DEFINITION
Glycerol It is a colorless, viscous, syrupy liquid with a sweet taste. Not poisonous. Glycerin is odorless.
Its melting and boiling points are 18 o C and 290 o C, respectively. Glycerin is hygroscopic and mixes well with water and ethanol. Absolutely pure anhydrous glycerin hardens at +18 o C, but it is extremely difficult to obtain it in solid form. The structure of the glycerol molecule is shown in Fig. 1.
Rice. 1. The structure of the glycerol molecule.
Glycerol is widely distributed in living nature. It plays an important role in metabolic processes in animal organisms, is part of most lipids - fats and other substances contained in animal and plant tissues and performing essential functions in living organisms.
Obtaining glycerol
The oldest method of producing glycerin is the hydrolysis of fats and oils:
Currently, glycerin is produced synthetically from propylene, which is formed during the cracking of petroleum. In this case, different ways of converting propylene into glycerol are used. The most promising method is the oxidation of propylene with atmospheric oxygen in the presence of a catalyst and at high temperature(kat = Cu, t 0 = 370). The process takes place in several stages.
Chemical properties of glycerin
Glycerol is a representative of trihydric alcohols, which, as hydroxyl-containing compounds, are characterized by the same reactions as monohydric alcohols.
Glycerol reacts with active metals (potassium, sodium, etc.), replacing hydrogen in all hydroxyl groups, reacting with hydrogen halides (HCl, HBr, etc.), in dehydration reactions, forming various esters.
Glycerin has specific properties, distinguishing it from monohydric alcohols: it reacts not only with alkali metals, but also with some bases, including insoluble ones, for example with copper (II) hydroxide:
The result of the reaction of glycerol with copper (II) hydroxide is copper glycerate (complex complex compound bright blue). This reaction is a qualitative reaction to polyhydric alcohols.
The most important in practical terms is the nitration reaction of glycerol, which results in the formation of trinitroglycerol C 3 H 5 (ONO 2) 3:
Application of glycerin
Glycerin is a component of many foods, creams and cosmetics.
Examples of problem solving
EXAMPLE 1
Place 2 drops of copper sulfate solution and 2 drops of sodium hydroxide solution into a test tube and mix - a blue gelatinous precipitate of copper (II) hydroxide is formed. Add 1 drop of glycerin to the test tube and shake the contents. The precipitate dissolves and a dark blue color appears due to the formation of copper glycerate.
Process chemistry:
Copper glycerate
Glycerin is a trihydric alcohol. Its acidity is greater than that of monohydric alcohols: an increase in the number of hydroxyl groups enhances the acidic character.
Glycerol easily forms glycerates with heavy metal hydroxides. However, its ability to form metal derivatives (glycerates) with multivalent metals is explained not so much by its increased acidity, but by the fact that this produces intra-complex compounds that are particularly stable. Compounds of this kind are called chelates (from the Greek “hela” - claw).
The reaction with copper hydroxide is a qualitative reaction to polyhydric alcohols and makes it possible to distinguish them from monohydric ones.
Oxidation of ethyl alcohol with copper oxide
Place 2 drops of ethyl alcohol into a dry test tube. Holding a copper wire spiral with tweezers, heat it in the flame of an alcohol lamp until a black coating of copper oxide appears. The still hot spiral is lowered into a test tube with ethyl alcohol. The black surface of the spiral immediately turns golden due to the reduction of copper oxide. In this case, the characteristic smell of acetaldehyde (the smell of apples) is felt.
The formation of acetaldehyde can be detected using a color reaction with fuchsulfurous acid. To do this, place 3 drops of fuchsinous acid solution in a test tube and add 1 drop of the resulting solution with a pipette. A pink-violet color appears. Write the equation for the oxidation reaction of alcohol.
Oxidation of alcohols with a chromium mixture
Place 2 drops of ethyl alcohol in a dry test tube, add 1 drop of sulfuric acid solution and 2 drops of potassium dichromate solution. The orange solution is heated over the flame of an alcohol lamp until the color begins to change to bluish-green. At the same time, the characteristic smell of acetaldehyde is felt.
Carry out a similar reaction using isoamyl alcohol or another alcohol available, noting the smell of the aldehyde formed.
Explain the chemistry of the process the chemistry of the process by writing the equations of the corresponding reactions .
Oxidation of ethyl alcohol with a solution of potassium permanganate
Place 2 drops of ethyl alcohol, 2 drops of potassium permanganate solution and 3 drops of sulfuric acid solution into a dry test tube. Carefully heat the contents of the test tube over the burner flame. The pink solution becomes discolored. There is a characteristic odor of acetaldehyde, which can also be detected by a color reaction with fuchsinsulfurous acid.
Chemistry of the process : (write the reaction equation).
Alcohols oxidize more easily than the corresponding saturated hydrocarbons, which is explained by the influence of the hydroxy group present in their molecule. Primary alcohols are converted during oxidation into aldehydes under mild conditions, and into acids under more severe conditions. Secondary alcohols produce ketones upon oxidation.
When conducting the experiment we use Microlaboratory for chemical experiment
Purpose of the experience: study the qualitative reaction to glycerol.
Equipment: test tubes (2 pcs.).
Reagents: sodium hydroxide solution NaOH, copper(II) sulfate solution CuSO4, glycerol C3H5(OH)3.
1. Add 20-25 drops of copper(II) sulfate into two test tubes.
2. Add excess sodium hydroxide to it.
3. A blue precipitate of copper(II) hydroxide is formed.
4. Add glycerin drop by drop to one test tube.
5. Shake the test tube until the precipitate disappears and a dark blue solution of copper(II) glycerate forms.
6. Compare the color of the solution with the color of copper(II) hydroxide in the control tube.
Conclusion:
A qualitative reaction to glycerin is its interaction with copper (II) hydroxide.
An alcohol that bears little resemblance to alcohol.
Nitroglycerine obtained by nitrating, treating with a mixture of concentrated acids (nitric and sulfuric, the latter is needed to bind the resulting water) of the simplest and most famous of trihydric alcohols - glycerol C3H5 (OH) 3. The production of explosives and gunpowder is one of the main consumers of glycerin, although, of course , is far from the only one.
Nowadays, quite a lot of glycerin is used for the production of polymer materials. Glypthal resins - products of the reaction of glycerin with phthalic acid, when dissolved in alcohol, turn into a good, although somewhat fragile, electrical insulating varnish. Glycerin is also needed for the production of much more popular epoxy resins. Epichlorohydrin is obtained from glycerin - a substance indispensable in the synthesis of the famous “epoxy”. But it is not because of these resins, and especially not because of nitroglycerin, that glycerin is considered a vital substance for us.
It is sold in pharmacies. But in medical practice, pure glycerin is used very limitedly. It softens the skin well. In this capacity - as a skin softener - we mainly use it at home, in everyday life. He plays the same role in the shoe and leather industries. Sometimes glycerin is added to the composition of medical suppositories (with the appropriate dosage, it acts as a laxative). This, in fact, limits the medicinal functions of glycerin. Glycerol derivatives, primarily nitroglycerin and glycerophosphates, are used much more widely in medical practice.
Glycerophosphate, which is sold in pharmacies, actually contains two glycerophosphates. The composition of this medicine, which is prescribed to adults for general fatigue and exhaustion nervous system, and for children with rickets, include 10% calcium glycerophosphate, 2% sodium glycerophosphate and 88% ordinary sugar.
Synthetically obtained from glycerol essential amino acid methionine In medical practice, methionine is used for liver diseases and atherosclerosis.
Glycerol derivatives are always present in the organisms of higher animals and humans. These are fats - esters glycerin and organic acids (palmitic, stearic and oleic) are the most energy-intensive (although not always useful) substances in the body. It is estimated that the energy value of fats is more than two times greater than carbohydrates. It is no coincidence that the body stores this very high-calorie “fuel” in reserve. In addition, the fat layer also serves as thermal insulation: the thermal conductivity of fats is extremely low. In plants, fats are contained mainly in the seeds. This is one of the manifestations of the eternal wisdom of nature: thereby she took care of the energy supply of the next generations...
For the first time on our planet, glycerin was obtained in 1779. Karl Wilhelm Scheele (1742-1786) boiled olive oil with lead litharge (lead oxide) and obtained a sweetish syrupy liquid. He called it sweet butter or the sweet beginning of fats. Scheele, of course, could not determine the exact composition and structure of this “beginning”: organic chemistry was just beginning to develop. The composition of glycerin was discovered in 1823 by the French chemist Michel Eugene Chevreul, who was studying animal fats. And the fact that glycerin is a trihydric alcohol was first established by the famous French chemist Charles Adolphe Wurtz. By the way, he was the first to synthesize the simplest dihydric alcohol, ethylene glycol, in 1857.
Synthetic glycerin from petroleum (more precisely, from propylene) was first obtained in 1938.
Glycerin is partly similar to perhaps the most popular of alcohols - wine, or ethyl. Like wine spirit: It burns with a blue, dim flame. Like wine alcohol, it actively absorbs moisture from the air. As with the formation of alcohol-water solutions, when glycerin and water are mixed, the total volume turns out to be less than the volume of the original components. Like ethyl alcohol, glycerin is needed for the production of gunpowder. But if in this production the role of C2H5OH is, in general, auxiliary, then glycerin is an indispensable raw material for the production of nitroglycerin. This means ballistic gunpowder and dynamite too. Finally, like wine alcohol, glycerin is part of alcoholic beverages.
True, contrary to popular belief, liqueurs do not contain glycerin. Liqueurs are thickened with sugar syrup. But in natural wines, glycerin is necessarily present. Such wines are served in expensive establishments like http://www.tatarcha.net/ and who would have thought that they once wanted to obtain glycerin from them, which is now so cheap.
Glycerol is formed during the hydrolysis of fats when high blood pressure(25,105 pascals) and a temperature slightly above 200 ° C, water destroys fats. But only a few know that the same glycerin is a normal product of the fermentation of sugars. About three percent of the sugar contained in grapes ultimately turns into glycerin. In wine, however, there is much less glycerol: during the ripening process of wine, it is partially converted into other organic matter, but fractions of a percent of glycerin are present in all natural wines, and in some wines it was and is introduced deliberately, for example, when preparing good port wine using classical technology.
At the end of the last century, when the demand for glycerin grew in all industrialized countries, chemists quite seriously discussed the possibility of extracting glycerin from distillery waste, specifically from stillage. Nowadays, the need for glycerin is even greater: but it is still not extracted from stillage. Now glycerin is produced mainly synthetically - from propylene, although the classical method of producing glycerin - by hydrolysis of fats - has not lost its importance.
If pure glycerin is cooled very slowly, it solidifies at about 18 °C. But it is much easier to supercool this peculiar liquid than to turn it into crystals. It can remain liquid even at temperatures below 0°C. Its aqueous solutions behave in a similar way. For example, a solution in which two parts by weight of glycerin are one part of water freezes at minus 46.5 °C.
In addition, glycerin is a moderately viscous liquid, almost non-toxic, well dissolving many organic and inorganic substances. Because of this complex of properties, glycerin has recently found some unexpected uses.
Here we allow ourselves a small lyrical digression.
Mayakovsky in the final part of the poem “About This” has the following lines:
Here he is
big-browed
quiet chemist,
I wrinkled my forehead before the experiment.
Book - “The Whole Earth” -
looking for a name.
Twentieth century.
Resurrect who?
Let's interrupt the quote and turn to the sad prose.
In 1967, the famous American psychologist Professor James Bedford died of leukemia. According to the will of the deceased, immediately upon the onset of clinical death his body was frozen. Bedford hoped that ultra-low temperatures would stop the process of cell decay and keep them unchanged until science found ways to combat the still incurable disease. Then the body will be unfrozen and they will try to bring the scientist back to life...
It is unlikely that these hopes can be considered justified. The leading specialist in the field of resuscitation, Academician of the Academy of Medical Sciences V. A. Negovsky, wrote that by cooling the body to a temperature below + 10 ° C, it is possible to extend the reversible state of clinical death to 40-60 minutes. The use of sub-zero temperatures when freezing living tissues and cells leads to their death.
Nevertheless, hopes of a future resurrection attract many. These hopes are fueled by faith in the omnipotence of future science. To some extent, this belief is supported by certain properties of glycerin and blood substitutes prepared on its basis.
Qualitative reaction to glycerin
In the United States, more than a thousand people were subjected to the freezing procedure in the hope of revival and cure in the future. In the town of Farmingdale in 1971, a “clinic for the dead” began operating. Immediately after death, all the blood is drained from the patient’s body at this clinic and the veins are filled with a special glycerin solution. After this, the body is wrapped in staniol and placed in a vessel with dry ice (-79 ° C), and then in a special sealed capsule with liquid nitrogen. “If you change nitrogen in a timely manner, the body will never decompose,” said the head of the clinic, K. Henderson.
But this is not enough! It was not then that people agreed to posthumous freezing so that their corpses would be well preserved.
Glycerin actually makes it difficult for ice crystals to form, which can damage blood vessels and cells. Once it was already possible to revive the heart of a chicken embryo, cooled in glycerin almost until absolute zero. But they haven’t even tried to do anything like this with a whole organism yet. It is also possible to bring a person out of a state of clinical death years after its onset. Therefore, let us quote Vladimir Aleksandrovich Negovsky once again:
“I know,” he said, “only one such case with a happy ending is the case of the sleeping beauty. A kiss woke her from a hundred-year-old sleep. This is also a method of resuscitation, and also a pleasant one.”
But glycerin, let us add, has nothing to do with it.
Trihydric alcohols (glycerol).
Trihydric alcohols contain three hydroxyl groups at different carbon atoms.
The general formula of CnH2n is 1(OH)3.
The first and main representative of trihydric alcohols is glycerol (propanetriol-1,2,3) HOCH2-CHOH-CH2OH.
Nomenclature. To name trihydric alcohols by systematic nomenclature it is necessary to add the suffix -triol to the name of the corresponding alkane.
The isomerism of trihydric alcohols, like dihydric ones, is determined by the structure carbon chain and the position of three hydroxyl groups in it.
Receipt. 1. Glycerin can be obtained by hydrolysis (saponification) of vegetable or animal fats (in the presence of alkalis or acids):
H2C-O-C//-C17H35 H2C-OH
HC-O-C//-C17H35 + 3H2O ® HC-OH + 3C17H35COOH
H2C-O-C//-C17H35 H2C-OH
triglyceride (fat) glycerin stearic
Hydrolysis in the presence of alkalis leads to the formation of sodium or potassium salts of higher acids - soap (therefore this process is called saponification).
2. Synthesis from propylene (industrial method):
| Cl2, 450-500 oC | H2O (hydrolysis)
CH ----® CH ----®
propylene chloride
CH2OH HOCl (hypo- CH2OH CH2OH
| chlorination) | H2O (hydrolysis) |
®CH ----® CHOH ----® CHOH
|| -HCl | -HCl |
Allyl monochloro-glycerol
alcohol hydrin
glycerin
Chemical properties. The chemical properties of glycerin are very similar to ethylene glycol. It can react with one, two or three hydroxyl groups.
1. Formation of glycerates.
Glycerol, reacting with alkali metals, as well as with heavy metal hydroxides, forms glycerates:
H2С-OH H2C-Oæ /O- CH2
2 HC-OH + Cu(OH)2 ® HC-O/ãO- CH + 2H2O
H2C-OH H2C-OH HO-CH2
copper glycerate
2. Formation of esters. Glycerin forms esters with organic and mineral acids:
H2C-OH HO-NO2 H2C-O-NO2
HC-OH + HO-NO2 -® HC-O-NO2 + 3H2O
H2C-OH HO-NO2 H2C-O-NO2
glycerol nitric trinitrate
glycerol acid
(nitroglycerine)
H2C-OH HO-OC-CH3 H2C-O-COCH3
HC-OH + HO-OC-CH3 -® HC-O-COCH3 + 3H2O
H2C-OH HO-OC-CH3 H2C-O-COCH3
glycerin acetic triacetate
glycerol acid
3. Replacement of hydroxyl groups with halogens. When glycerol reacts with hydrogen halides (HC1, HBr), mono- and dichloro- or bromohydrins are formed:
H2C-OH ® HC-OH ® HC-Cl ù CH2\
| HCl | | HCl | | | KOH | O
HC-OH --| H2C-OH -- | H2C-OH|---® CH/
| -H2O | -H2O | | -KCl, -H2O |
H2C-OH ® H2C-OH ® H2C-Cl û CH2Cl
monochlor-dichlor-epichlor-
hydrins hydrins hydrin
4. Oxidation. The oxidation of glycerol produces various products, the composition of which depends on the nature of the oxidizing agent. The initial oxidation products are: glyceraldehyde HOCH2-CHOH-CHO, dihydroxyacetone HOCH2-CO-CH2OH and the final product (without breaking the carbon chain) - oxalic acid HOOC-COOH.
Individual representatives. Glycerin (propanetriol-1,2,3) HOCH2-CHON-CH2OH - viscous hygroscopic non-toxic liquid (boiling point 290 °C decomposed), sweet in taste. Mixes with water in all proportions. Used for the production of explosives, antifreeze and polyester polymers. Finds application in food (for the production confectionery, liquors, etc.), textile, leather and chemical industry, in perfumery.
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Home / Glycerin
Glycerol
Quality standard
GOST 6824-96
Formula
Description
Viscous liquid, colorless and odorless, sweet in taste. Because of its sweet taste, the substance got its name (Latin> glycos [glycos] - sweet). Mixes with water in any ratio. Not poisonous. The melting point of glycerin is 8°C, the boiling point is 245°C. The density of glycerin is 1.26 g/cm3.
The chemical properties of glycerin are typical of polyhydric alcohols. From organic compounds soluble in alcohol, but insoluble in fats, arenes, ether and chloroform. Glycerin itself dissolves mono- and disaccharides well, as well as inorganic salts and alkalis. Hence the wide range of uses of glycerin. In 1938, a method was developed for the synthesis of glycerol from propylene. A significant portion of glycerol is produced this way.
Application
The scope of glycerin is varied: food industry, tobacco production, medical industry, production of detergents and cosmetics, agriculture, textile, paper and leather industries, plastics production, paint and varnish industry, electrical engineering and radio engineering.
Glycerin is used as a food additive E422 in the production of confectionery products to improve consistency, prevent chocolate from sagging, and increase the volume of bread.
The addition of glycerin reduces the time it takes for bread products to go stale, makes pasta less sticky, and reduces the adhesion of starch during baking.
Glycerin is used in the preparation of extracts of coffee, tea, ginger and other plant substances, which are finely ground and treated with an aqueous solution of glycerin, heated and evaporated. The resulting extract contains about 30% glycerol. Glycerin is widely used in the production of soft drinks. An extract prepared on the basis of glycerin, when diluted, gives drinks “softness”.
Due to its high hygroscopicity, glycerin is used when preparing tobacco (to keep the leaves moist and eliminate the unpleasant taste).
In medicine and in the production of pharmaceuticals, glycerin is used to dissolve drugs, increase the viscosity of liquid preparations, protect against changes during fermentation of liquids, and from drying out ointments, pastes and creams. Using glycerin instead of water, you can prepare highly concentrated medical solutions. It also dissolves iodine, bromine, phenol, thymol, mercuric chloride and alkaloids well. Glycerin has antiseptic properties.
Glycerin enhances the cleaning power of most types of toilet soap in which it is used, gives the skin whiteness and softens it.
IN agriculture glycerin is used to treat seeds, which promotes their good germination, trees and shrubs, which protects the bark from bad weather.
Glycerin in the textile industry is used in weaving, spinning, and dyeing, which gives fabrics softness and elasticity. It is used to produce aniline dyes, paint solvents, and in the production of synthetic silk and wool.
In the paper industry, glycerin is used in the production of tissue paper, parchment, tracing paper, paper napkins and heat-resistant paper.
In the leather industry, glycerin solutions are used in the process of fattening leather, adding it to aqueous solutions of barium chloride. Glycerin is part of wax emulsions for tanning leather.
Glycerin is widely used in the production of transparent packaging materials.
QUALITATIVE REACTION TO GLYCEROL
Due to its plasticity, ability to retain moisture and withstand cold, glycerin is used as a plasticizer in the production of cellophane. Glycerin is an integral part in the production of plastics and resins. Polyglycerols are used to coat paper bags in which oil is stored. Paper packaging material becomes fire-resistant if it is impregnated under pressure with an aqueous solution of glycerin, borax, ammonium phosphate, and gelatin.
In the paint and varnish industry, glycerin is a component of polishing compounds, especially varnishes used for final finishing.
In radio engineering, glycerin is widely used in the production of electrolytic capacitors, alkyd resins, which are used as an insulating material, in the processing of aluminum and its alloys.
Medicinal properties and indications for use of glycerin
Glycerin in a 10-30% mixture with water, ethyl alcohol, lanolin, and petroleum jelly has the ability to soften tissue and is usually used as an emollient for the skin and mucous membranes.
Glycerin is used as a base for ointments and as a solvent for a number of medicinal substances(borax, tannin, ichthyol, etc.).
Other non-fat skin care products are also prepared on the basis of glycerin - creams (glycerolate creams), jellies (fat-free ointments) and other dosage forms and cosmetics, for example, 3-5% glycerin is added to lotions to soften the skin).
In a mixture with ammonia and alcohol (ammonium alcohol - 20.0, glycerin - 40.0, ethyl alcohol 70% - 40.0), glycerin is used as a means to soften the skin of the hands (for wiping hands with dry skin).
Package
From 1 and 2.5 liter polyethylene bottles for research and laboratory applications, 25 and 190 liter plastic drums, up to 1000 liter containers.
Transportation
Transported in aluminum or steel railway tanks and barrels.
Storage
Store glycerin in sealed aluminum or stainless steel containers under a nitrogen blanket.
in a ventilated, dry room at low temperature.
The shelf life of glycerin is 5 years from the date of manufacture.
Specifications
— Molar mass- 92.1 g/mol
— Density - 1.261 g/cm3
— Thermal properties
— Melting point - 18 °C
— Boiling point - 290 °C
— Optical refractive index - 1.4729
CAS number - 56-81-5
— SMILES - OCC(O)CO
| Indicators | Glycerol | |||
| Ts-98 | PK-94 | T-94 | T-88 | |
| Relative density at 20 °C 1 in relation to water of the same temperature, not less | 1,2584 | 1,2481 | 1,2481 | 1,2322 |
| Density at 20 °C, g/cm3, not less | 1,255 | 1,244 | 1,244 | — |
| Reaction of glycerol, 0.1 mol/dm3 solution of HC1 or KOH, cm3, no more | 1,5 | 1,5 | 1,5 | 1,5 |
| Mass fraction of pure glycerin, %, not less | 98 | 94 | 94 | 88 |
| Mass fraction of ash, %, no more | 0,14 | 0,01 | 0,02 | 0,25 |
| Saponification coefficient (esters), mg KOH per 1 g of glycerol, no more | 0,7 | 0,7 | 2,0 | — |
| Chlorides | Traces | Absence | Traces | — |
| Sulfuric acid compounds (sulfites) | « | « | « | — |
| Carbohydrates, acrolein and other reducing substances, iron, arsenic | Absence | |||
| Lead content, mg/kg, no more | — | 5,0 | — | — |
Shipment from 1 kg! Delivery throughout the Russian Federation! We work only with Legal entities (including individual entrepreneurs) and only by bank transfer!
Glycerin or, according to the international nomenclature, propanetriol -1,2,3 is a complex substance that belongs to polyhydric alcohols, or rather, it is a trihydric alcohol, because has 3 hydroxyl groups - OH. The chemical properties of glycerin are similar to those of glycerin, but are more pronounced due to the fact that there are more hydroxyl groups and they influence each other.
Glycerol, like alcohols with one hydroxyl group, is highly soluble in water. This, one might say, is also a qualitative reaction to glycerin, since it dissolves in water in almost any ratio. This property is used in the production of antifreeze - liquids that do not freeze and cool the engines of cars and aircraft.
Glycerin also interacts with potassium permanganate. This is a qualitative reaction to glycerin, which is also called the Scheele volcano. To carry it out, you need to add 1-2 drops of anhydrous glycerin to the potassium permanganate powder, which is poured in the form of a slide with a depression in a porcelain bowl. After a minute, the mixture spontaneously ignites. During the reaction, a large amount of heat is released, and hot particles of reaction products and water vapor fly away. This reaction is redox.
Glycerin is hygroscopic, i.e. able to retain moisture. It is on this property that the following qualitative reaction to glycerin is based. It is carried out in a fume hood. To carry it out, pour approximately 1 cm3 of crystalline potassium hydrogen sulfate (KHSO4) into a clean, dry test tube. Add 1-2 drops of glycerin, then heat until a pungent odor appears. Potassium hydrogen sulfate acts here as a water-absorbing substance, which begins to manifest itself when heated. Glycerin, losing water, is converted into an unsaturated compound - acrolein, which has a sharp, unpleasant odor. C3H5(OH)3 - H2C=CH-CHO + 2 H2O.
The reaction of glycerol with copper hydroxide is qualitative and serves to determine not only glycerol, but also others. In order to carry it out, it is initially necessary to prepare a fresh solution of copper (II) hydroxide. To do this, we add copper (II) hydroxide, which forms a blue precipitate. We add a few drops of glycerin to this test tube with the sediment and notice that the sediment has disappeared and the solution has acquired a blue color.
The resulting complex is called copper alcoholate or glycerate. A qualitative reaction to glycerin with copper (II) hydroxide is used if the glycerin is in pure form or in an aqueous solution. To carry out such reactions in which glycerin is present with impurities, it is necessary to preliminarily purify it from them.
Qualitative reactions for glycerol help to detect it in any environment. It is actively used for the determination of glycerol in food, cosmetics, perfumes, medicines and antifreezes.
