin, which is easy to recognize the characteristic odor, which resembles the smell of ammonia. Methyline is assembled at the bottom of the glass under the water layer: + Cl - + Koh → H 3 C - NH 2 + KCl + H 2 O
Experience 2. The burning of methylamine. Methyline in the air burns with a colorless flame. To the hole of the gas pipeline of the device described in the previous experiment, bring the burning beam and observe the combustion of methylamine: 4H 3 C - NH 2 + 9O 2 → 4CO 2 +10 H 2 O + 2N 2
Experience 3. The ratio of methylamine to indicators. The obtained methylamine skip into a test tube filled with water and one of the indicators. Lacmus shines, and phenolphthalein becomes raspberry: H 3 C - NH 2 + H - OH → OH This indicates the main properties of methylamine.
Experience 4.Methylamine salts formation. a) to the hole of the tube from which the methylamine gas is distinguished, the glass wand moistened with concentrated chloride acid is made. The wand is enveloped with fog.
H 3 C - NH 2 + HCl → + Cl -
b) In two tubes poured 1 to 2 ml: in a single-s-percent solution of ferum (III) chloride, to another 5-percent solution of dumplings (ιι) sulfate. Methhylamine gas is passed into each tube. In the tube with a solution of ferum (III) chloride, a brown precipitate falls out, and a sulfate sulfate sulfate formed at the beginning of a blue collar solution (ιι) is dissolved at the beginning of a blue sediment dissolves to form a complex salt painted in bright blue color. Chemical process:
3 + OH - + FECL 3 → FE (OH) ↓ + 3 + Cl -
2 + OH - + Cuso 4 → Cu (OH) 2 ↓ + + SO 4 -
4 + OH - + Cu (OH) 2 → (OH) 2 + 4H 2 O
Experience 5.. Interaction of aniline with chloride acid. In the test tube S. 5 ml anilin pour as much concentrated chloride acid. Cool tube in cold water. The elevation of aniline hydrogen chloride falls. In the tube with solid hydrogen chloride aniline pour some water. After stirring, aniline hydrogen chloride dissolves in water.
C 6 H 5 - NH 2 + HCl → CL - Experience 6. Interaction of aniline with bromine water. To 5 ml of water pour 2 -z drops of aniline and the mixture shake strongly. To the resulting emulsion drops to add bromine water. The mixture is discolored, and a white precipitate of tribromaniline falls.
Experience7. Fabric painting aniline dye. Drain of wooland silk with acid dyes.Dissolve 0.1 g of methyl orange in 50 ml of water. The solution is spilled in 2 glasses. One of them add 5 ml of 4N sulfate acid solution. Then in both glasses omit the pieces of white wool (or silk) fabric. Fabric solutions boiled 5 minutes. Then the fabric is removed, washed with water, squeeze and dried in air, waving on glass chopsticks. Pay attention to the difference in the intensity of the color of the tissue pieces. How does the acidity of the medium on the color of the fabric color affect?
Experience 8.. Proof of the availability of functional groups in amino acid solutions. a) detection of the carboxyl group. To 1 ml of a 0.2% sodium solution of hydroxide painted with phenolphthalene in pink color, add dropwise 1 - a percentage solution of aminoacetate acid (glycine) to bleaching mixture HOOC - CH 2 - NH 2 + Naoh → Naooc - CH 2 - NH 2 + H 2 O b) Detection of an amino group. To 1 ml of 0.2% - a solution of chloride acid, painted by the Congo indicator into blue (acidic medium), add dropwise 1 percent solution of glycine before changing the color of the mixture to the pink (neutral environment):
HOOC - CH 2 - NH 2 + HCL → CL -
Experience 9.. AMINO acid action on indicators. In the test tube to make 0.3 g of glycine and add 3 ml of water. The solution is pouring into three test tubes. Add 1 - 2 drops of methylovant, to the second - the same solution of phenolphthalein, to the third - a solution of a lacmus. The color of the indicators does not change, which is explained by the presence in the glycine molecule acid (-son) and the main (-NH 2) groups that are mutually neutralized.
Experience 10.Deposition of proteins. a) in two test tubes with a squirrel solution add dropwise solutions of copper sulfate and plumbum (ιι) acetate. Flames are formed, dissolving in excess solutions of salts.
b) in two tubes with a protein solution add equal volumes of phenol solutions and formalin. Observe protein precipitation. c) Heat the protein solution in a burner flame. Observe the clouding of the solution, which is due to the destruction of hydrate shells near the protein particles and the increase in them.
Experience 11.. Color reactions of proteins. a) xanthoprotein reaction. To 1 ml of protein add 5- 6 drops of concentrated nitrate acid. When heated, the solution and the precipitate is painted in bright yellow color. b) Buret reaction. K 1 - 2 ml of protein solution add as many diluted solutions of copper sulfate. The liquid is painted in red-purple color. A buret reaction makes it possible to reveal a peptide connection in the protein molecule. The xanthoprotein reaction occurs only if the protein molecules contain the residues of aromatic amino acids (phenylalanine, tyrosine, tryptophan).
Experience 12. Reactions with carbamide. but) The solubility of urea in water.In the test tube are placed 0,5 g crystalline urea and gradually add water to complete dissolution of urea. The drop of the resulting solution is applied to the red and blue lactium paper. What reaction (acid, neutral or alkaline) has an aqueous solution of urea? In aqueous solution, urea is in the form of two tautomeric forms:
b) Hydrolysis of urea.Like all acid amides, urea is easily hydrolyzed in acidic and in alkaline media. 1 ml of 20 percent urea solution is poured into a test tube and 2 ml of transparent barite water is added. The solution boils to the appearance of a carbonate barrium precipitate in the test tube. The ammonia released from the test tube is detected by the formation of a damp lactium paper.
H 2 N - C - NH 2 + 2H 2 O → 2NH 3 + [HO - C - OH] → CO 2
→ H 2 o 
Ba (OH) 2 + CO 2 → Baco 3 ↓ + H 2 O
c) Biuret's education.In the dry tube heated 0,2 g urea. At first, the urea melts (at 133 s), then with further heating decomposes with the separation of ammonia. Ammonia detect the smell (Caution!)and according to the formation of a wet red lactium paper, brought to the hole of the test tube. After some time, the melt in the test tube hardens, despite the continuing heating:
The test tube is cooled, added to it 1 -2 ml of water and with weak heating dissolve biuret. In the melt, except for biuret, there is a certain amount of cyanuric acid hard-soluble in water, so the solution is muddy. When the precipitate is dismissed, the biuret solution is drained into another tube, several drops of a 10% sodium solution of sodium hydroxide are added (while the solution becomes transparent) and 1-2 drops of a 1 percent solution of dumplings (ιι) sulfate. The solution is painted in pink-purple color. Excess carp (ιι) sulfate masks characteristic staining, causing a solution to the solution, so it should be avoided.
Experience 13. Functional analysis of organic substances. 1. Qualitative elemental analysis of organic compounds. The most common elements in organic compounds, except carbon, are hydrogen, oxigen, nitrogen, halogens, sulfur, phosphorus. Conventional methods of high-quality analysis are not applicable to analyzing organic compounds. To detect carbon, nitrogen, sulfur and other elements, the organic substance is destroyed by fusion with sodium, while the studied elements go into inorganic connections. For example, carbon enters carbon (I) oxide, hydrogen - into water, nitrogen - in sodium cyanide, sulfur - in sodium sulfide, halogens - in sodium halides. Next, open elements with conventional methods of analytical chemistry.
1. Detection of carbon and hydrogen by the oxidation of the substance can be kept (II) oxide.
The device for the simultaneous detection of carbon and hydrogen in the organic matter:
1 - dry tube with a mixture of sucrose and dumplings (II) oxide;
2 - test tube with lime water;
4 - anhydrous kupper (ιι) sulfate.
The most common, universal method of detection in the organic matter. Carbon and at the same time with it hydrogen is the oxidation of the dumplings (II) oxide. In this case, carbon is converted to carbon (I) oxide, and hydrogen - into water. In a dry tube with a gas-conductive tube (Fig. 2) placed 0.2 - 0.3 g of sucrose and 1 - 2 g of powder Kooch (II) oxide. The contents of the test tubes are thoroughly stirred, the mixture is covered with a layer of dumping (II) oxide. - approximately 1 g. In the upper part of the test tube (under the cork), a small piece of watts is placed on which is poured a bit of anhydrous copper sulfate (II). The tube is closed with a plug with a gas-conductive tube and fix it in a tripod foot with a slight tilt toward traffic jams. The free end of the gas feed tube is lowered into a test tube with limestone (or barite) water so that the tube almost touched the surface of the fluid. First heat the entire test tube, then the part is very heated, where the reaction mixture is. Mark what happens with lime water. Why is the color of the dumplings (ιι) of sulfate?
Chemistry of processes: C 12 H 22 O 11 + 24CUO → 12CO 2 + 11H 2 O + 24CU
Ca (OH) 2 + CO 2 → Caco 3 ↓ + H 2 O
CUSO 4 + 5H 2 O → CUSO 4 ∙ 5H 2 O
2. Bailesti sampleon halogens.When calculating the organic matter with dumplings (II), oxide occurs its oxidation. Carbon turns into carbon (ІU) oxide, hydrogen - in the water, and halogens (except for fluor) form with the downtime of volatile halides, which paint the flame in bright green. The reaction is very sensitive. However, it should be borne in mind that some other bases of dumplings, such as cyanides formed by calcining nitrge-containing organic compounds (urea, pyridine derivatives, quinoline, etc.), also color the flame. The copper wire is kept behind the plug and calcinate the other end of it (loop) in the burner flame to stop staining the flame and formation on the surface of the black plaque to the oxide (II) surface. The cooled loop is wetted by chloroform, poured into a test tube, and again injected into the flame burner. First, the flame becomes luminous (carbon burns), then intensive green staining appears. 2CU + O 2 → 2CUO
2ch - Cl 3 + 5Cuo → CUCL 2 + 4CUCL + 2CO 2 + H 2 O
Check experience should be done using a substance that does not contain halogen (benzene, water, alcohol) instead of chloroform. For cleaning the wire is wetted with chloride acid and calcinate.
II.Opening of functional groups. Based on preliminary analysis (physical properties, elemental analysis), it is estimated to specify the class to which this studied substance belongs. These assumptions confirm with qualitative reactions to functional groups.
1. High-quality reactions to multiple carbon - carbon bonds.a) joining bromine. Hydrocarbons containing double and triple bonds easily attach bromine:
To a solution of 0.1 g (or 0.1 ml) of a substance in 2 - s ml of carbon four chloride or chloroforms is added dropwise when shaking a 5-percent solution of bromine in the same solvent. Instant disappearance of bromine painting indicates the presence of a multiple communication in the substance. But the bromine solution is also discolored by compounds containing movable hydrogen (phenols, aromatic amines, tertiary hydrocarbons). However, the reaction is replaced with the release of hydrogen bromide, the presence of which is easy to detect with a blue lacmus wet paper or Congo. b) Sample with potassium permanganate. In a low-alkaline medium, under the action of potassium permanganate, there is an oxidation of a substance with a discontinuity of a multiple communication, the solution is discolored, and a cade-shaped sediment MNO 2 is formed. - Mangan (I) Oxide. To 0.1 g (or 0.1 ml) of a substance dissolved in water or acetone, added dropwise when shaking a 1 percent solution of potassium permanganate. The rapid disappearance of the raspberry-purple color occurs, and the MNO 2 brown sediment appears. However, Potassium Permanganate oxidizes the substances of other classes: aldehydes, polyhydric alcohols, aromatic amines. At the same time, solutions are also discolored, but oxidation proceeds mostly much more slowly.
2. Detection of aromatic systems.Aromatic compounds, in contrast to aliphatic compounds, are able to easily enter into reactions of substitution, often forming painted compounds. Usually for this use the reaction of nitration and alkylation. Nuting aromatic compounds. ('Caution! Tract!,)Nutration is carried out by nitric acid or a nitrifying mixture:
R - H + HNO 3 → RNO 2 + H 2 O
0.1 g (or 0.1 ml) of the substance is placed in the tube and with continuous shaking, it is gradually added to a ml of a nitrate mixture (1 part of concentrated nitrate acid and 1 part of concentrated sulfate acid). The tube is closed with a plug with a long glass tube, which serves as a reflux, and heated in a water bath. 5 min at 50 0 s. The mixture is poured into a glass with 10 g of chopped ice. If the solid product or oil, insoluble in water falls and differ from the source substance, then the presence of an aromatic system can be assumed. 3. High-quality alcohol reactions.When analyzing alcohols, reactions of substitution as movable hydrogen in the hydroxyl group and the entire hydroxyl group are used. a) Reaction with metallic sodium. Alcohols easily react with sodium, forming alcoholates soluble in alcohol:
2 R - OH + 2 Na → 2 Rona + H 2
A 0.2 - 0.3 ml of anhydrous studied substance is placed in the test tube and a small piece of metal sodium sodium with a wigkey grain is added carefully. The separation of gas in sodium dissolution indicates the presence of active hydrogen. (However, this reaction may also give acids and CH acids.) B) reaction with dumplings (II) hydroxide. In two-, three- and polyhydric alcohols, in contrast to monatomic alcohols, freshly prepared by the dumplings (II) hydroxide dissolves with the formation of a dark-blue solution of complex salts of appropriate derivatives (glycelates, glycerats). A few drops poured into the tube (0.3 - 0.5 ml) 3 percent solution to dumplings (ιι) sulfate, and then 1 ml of 10% sodium hydroxide solution. Shawn the blue precipitate dashes the dumplings (ιι) hydroxide. The dissolution of the precipitate when adding 0.1 g of the studied substance and a change in the color of the solution to dark blue confirm the presence of a polyhydric alcohol with hydroxyl groups located in neighboring carbon atoms.
4. Qualitative reactions of phenols.a) Reaction with Ferum (III) chloride. Phenols are given with fierum (III) chloride intensively painted complex salts. Usually deep blue or purple color appears. Some phenols give green or red staining, it is brighter manifested in water and chloroform and worse in alcohol. Several crystals (or 1 - 2 drops) of the studied substance in 2 ml of water or chloroform are placed in the tube, are then added when shaking 1 to 2 drops 3 percentage solution of ferum (III) chloride. Intense violet or blue color appears in the presence of phenol. Aliphatic phenols with Ferum (ιιι) chloride in alcohol give a brighter color than in water, and for phenols, bloody-red staining is characteristic. b) Reaction with bromine water. Phenols with free ortho-and couple-The items in the benzene core are easily discolored by bromine water, and a precipitate of 2,4,6-tribromophenol is obtained. 
A small amount of studied substance shakes with 1 ml of water, then add bromine water drops. There is a decolorization of the solution andwhite sediment.
5. Quality reactions of aldehydes.Unlike ketones, all aldehydes are easily oxidized. On this property, the discovery of aldehydes is based, but not ketones. a) the reaction of the silver mirror. All aldehydes easily restore the ammonia solution of Argentum (ι) oxide. Ketones do not give this reaction:
In a well-washed tube, 1 ml of silver nitrate solution with 1 ml of diluted sodium hydroxide solution is mixed. The precipitate of the Argentum (ι) of the hydroxide is dissolved when adding a 25% ammonia solution. Several droplets of the alcohol solution of the analyte of the substance are added to the resulting solution. The test tube is placed on water bath And it is heated to 50 0 - 60 0 C. If a brilliant metal silver flare is distinguished on the walls of the tube, this indicates the presence of an aldehyde group in the sample. It should be noted that other easily oxidizing, connections can also be given to this reaction: polyatomic phenols, diketones, some aromatic amines. b) Reaction with Feling Liquid. The aldehydes of the fatty series are able to restore a bivalent downtown to monovalent:
The test tube with 0.05 g of substance and s ml of Feling fluid heated from 5 minutes on a boiling water bath. The appearance of yellow or red sediment Kurubum (i) oxide confirms the presence of aldehyde group. b. Qualitative acid reactions.a) determining acidity. Water-alcohol solutions of carboxylic acids show the acid reaction to the Lacmus, the Congo or the universal indicator. A drop of a water-alcohol solution of the studied substance is applied to the blue wet paper of the Lacmus, the Congo or the universal indicator. In the presence of acid, the indicator changes its color: Lacmus becomes pink, Congo blue, and a universal indicator depending on the acidity - from yellow to orange. It should be borne in mind that of chalfocoslotes, nitrophenols and
some other compounds with a movable "acid" hydrogen that do not contain a carboxyl group can also give a change in the color of the indicator. b) reaction with sodium hydrocarbonate. In the interaction of carboxylic acids with sodium hydrocarbonate, carbon (IY) oxide is selected: 1- 1.5 ml of saturated sodium hydrocarbonate sodium solution is poured into the tube and 0.1 to 0.2 ml of a water-alcohol solution of the test substance is added. Selection of bubbles Carbon (IY) oxide indicates the presence of an acid.
RCOOH + NaHCO 3 → RCOONA + CO 2 + H 2 O
7. Quality amine reactions.Amines dissolve in acids. Many amines (especially aliphatic series) have a characteristic smell (herring, ammonia, etc.). The basicity of amines.Aliphatic amines as strong bases are able to change the color of such indicators as a red lactium, phenolphthalene, universal indicator paper. A drop of aqueous solution of the studied substance is applied to an indicator paper (Lacmus, phenolphthalein, universal indicator paper). Changing the color of the indicator indicates the presence of amines. Depending on the structure of the amine, it changes in a large range. Therefore, it is better to use universal indicator paper. eight. Qualitative reactions of polyfunctional compounds.For high-quality detection of bifunctional compounds (carbohydrates, amino acids), use the complex of the above reactions.
In 1670, English Botanist and Zolog John Rei (1627-1705) held an unusual experiment. He placed in the Vessel of red forest ants, poured water, heated her to a boil and missed a jet of hot steam through a vessel. Such a process of chemists is called distillation with steam and widely used to highlight and clean many organic compounds. After condensation, the Rei Ray received an aqueous solution of a new chemical compound. It showed, therefore, it was called formic acid (modern name - methane). The names of salts and ethers of methane acid - formates are also associated with ants (Lat. Formica - "ant").
Subsequently, entomologists - insect specialists (from Greek. "Enconon" - "Insect" and "Logos" - "Teaching", "Word") determined that females and workers ants in abdomen there are poisonous glands that produce acid. The forest ant is about 5 mg. Acid serves as an insect weapon for sewn and attack. It is unlikely that there is a person who has not experienced their bites. The feeling is very reminiscent of a nettle burn, because formic acid is also contained in the finest hairs of this plant. Fur in the skin, they are rolled, and their contents painfully burn.
Formic acid is also in bee poison, pine needles, silkworm caterpillars, in small quantities it is found in various fruits, in organs, fabrics, excretions of animals and humans. In the XIX century The formic acid (in the form of sodium salt) was made artificially the action of carbon oxide (II) to a wet at elevated temperature: NaOH + CO \u003d HCoona. Conversely, under the action of concentrated formic acid disintegrates with gas release: Nson \u003d CO + H 2 O. This reaction is used in the laboratory to obtain clean. With a strong heating of the sodium salt of formic acid - sodium formate - there is a completely different reaction: carbon atoms of two acid molecules as it were crosslinking and sodium oxalate is formed - oxalic acid salt: 2hCoona \u003d Naooc-Coona + H 2.
The important difference between the formic acid from others is that it, like a double-mounted Yanus, has both properties and acids, and: in its molecule with one "side" can be seen acid (carboxyl) group -o-it, and on the other - the same Carbon atom, which is part of the Aldehyde group of the N-SO- Therefore, formic acid restores silver from its solutions - gives the "silver mirror" reaction, which is characteristic of aldehydes, but not peculiar to acids. In the case of formic acid, this reaction, which is also unusual, is accompanied by the separation of carbon dioxide as a result of oxidation of organic acid (forming) to inorganic (coal), which is unstable and disintegrate: NSon + [o] \u003d but-co-it \u003d CO 2 + N 2 O.
Formic acid is the simplest and at the same time a strong carboxylic acid, it is ten times stronger than acetic. When the German chemist Yustus Libich first received anhydrous formic acid, it turned out that this is a very dangerous compound. If it gets into the skin, it not only burns, but literally dissolves it, leaving hard wounds. As the employee of Libiha Karl Fogt recalled (1817-1895), he had a scar on his hand for his whole life - the result of the "experiment", conducted together with Libich. And not surprisingly, it was subsequently discovered that anhydrous formic acid dissolves even a popron, nylon and other polymers that do not take dilute solutions of other acids and alkalis.
The unexpected use of formic acid has found in the manufacture of so-called heavy liquids - aqueous solutions in which even stones do not sneak. Such liquids are needed by geologists for separating minerals by density. Dissolving the metallic in a 90 percent solution of formic acid, the formate of the NSotl thallium is obtained. This salt in a solid state may not be a density record holder, but it is distinguished by extremely high solubility: in 100 g of water at room temperature, 0.5 kg (!) Toollium formate can be dissolved. In a saturated aqueous solution, the density varies from 3.40 g / cm 3 (at 20 ° C) to 4.76 g / cm 3 (at 90 o C). An even greater density in a solution of a mixture of Thallium formate and malonate Tallulia - Malonic acid salts CH 2 (COOTL) 2.
When dissolving these (in proportions 1: 1 by weight), a liquid with a unique density is formed in a minimum amount of water: 4,324 g / cm 3 at 20 ° C, and at 95 o with the density of the solution, it is possible to bring to 5.0 g / cm 3 . Barite (heavy swarp), quartz, corundum, malachite and even granite float in this solution.
Formic acid has strong bactericidal properties. Therefore, its aqueous solutions are used as a food preservative, and pairs disinfect the container for food products (including wine barrels), destroy bee ticks. A weak aqueous alcoholic solution of formic acid (formic alcohol) is used in medicine for rubbing.
Formic acid or methanaThis is a natural chemical that can be synthesized in laboratories. In nature, it is most often found in the uncens of insects, namely ants and bees.
It is this connection that causes irritation that occurs immediately after the bite is widely used by people. Although it can be sufficiently dangerous at high concentration, but the substance is often used in food products as a preservative or on sowing as a pesticide.
In its pure form, it practically does not have any color and strong smell.
Scientists have added about the ants to the word worker one more lesson in this list: chemist. They noticed that wood ants protect their colonies from the disease by a powerful antibiotic made of wood resin and poison from their body. This is an example of animal pharmacology, as some living beings avoid epidemics.
Like people, forest ants live dense groups, with colonies, hundreds of thousands. This has a dissemination of diseases, especially because their nests are warm, wet and full of dead insects to be used as food by bacteria. Most of the types of ants managed to avoid epidemics, liftingly causing each other and cleaning their colonies. Forest ants take precautions by making antimicrobial resin for their nests. Scientists suspected that there may be an even more difficult secret to preserve health. This secret was the compound: formic acid: a caustic substance produced by ants to fight threats, subjugatory to the victim and cleaning their offspring.
Many animals are protected by substances, but formic acid has a unique "synergistic effect".
This substance is the result of long-term evolutionary development with causative agents of diseases within 50 million years and, possibly, more. It . Therefore, formic acid Application has found wide.
The use of formic acid
For industrial use
One of the most common types of industrial use of formic acid or methane has become the production of leather. Because the substance is so acidic to be an ideal chemical for use when processing the skin. Although the substance is most often used in leather manufacturing, formile acid is used in the process of dyeing and finishing textile products. It is also used as a coagulant in rubber production processes.
In addition to its use in the leather, textile and rubber industries, formic acid derivatives were recently designed to help fight overalls in such rich countries as Austria and Switzerland. These countries use formates that are salts derived from formic acid. These compositions are more efficient than traditional salt and are more environmentally friendly.
With proper use, formates better increase the coupling abilities on slippery surfaces, and also contribute to the change in surfaces of various equipment for many technologies.
Agricultural use
Agriculture accounts for a very high percentage of anti-forming or methane acid throughout the world. Due to its natural antibacterial properties, the substance has reached high use as antibacterial preservatives and pesticides. In this industry, it is most often used as a food additive and is often an ingredient in feed and silo. When the silage is used, the substance performs a double function. In addition to providing a certain level of antibacterial support, it actually allows the silo to start fermentation at a lower temperature, which significantly reduces the total time required to increase food value finished product.
In addition, it is a food additive E236 used in products for people.
Medical application
The use in medicine is extensive, since the substance slows down the processes of rotting, working as a preservative. All sorts of medical solutions with the use of methanol belong to the clinical and pharmacological group of drugs with analgesic properties as an painful and disinfecting agent.
Precautions
Depending on how much the substance is concentrated, it can be imperceptible or on the contrary dangerous. In the course of typical interaction with this chemical, people are interacted only in very low concentrations. When exposed to high concentrations, there are many dangerous side Effectswhich may arise. The most dangerous aspect of formic acid is its high corrosion nature in concentrated form. A highly concentrated amount of formic acid can lead to serious injury, if inhaling it, swallow or touch directly. In this case, ulcers, nausea, burns, blisters and strong discomfort around the affected area are arising. This chemical is located in a sprayed poison of some types of ants and secretion, some types of nettle.
However, at low concentrations, this is useful and used in cosmetology. Cosmetics based on matter give good results as.
Building, Properties and Formulas
Formula formic acid
Formula formula - is the simple member of the carboxylic acid family And also known as methane. Molecular formula - Nson. Molecules consist of a carboxyl group (coxy) with an attached hydrogen atom. In the carboxyl group, carbon atom has a double bond to attach it to an oxygen atom and a single bond connecting it with hydroxyl (OH) of the group.
The substance can be synthetic in laboratories and is successfully engaged. In nature, usually exists in the form of a colorless liquid. This chemical freezes at + 8.3 degrees Celsius and boils 100.7 degrees Celsius. It has an unpleasant smell and is often described as a "sharp" smell.
Because of the universal role in our life and in nature, formic acid is a very interesting substance. In addition to its practical application in agriculture, industry and in the protective mechanisms of insects, it also leads to some very interesting effects and interactions.
Among them is its role in digestive system Muravda. In contrast to most mammals, the anthrade stomach does not contain hydrochloric acid, the main chemical used for digesting in the body of other animals. Due to the high concentration of ants in its nutrition, the game produces digestive juices from the ants, which he eats.
The human body also synthesizes a small amount of methane formic acid from methanol, which we swallow, inhale. A certain amount of methanol in the body comes with aspartame. Aspartame is a dietary supplement E951, a sugar substitute disintegrating in the organism on amino acids: asparty, phenylalanine and methanol. However, these chemicals in our body are usually too diluted to be dangerous.
Although it can be very dangerous in unnaturally high concentrations, but formic acid is actually a universal and extremely useful food additive in industrial chemistry. When consumed at a normal level, very quickly and easily absorbed by our organisms.
Nevertheless, it was found that consumption in highly concentrated amounts of formic acid can lead to damage to the internal organs.
