Glycerin or according to the international nomenclature propanetriol -1,2,3 - compound, which refers to polyhydric alcohols, or rather is a trihydric alcohol, because has 3 hydroxyl groups - OH. Chemical properties glycerol are similar to those of glycerol, 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 car and aircraft engines.
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, it releases a large number of heat, 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 to it and obtain copper (II) hydroxide, which forms a precipitate blue color. 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. Qualitative reaction for glycerin with copper (II) hydroxide is used if glycerin is in pure form or in aqueous solution. To carry out such reactions in which glycerin is present with impurities, it is necessary to pre-clean it from them.
Qualitative reactions to glycerol help detect it in any environment. It is actively used for the determination of glycerol in food, cosmetics, perfumes, medicines and antifreezes.
C 3 H B (OH) E (Molecular weight 92.06)
Qualitative reactions
1. When glycerin is heated with double the amount of potassium bisulfate KHS0 4 until slight charring begins, the smell of acrolein is felt, which strongly irritates the mucous membranes and causes lacrimation. A piece of paper moistened with Nessler's reagent turns black when immersed in the vapor of released acrolein (from the released mercury):
2. The Denizhe reaction is based on the oxidation of glycerol bromine water to dioxyacetone:
Heat 0.1 g of sample with 10 ml of freshly prepared bromine water(0.3 ml bromine in 100 ml water) for 20 minutes and then the remaining bromine is removed by boiling. The resulting dihydroxyacetone is reduced by Nessler's reagent and Fehling's solution.
quantitation
1. Refractometric determination. The glycerol content in aqueous solutions that do not contain other substances can be determined refractometrically by the refractive index, using the appropriate table.
2. Acetine method. A sample of glycerol is acetylated to obtain acetic ester glycerol - triacetin. By saponifying triacetin, the amount of alkali consumed is determined and the amount of glycerol is calculated. Due to the fact that the acetylation of glycerol requires special High Quality acetic anhydride, which should contain only traces of free acetic acid, is preferred for the determination of glycerol by the dichromate method.
3. Bichromate method of determination. Purified glycerin, which does not contain foreign oxidizable substances, is oxidized in an acidic environment with dichromate to carbon dioxide and water:
Using an excess of a titrated solution of potassium dichromate, the excess of the latter is determined iodometrically:
The released iodine is titrated with sodium thiosulfate solution. For the definition technique, see Meyer (1937).
4. The method of oxidation with bromine (see above) is more convenient for determining small amounts of glycerol.
A sample of glycerin solution corresponding to 0.02-0.04 g of 100% glycerin is placed in a conical flask with a ground stopper. Acidic solutions are neutralized with 0.1 N. alkali solution in the presence of one drop of methyl orange solution. Then pour in 10 ml of 0.1% bromine water, moisten the stopper with a solution of potassium iodide and leave the reaction mixture alone for 15 minutes. Pour in 10 ml of a 10% solution of potassium iodide, 50-100 ml of water and titrate the iodine with 0.02 N. sodium thiosulfate solution in the presence of starch. At the same time, a blind experiment is performed.
Where A- number of u,uz n. sodium thiosulfate solution in milliliters, used for blind experiment, b- the amount of the same solution in milliliters consumed during the determination, e- weight in milligrams.
The test can not be done completely, but look, if possible, most questions. With uv. I.V.
Methods of knowledge in chemistry. Chemistry and life ( open bank 2014)
Part A
1.What reagent is used to detect chloride ion?
3. Ammonium salts can be detected using a substance whose formula is
5.Aqueous solutions of sulfuric and nitric acids can be distinguished using
7.Formula of the propylene polymerization product
9. A substance that is non-toxic to humans is
11. The process of decomposition of petroleum hydrocarbons into more volatile substances is called
13. The chemical structure of butadiene rubber is expressed by the formula
15. Method of processing oil and petroleum products, in which don't happen
chemical reactions is
16. When an alcohol solution of alkali acts on 2-chlorobutane, it predominantly forms
17. The products of firing pyrite FeS 2 are
19.By displacing water it is forbidden
collect
20.When alkaline hydrolysis 1,2-dichloropropane is formed
21. An aqueous solution of potassium permanganate changes its color under the influence of
The monomer for producing polyethylene is
23. You can detect sulfate ion in a solution using
24.Amino acetic acid can be obtained by reacting ammonia with
25.Environmentally friendly fuel is
35.Iron (III) hydroxide is formed by the action of alkali solutions on
36.Aniline can be distinguished from benzene using
38.Bromoethane it is forbidden
get
interaction
39. When an aqueous solution of alkali acts on monobromoalkanes, they are predominantly formed
40. When a concentrated alcohol solution of alkali acts on monobromoalkanes upon heating, they are predominantly formed
41.Has strong antiseptic properties
42.Acetylene is produced in industry
43.Chloroprene rubber is obtained from
45. In the reaction scheme NaOH + X C 2 H 5 OH + NaCl with the substance “ X" is
46.Ethylene can be obtained by dehydration
The process of aromatizing gasoline is called
48. The presence of Cu 2+ and SO 4 2– ions in a solution can be confirmed using solutions:
50.For industrial production methanol from synthesis gas is not
characteristic
51.What is the reaction not used
in the production of sulfuric acid?
53.What process in the production of sulfuric acid is carried out in a contact apparatus?
54. Alkaline hydrolysis of 2-chlorobutane predominantly produces
55. The reaction for the industrial production of methanol, the scheme of which is CO + H 2 CH 3 OH, is
56.For the production of sulfuric acid raw materials is not
58. The main product of the reaction of chloroethane with an excess of an aqueous solution of potassium hydroxide is
59. Purple coloring appears when exposed to protein
60. A bright blue solution is formed when copper (II) hydroxide reacts with
61. The monomer for the production of polystyrene (– CH 2 – CH(C 6 H 5) –) n is
62. Forms explosive mixtures with air
63. Sodium chloride solution is used to detect ions
65. The monomer for producing artificial rubber according to Lebedev’s method is
66.The monomer for producing polyvinyl chloride is
67. An apparatus for separating liquid production products is
68.Butadiene-1,3 is obtained from
69.Basic natural source butane is
70. A qualitative reaction to formaldehyde is its interaction with
71. Proteins become yellow when exposed to
73. The separation of oil into fractions is carried out in the process
75.Acetic acid it is forbidden
get
76. Propanol-1 is formed as a result of a reaction, the scheme of which
78. Methods for producing alkenes include:
79.Butanol-2 and potassium chloride are formed by interaction
80. The reaction by which sulfate ion can be determined is:
82. A characteristic reaction for polyhydric alcohols is interaction with
84.In a galvanized vessel it is forbidden
store the solution
86.In the production of ammonia, the raw material is
87. Forms an explosive mixture with air
89. To obtain ammonia in industry they use
90. Are the following judgments about the rules for handling substances correct?
A. In the laboratory you cannot get acquainted with the smell of substances.
B. Lead salts are very poisonous.
91.Are the following judgments about the rules for handling substances correct?
A. In the laboratory you can get acquainted with the smell and taste of substances.
B. Chlorine gas is very poisonous.
92.Are the following judgments about industrial methods of producing metals true?
A. Pyrometallurgy is based on the process of recovering metals from ores at high temperatures.
B. In industry, carbon monoxide (II) and coke are used as reducing agents.
93. In the production of sulfuric acid at the stage of SO 2 oxidation to increase product yield
94.Reagent for polyhydric alcohols is
96. Each of two substances enters into the “silver mirror” reaction:
97. Using the “fluidized bed” method in industry,
98.Pentanol-1 is formed as a result of the interaction
99. A natural polymer is
100.Pentanoic acid is formed as a result of the interaction
101.Methane is the main component
103.In one stage, butane can be obtained from
104.Propanic acid is formed as a result of the interaction
105.Are the following judgments about indicators correct?
A. Phenolphthalein changes color in acid solution.
B. Litmus can be used to detect both acids and alkalis.
106. Rubber is formed during polymerization
107.In the laboratory, acetic acid can be obtained by oxidation
108. A qualitative reaction to polyhydric alcohols is the reaction with
109.Main component natural gas is
110. Potassium permanganate solution can be used to detect
111. Reactions of synthesis of high-molecular substances include
112. Sodium acetate, when heated with solid sodium hydroxide, forms
114. Cracking of petroleum products is carried out in order to obtain
115.When heating the limits monohydric alcohols With carboxylic acids in the presence of sulfuric acid are formed
116.When acetaldehyde reacts with hydrogen, it forms
117.The industrial production of methanol is based on chemical reaction, whose equation
119.Are the following judgments about ammonia production correct?
A. In industry, ammonia is obtained by synthesis from simple substances.
B. The reaction of ammonia synthesis is exothermic.
120.Butanoic acid is formed as a result of the interaction
121.Ammonia solution of silver (I) oxide is a reagent for
122.Are the following judgments about oil refining methods true?
A. Secondary oil refining methods include cracking processes: thermal and catalytic.
B. During catalytic cracking, along with splitting reactions, isomerization reactions of saturated hydrocarbons occur.
123. Freshly precipitated copper(II) hydroxide reacts with
124.Propanol-1 is formed as a result of the interaction
125.Which of the following ions is the least toxic?
127. A solution of potassium permanganate is discolored by each of two substances:
128.Butanoic acid can be obtained by reacting
129.Are the following judgments about the rules for handling substances correct?
A. It is prohibited to taste substances in the laboratory.
B. Mercury salts should be handled with extreme caution due to their toxicity.
130.Keep environmentally friendly clean fuel include
131.What alcohols it is forbidden
obtained by hydration of alkenes?
132. To obtain acetylene in the laboratory they use
133.Butanol-1 is formed as a result of the interaction
134.Are the following judgments about the rules for handling substances and equipment correct?
A. Thickened oil paint should not be heated over an open fire.
B. Spent organic matter It is prohibited to pour into a drain.
135.Polypropylene is obtained from propene as a result of the reaction
136. To synthesize butane in the laboratory, metallic sodium and
137. Esters are formed as a result of the reaction
139. The starting material for the production of butadiene rubber is
141.Polymer having the formula
get from
142.Are the following statements about the toxicity of substances and the rules of work in the laboratory correct?
A. The most toxic gases include oxygen and hydrogen.
143. At the last stage of sulfuric acid production, sulfur(VI) oxide is absorbed
144.Are the following judgments about working with gases true?
A. Carbon dioxide can be dried by passing it through concentrated sulfuric acid.
B. To dry hydrogen chloride you can use solid hydroxide calcium.
145.The fluidized bed method in the production of sulfuric acid is used in the process
146. When propylene is hydrated, it is predominantly formed
147.Are the following judgments about safety rules correct?
A. When preparing acid solutions, you should carefully (in a thin stream) pour the acid into cold water, stirring the solution.
B. It is better to dissolve solid alkalis in porcelain rather than in thick-walled glass containers.
148. In the production of sulfuric acid, a catalyst is used at the stage
149.Butanol-2 is formed as a result of the interaction
151.The “fluidized bed” method is used in production
152.Acetylene is produced in the laboratory
153.Each of two substances is non-toxic:
155.Butanol-2 can be obtained by interaction
156.Each of two gases is toxic:
158.Pentanoic acid is formed as a result of the interaction
159. A solution containing ions can serve as a reagent for carbonate ions
161.Butanoic acid is formed as a result of the interaction
162. The qualitative composition of barium chloride can be determined using solutions containing ions
164.A reagent for ammonium cations is a substance whose formula is
166. Phosphate ions in solution can be detected using a substance whose formula is
168. Acetic acid is formed when
170. Are the following judgments true about scientific principles industrial synthesis of ammonia?
A. Ammonia synthesis is carried out based on the circulation principle.
B. In industry, ammonia synthesis is carried out in a “fluidized” bed.
171.Calcium propionate is formed by the interaction
172. Are the following judgments about the production of sulfuric acid in industry correct?
A. Concentrated sulfuric acid is used to absorb sulfur (VI) oxide.
B. Potassium hydroxide is used to dry sulfur(IV) oxide.
Glycerin, penetrating into the leaves, evaporates more slowly than water, changes their color, dries, maintaining their shape and giving the leaves elasticity. The results are beautiful shades from beige to dark brown. Flowers dried in this way can withstand long-term storage.
For this, mixtures of technical glycerin and water are used in a ratio of 1: 2 and 1: 3. For soft-leaved plants, a solution of one part glycerin and two parts water is suitable; for tougher leaves, a more concentrated one is needed. Sometimes the leaves are dried in equal parts glycerin and water.
The range of plants is quite wide. These are barberry, birch, beech, heather, oak, chestnut, clematis, maple, laurel, oleaster, mahonia, magnolia, chokeberry, rhododendron, boxwood, eucalyptus, hops.
Branches with leaves must be cut before August, when the leaves are still young and full of moisture.
The stems are cut obliquely, removing the lower leaves and removing 6 cm of very thick bark; the ends of the stems are split to a length of 10 cm. All this contributes to better absorption of the solution. Branches prepared for drying must be immersed in cold water before being immersed in the solution, trimmed again without removing them from the water, and then lowered into the solution.
Canning technology: glycerin is mixed with boiling water, branches with leaves are removed from cold water, placed in a hot solution to a depth of at least 15 cm. Then the solution is gradually cooled. The place where the vessel with branches and glycerin solution stands should be light so that the process of absorption of glycerin and water occurs better. Sometimes it is placed in a dark place. The stems are kept in the solution until the leaves change color. The time during which the preservation process takes place varies depending on the type of plant and the temperature of the room. Typically this process lasts from several days to 2-3 weeks.
It is very important to remove the leaves the moment they become oily. If you skip this moment, the leaves will be sticky and dust will settle on them.
You can also place cut branches of hawthorn, cotoneaster, ligustrum, juniper, silver poplar, and blackberries in an aqueous solution of glycerin.
Houseplants for drying in a glycerin solution - aralia, aspidistra, camellia bromeliad, ficus. Their leaves are completely immersed in a solution of glycerin and water. To do this you need to have a small vessel. As soon as the leaves begin to change color, they should be removed from the solution, rinsed lightly and quickly dried on blotting paper in a warm place.
Perennials for drying (canning) - gypsophila with flowers, crocosmia, meadowsweet; annuals - molucella with flowers.
The leaves of such plants are dried in a solution of glycerin in water. ornamental plants, like bergenia, gladiolus, iris, peony (June), fern (the solution for them is more concentrated), hosta.
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GLYCEROL, propanetriol (1, 2, 3), α, β, γ-trioxypropane, trihydric alcohol CH 2 OH CH 2 OH. Glycerol is extremely common in nature, where it occurs in the form esters- glycerides. In animal organisms, glycerol is also found in the form of lecithins - esters of glycerophosphoric acid. In addition, glycerin is normal integral part wine, as it is formed during the fermentation of grape sugar.
Pure glycerin is a syrupy, thick liquid with a sweet taste, odorless, neutral reaction, D 4 20 = 1.2604. With prolonged strong cooling, it hardens into crystals of the orthorhombic system, melting at 17-20°. Glycerin is very hygroscopic. It mixes with water and alcohol in all respects and dissolves inorganic salts; insoluble in ether and chloroform. At normal pressure it boils at 290° with slight decomposition, but under reduced pressure and with water steam it distills without decomposition; boiling point at 50 mm 205°, at 0.05 mm 115-116°. Anhydrous glycerin sublimes already at 100-150°.
When heated rapidly, it loses water and produces heavy vapors with the odor of acrolein, burning with a blue flame; upon careful oxidation, glycerol gives an aldehyde - glycerose CH 2 OH·CHOH·SON; upon further oxidation (by the action of HNO 3) it produces acids: glyceric CH 2 OH CHOH COOH, oxalic COOH COOH, glycol CH 2 OH COOH and glyoxylic CH 2 OH COOH. Glycerin reacts easily with inorganic acids; Thus, with phosphoric acid, glycerol forms glycerol phosphorus acid CH 2 OH CH(OH) CH 2 O PO(OH) 2; glycerol heated with borax produces glycerol borate, which is used in medicine as an antiseptic. When exposed to metals, glycerol gives glycerates, b. including crystalline compound. By the action of hydrohalic acids or other halide compounds on glycerol, mono-, di- and trihalohydrins glycerin; By the action of alcohol halohydrins on glycerates, mixed glycerol esters are obtained - liquids resembling the properties of esters of monohydric alcohols. Like glycols, glycerol, losing water, gives an anhydride - glycide
Homologues of glycerol, trihydric alcohols, so-called. glycerols, little studied; some are obtained artificially and are thick, non-crystallizing liquids with a sweet taste, highly soluble in water and alcohol.
Synthetic methods for producing glycerol do not have technical significance. In technology, glycerin is extracted by splitting fats (saponification). The breakdown of fat is the decomposition of glyceride into free fatty acid and glycerol according to the equation:
There are many methods of splitting; the most important are: 1) autoclave method, 2) Twitchell method, 3) Krebitz method and 4) enzymatic. The most widely used method is the Twitchell method, followed by the autoclave method. In the USSR, in addition to the autoclave method, another method is used, which is a slight modification of the Twitchell method - splitting through “contact”.
1. Digestion is carried out in autoclaves in the following way: purified fat with water and 1-2% lime is heated in an autoclave (up to 150-180°), equipped with a tube reaching almost to the bottom (Fig. 1), at 8-12 atm pressure.
With this treatment, fats break down, forming calcium salts of fatty acids (soap) and glycerol in aqueous solution - glycerin water- according to the equation:
The splitting operation lasts 6-8 hours, after which the reaction mixture is cooled somewhat and released from the autoclave. Due to the pressure remaining in the autoclave, the liquid rises through the tube, with glycerin water coming first, which is collected in a separate receiver and left to settle. Settling occurs very slowly, especially if the fat taken for saponification was poorly purified. When impurities float to the surface, they are separated, and the solution is subjected to further processing to separate glycerol from it. IN Lately Instead of lime, they began to use magnesia or superheated steam in the presence of zinc oxide and zinc dust. For 2500 kg of fat, take 15 kg of zinc oxide, 7 kg of zinc dust and 500 liters of water. These changes make it possible to carry out splitting at a lower pressure (6-7 atm) and obtain glycerol with less loss. In Russia before the war of 1914-18. The breakdown of fats was carried out almost exclusively in soap and stearin factories. True, in some places (in Moscow, Lodz, Warsaw) there were fat-splitting plants that produced glycerin for the textile industry, but their output was insignificant. IN Western Europe The fat-breaking business is very widespread: in addition to the production of glycerin at soap and stearin factories as a by-product, there is big number special fat-splitting plants that extract glycerol from fats.
2. The Twitchell method (acid) is a modification of the old method of breaking down fats with sulfuric acid, in which sulfuric acid plays the role of an emulsion former and at the same time enters chemical reaction with glycerides of unsaturated acids and glycerol, giving sulfonic acids, which decompose upon boiling back into sulfuric acid, fatty acids and glycerin. The Twitchell method is based on the emulsifying effect of the reagent he proposed (a mixture of fatty aromatic sulfonic acids) - Twitchell's reagent. In an emulsified state, the fat presents a huge surface area to the splitting action of water, as a result of which the reaction is so accelerated that it becomes possible to carry out the splitting without using an autoclave. The splitter - Petrov’s “contact”, which has now replaced Twitchell’s reagent (and others like it), is a 40% aqueous solution of cyclic sulfonic acids general formula: C n H 2n–9 SO 3 H and C n H 2 n–11 SO 3 H. Work using this method is carried out as follows. sample: the fat is placed in a cauldron equipped with a stirrer, heated to 50° and, with strong shaking, 1.5% sulfuric acid 60° Ве is added to it (to destroy protein and other impurities). Then the mixture is diluted with water (20%), a splitter (0.5-1.25%) is added and boiled. After 24 hours, usually 85% of the fat is broken down. The mass is allowed to settle, the glycerin water is separated and subjected to further processing to isolate glycerol. The autoclave method gives good exits and product quality, but its equipment is expensive. Installing a Twitchell is cheaper, but is more likely to wear out; yields are smaller and the product is of poorer quality.
3. The Krebitz (alkaline) method, used in soap making, is also based on increasing the reacting surface of fat. This is achieved by vigorously stirring the fat with lime milk (0.5-3% alkali is sufficient to break down the fat) while simultaneously passing a jet of steam into the mixture. Then the mixture is left for 12 hours. During this time, saponification ends. The result is lime soap in the form of a porous, brittle mass, and glycerin goes into solution. Since a significant proportion of glycerin is captured by soap, the soap is crushed and washed hot water, and the washing waters are added to the main glycerin solution.
4. Enzymatic breakdown of fats occurs through the use of special (lipolytic) enzymes found in the seeds of some plants, mainly. arr. castor bean (Ricinus communis). For this purpose, to remove oil, crushed castor bean seeds are ground with weak sulfuric acid until an emulsion is formed (inactive parts are separated by centrifugation). This emulsion (“enzyme milk”) is used directly for digestion, which at a temperature of 30-40° ends in 2-3 days: fatty acids are separated, and 40-50% glycerol remains in the solution. The enzymatic method was first blamed big hopes, but in practice many difficulties were encountered, as a result of which, despite the improvements introduced by the work of Wilstatter, Hoyer, Nicloux and others, he did not receive widespread. During the war of 1914-18, due to the need for large quantities of glycerin and the lack of fats, many countries turned attention to the possibility of recycling waste from soap production. Solutions obtained after salting out soap, the so-called. soap liquors containing 5-10% glycerin were simply poured out by many factories; a lot of glycerin also remained in the so-called. adhesive soaps. So. arr. a significant part of the glycerol extracted from fats was lost unproductively. Therefore, in Germany in 1914 there was a ban on the production of adhesive soaps, and large factories began to buy up soap liquors to extract glycerin from them.
Over the past 10 years, much attention has been paid to the method of producing glycerol by fermentation. Pasteur also found that during the alcoholic fermentation of sugar a small amount of glycerol is formed (about 3%). Konnstein and Ludecke increased the yield of glycerol to 36.7% by adding sodium sulfide Na 2 SO 3 to the fermenting mixture. During the war, this method was used in America (Porto Rico) and Western Europe to obtain glycerin from molasses (waste from beet sugar production), and with its help more than 1 million kg of glycerin was produced. In Germany, glycerol obtained by fermentation is called Protol or Fermentol.
Solutions of glycerin obtained in one way or another are highly diluted and contaminated; To extract glycerol from them, they are treated with various chemical reagents (calcium is removed with oxalic acid, magnesium is removed with lime water, zinc - barium carbonate), and then evaporated in open vessels (Fig. 2) or in vacuum devices of various designs.
It is especially difficult to clean and evaporate soap lyes, since they are heavily contaminated with colloidal soap solutions and mineral salts. According to the Domier C° method, 0.5% lime is first added to the solution, and then it is evaporated until the salts begin to crystallize. The alkalis formed in this process lather the resinous substances in the solution, and the soap collects in the form of foam on the surface, carrying with it the remaining impurities. IN the latest ways After neutralization, soap liquors are treated with aluminum or iron sulfate, filtered to separate settled impurities, and the weakly acidic filtrate is neutralized with soda mixed with paper pulp. The latter adsorbs the remaining contaminants, after which the solutions are filtered and evaporated in special vacuum devices equipped with a reservoir for collecting precipitated salts. By evaporating glycerin waters, crude glycerin is obtained, which has dark color and containing a significant amount inorganic salts. This technical glycerin is either directly sold or subjected to further purification. For this purpose, the glycerin solution is passed through a series of filters filled with calcined bone charcoal, so that the glycerin passes first through the used charcoal, and finally through the fresh one (countercurrent principle). The entire battery of filters is heated to 80° by steam passed between the walls of the filter lining. The method gives good results, but its use is limited due to high cost, slow filtration and the need for periodic regeneration of bone char. A simpler method is heating with bleaching powders (charcoal, carborafine, etc.), but it gives worse results.
To obtain pure glycerin, one has to resort to distillation (the method of obtaining pure glycerin by crystallization is currently abandoned in Western Europe as unprofitable). Distillation is carried out in copper or iron boilers using superheated steam and vacuum. This speeds up the process, saves fuel and improves the quality of the resulting products, since lowering the distillation temperature prevents the possibility of glycerin decomposing from overheating, and the glycerin is almost anhydrous. Distillation plants from different companies differ from each other in details, but in general they are designed according to the same principle. According to Ruymbeke and Jollins (Fig. 3), steam, before entering the distillation cube A, passes through a coil (c) located in the heating cube E, into which steam is admitted from the steam boiler through a pipe (f).
Due to the wide diameter of the coil (c), the steam passing through it (from pipe d with a smaller diameter) expands, cooling at the same time, but is immediately heated again to its original temperature by the steam surrounding the coil. The expanded and heated steam enters the distillation cube A, filled to 1/3 of the volume with crude glycerin; through a perforated pipe (b) steam is introduced into the distilled mass; The distillate is condensed in condenser B, from where it passes into vessel C, where it is collected. This technique simultaneously avoids both the cooling of the steam during its expansion in the distillation cube itself, and the decomposition of glycerin from overheating, which took place in previous installations where the steam first passed through a superheater. In fig. Figure 4 shows a modern installation of distillation apparatus from Feld and Forstman.
Crude glycerin is loaded into boiler B so that it fills no more than 1/3 of its volume. Steam is introduced into superheater U to heat the coil, and at the same time into still B to raise the temperature of the glycerin. Then steam is introduced into the coil and, when it expands and heats up, it is passed into the distillation cube. Vigorous distillation begins immediately. Glycerin is carried away with the steam and condenses in the system of refrigerators G, while the steam carries further into a special water refrigerator K and also condenses. The work takes place in a vacuum. From the point of view of fuel economy, the multiplication installation of Marx & Rawolle in New York is interesting, where the same stream of steam is extremely efficiently utilized.
Glycerin is commercially available in various purities. The following varieties are distinguished: 1) double distilled, chemically pure glycerin- Glycerinum purissimum albissimum, 30° or 28° Ве; 2) G. Album - too pure product, but distilled once; 3) dynamite glycerin- distilled and in highest degree pure product; slightly yellow color, 28° Ве; specific gravity 1,261-1,263; 4) refined glycerin- not subjected to distillation, but only clarified, comes in two grades: white and yellow, 28° and 30° Ве; 5) raw, unrefined glycerin (technical): a) from soap liquors and b) saponification(obtained by autoclave).
Glycerin is widely used in many branches of industry and technology. Large quantities Glycerin is used to prepare nitroglycerin and dynamite. Glycerin is used for protection various products from drying out: in soap making, leather tanning, tobacco production, etc. Its preservative properties make it possible to use it in the canning industry and for preserving anatomical and botanical preparations. Glycerin is also used as a lubricant to lubricate various mechanisms: watches, pumps, refrigeration and ice-making machines. It is then used for hydraulic presses and railway brakes. In the textile industry it is used in calico printing for various finishes. Significant quantities of glycerin are used for printing masses, glycerin gelatin, copying ink, parchment and bookbinding paper; in the pharmaceutical industry - for various cosmetics and medicines(glucosal, glycerophosphates); in the paint industry - for the preparation of certain dyes (alizarin blue, benzanthrone dyes). The worst grades of glycerin are used for shoe polish. The residue after distillation of glycerin is used as an insulating material in the manufacture of electrical cables.
Annual world production glycerol exceeds 72,000 tons. In Russia in 1912 it reached 5 thousand tons, and 30-40% of the total output was exported to Germany, France and America. Interrupted by the war and the blockade, the export of glycerin from the USSR resumed in 1926/27. The total production of glycerin in the USSR, according to 1925/26 data, was 3.5 thousand tons, and in 1926/27 in the 3rd quarter alone it reached 896.5 tons for technical glycerin and for chemical and dynamite glycerin 487.1 t.