Methods for additional purification of carbon tetrachloride. Preparation of anhydrous pure organic solvents. Basic Precautions
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Distill substances at a temperature much lower than their boiling point. The essence of steam distillation lies in the fact that high-boiling, non-miscible or slightly miscible, i.e. Substances that are poorly soluble in water evaporate when water vapor is passed through them; they are then condensed together with steam in a refrigerator. In order to establish whether a substance is volatile with water vapor, a small amount of it must be heated in a test tube with 2 ml of water. Above this tube, the bottom of the second test tube is held, in which ice is placed. If the drops condensing on the cold bottom of the second tube are cloudy, then the substance is volatile with water vapor. Table 6 Data on some substances distilled with water vapor Substance Boiling point, 0С Content of pure substance of mixture of substance with substance in steam distillate, % Aniline 184.4 98.5 23 Bromobenzene 156.2 95.5 61 Naphthalene 218.2 99 .3 14 Phenol 182.0 98.6 21 Nitrobenzene 210.9 99.3 15 o-Cresol 190.1 98.8 19 The sequence of work is as follows. It is recommended to first heat the flask with liquid and water almost to a boil. This preheating is intended to prevent the volume of the mixture in the flask from expanding too much due to the condensation of water vapor during the distillation. In the future, the distillation flask can not be heated. When a strong stream of steam comes out of the steam generator, close the rubber tube put on the tee with a clamp, and start distillation with steam. A fairly strong jet of steam must pass through the liquid in the flask. A sign of the end of distillation is the appearance of a clear distillate (pure water). If the substance to be distilled has appreciable solubility in water (eg aniline), a small amount of clear distillate should be collected. At the end of the distillation, the clamp is opened and only after that the burners are extinguished (thereby eliminating the danger of liquid being drawn from the distillation flask into the steam generator). In the receiver, after distillation, two layers are obtained: water and organic matter. The latter is separated from the water in a separating funnel, dried in the usual way and distilled for final purification. Sometimes salting out and extraction are used to reduce the loss of a substance due to its partial solubility in water. High-boiling substances which are difficult to distill with steam having a temperature of 100°C may be distilled with superheated steam, unless there is a danger of decomposition of the substance at a higher temperature. Superheaters of various devices are used to form superheated steam. Typically, the steam from the steam generator enters a metal coil, which has a pipe for measuring the temperature and is heated by the flame of a strong burner. It is necessary to maintain a certain temperature of superheated steam in order to control the rate of distillation and avoid decomposition of the substance. The distillation flask should be immersed in an oil or metal bath heated to the required temperature, and the neck of the flask should be tightly wrapped with asbestos cord. If the distillation is carried out at temperatures above 120-130 ° C, it is necessary to connect successively first air and then water coolers to the distillation flask. The use of superheated steam makes it possible to increase the rate of distillation of hardly volatile substances many times over (Fig. 39). In contrast to conventional, simple distillation, during which steam and condensate pass through the apparatus once in a direction, in countercurrent distillation, or rectification, part of the condensate constantly flows towards the steam. This principle is implemented in distillation distillation columns. Rectification is a method of separating or purifying liquids with fairly close boiling points by distillation using special columns in which rising vapors interact with the liquid flowing towards them (phlegm), which is formed as a result of partial condensation of vapors. As a result of repeated repetition of the processes of evaporation and condensation, the vapor is enriched with a low-boiling component, and the phlegm, enriched with a high-boiling component, flows into a distillation flask. Efficient columns used in industry or research can separate liquids that differ in boiling point by less than 1°C. Conventional laboratory columns allow the separation of liquids with a boiling point difference of at least 10°C. The distillation column must be thermally insulated so that the processes occurring in it proceed under conditions as close as possible to adiabatic. With significant external cooling or overheating of the column walls, its correct operation is impossible. To ensure close contact of the vapors with the liquid, distillation columns are filled with a packing. As nozzles, glass beads, glass or porcelain rings, short pieces of glass tubes or stainless steel wires, glass spirals are used. Distillation columns are also used with a Christmas-tree tattoo of the “star” type. The efficiency of the column depends on the amount of phlegm supplied for irrigation. To obtain sufficient reflux, the distillation column must be connected to a condenser. The role of a condenser with partial condensation of vapors can be performed by a conventional dephlegmator. A simple setup for separating a mixture of liquids is shown in fig. 38.52 Condensers are widely used, in which complete condensation of all vapors passing through the column takes place. Such condensers are equipped with a distillate tap. Rectification can be carried out both at atmospheric pressure and in vacuum. As a rule, vacuum distillation is carried out for high-boiling or thermally unstable mixtures. Questions for control: 1. Tell the types and methods of distillation. 2. In what cases is distillation used at atmospheric pressure, at reduced pressure (in vacuum) and with steam. Why? 3. Tell the principle of operation and the device of a distillation device at atmospheric pressure. 4. Tell the principle of operation and the device of a distillation device with water vapor. Practical part 4.1.4.1. Distillation at atmospheric pressure Reagents: Purified substance. Equipment: simple distillation apparatus. Assemble the instrument for simple distillation at atmospheric pressure as shown in fig. 38. Fig. 38. Device for simple distillation: 1 - Wurtz flask; 2 - thermometer; 3 - descending Liebig refrigerator; 4 - allonge; 5 - receiving flask The distillation flask 1 is filled with a funnel to no more than two-thirds of the distilled liquid. Before filling the device, measure the volume or weight of the liquid. The distillation apparatus is assembled from dry, clean parts and fixed on tripods. Turn on water for cooling. A bath (water, oil) or a mantle heater is used as a heater. Controlling the temperature of the bath with the help of a second thermometer 2 fixed on a tripod, the heating is set to ensure uniform, slow boiling of the contents of the flask. No more than two drops of pure and transparent distillate per second should fall into the receiver. Only under such conditions does the thermometer in the flask show the temperature corresponding to the point of equilibrium between vapor and liquid; if the distillation is too fast, the vapors are easily overheated. The distillation temperature is recorded in a log. The distillation must not be continued to dryness! They finish it at the moment when the boiling point is 2-3 degrees higher than the one at which the main fraction passed. At the end of the distillation, the volume or weight of the distillate and the residue in the distillation flask are determined. Exercise. Purify one of the proposed solvents as directed by the instructor. In organic synthesis, the "purity" of the solvents used is very important. Often, even small impurities prevent the reaction from proceeding, so the purification of solvents is an urgent task for a synthetic chemist. Chloroform 0 20 Tboil = 61.2 C; nd=1.4455; d415=1.4985 Azeotropic mixture (chloroform-water-ethanol) contains 3.5% water and 4% alcohol, it boils at 55.5°C. Sales chloroform contains alcohol as a stabilizer that binds the phosgene formed during decomposition. Cleaning. Shake with concentrated sulfuric acid, wash with water, dry over calcium chloride and distill. Attention! Due to the risk of explosion, chloroform must not be brought into contact with sodium. Carbon tetrachloride 0 20 Tbp. = 76.8 C; nd =1.4603 Azeotropic mixture with water boils at 66°C and contains 95.9% carbon tetrachloride. A ternary azeotropic mixture with water (4.3%) and ethanol (9.7%) boils at 61.8°C. Cleaning and drying. A distillation is usually sufficient. The water is then removed as an azeotropic mixture (the first parts of the distillate are discarded). If high demands are placed on drying and purification, then carbon tetrachloride is refluxed for 18 hours with phosphorus oxide (V), distilled with a reflux condenser. Carbon tetrachloride must not be dried with sodium (risk of explosion!). Ethanol 0 Tbp.=78.33 C; nd20=1.3616;d415=0.789 Ethanol is miscible with water, ether, chloroform, benzene in any ratio. The azeotropic mixture with water boils at 78.17°C and contains 96% ethanol. A ternary azeotropic mixture with water (7.4%) and benzene (74.1%) boils at 64.85°C. 54 Impurities. Synthetic alcohol is contaminated with acetaldehyde and acetone, ethyl alcohol obtained during fermentation is contaminated with higher alcohols (fusel oils). Pyridine, methanol and gasoline are added for denaturation. Drying. In 1 liter of commercial "absolute" alcohol dissolve 7 g of sodium, add 27.5 g of diethyl ester of phthalic acid and reflux for 1 hour. Then distilled with a small column. Distilled alcohol contains less than 0.05 water. Traces of water can be removed from commercial "absolute" alcohol in another way: 5 g of magnesium is boiled for 2-3 hours with 50 ml of "absolute" alcohol, to which 1 ml of carbon tetrachloride is added, then 950 ml of "absolute" alcohol is added, another 5 is boiled h with reflux. In conclusion, they distill. Water detection. Alcohol containing more than 0.05% water precipitates a voluminous white precipitate from a benzene solution of aluminum triethylate. 4.1.4.2. Steam distillation Reagents: Purified substance. Equipment: simple distillation apparatus. Assemble the steam distillation apparatus as shown in fig. 39. Fig. 39. Device for distillation with water vapor: 1- steam generator; 2 - tee with clamp; 3 - distillation flask; 4 - refrigerator; 5 - allonge; 6 - receiving flask; 7 - safety tube; 8 - inlet tube; 9 - a tube that removes steam Steam is formed in the steamer 1 (a flask is also suitable instead of it). The safety tube 7 serves to equalize the pressure, the connecting link - to drain the condensate. The steam enters the distillation flask 3 through the supply tube 8, in which the mixture to be separated is located. Usually this flask is also heated. The distillate enters the refrigerator 4, condenses and flows through the allonge 5 into the receiver 6. Small amounts of the substance can be distilled without using a steamer, but by adding a certain amount of water directly into the distillation flask. Task 1. Conduct a steam distillation of natural raw materials (rose petals, spruce needles) in order to obtain an aqueous extract of essential oil. For this, natural raw materials are loaded into the flask, filled with water, and steam distillation is carried out. Task 2. Obtain anhydrous oxalic acid from its mixture with water by azeotropic distillation of water. The distillation of a mixture of two liquids insoluble in each other is also used for drying organic substances by the so-called azeotropic distillation of water. To this end, the substance to be dried is mixed with an organic solvent, such as benzene or carbon tetrachloride, and the mixture is subjected to heating in a distillation apparatus. In this case, water is distilled off with a vapor of organic matter (at a temperature that is lower than the boiling point of the lowest boiling component of the mixture, for example, benzene or CCl4). With a sufficiently large amount of organic solvent, complete dehydration of the dried substance can be achieved. 4.1.4.3. Rectification Reagents: Purified substance. Equipment: Apparatus for fractional distillation. Rectification at atmospheric pressure Assemble the distillation apparatus as shown in fig. 40. Fig. 40. Device for fractional distillation: 1 - distillation flask; 2 - dephlegmator; 3 - thermometer; 4 - refrigerator; 5 - allonge; 6 - receiving flask Task. Separate the mixture of ethanol and butanol into components by distillation at atmospheric pressure. Collect the following fractions: a) up to 82°C ("pure ethanol"); b) from 83 to 110°C (intermediate fraction); c) remainder. Measure the fraction and residue volume. 4.1.4.4. Distillation under vacuum Reagents: Purified substance. Equipment: Apparatus for distillation under reduced pressure. 56 Fig. 41. Device for distillation under reduced pressure: 1 - Claisen flask or round-bottomed flask with a Claisen nozzle; 2 - capillary connected to a rubber hose with a clamp; 3 - thermometer; 4 - refrigerator; 5 - allonge; 6 - receiving flask; 7 - safety bottle; 8 - manometer Task. Distill quinoline under reduced pressure. T bale. quinoline at atmospheric pressure -237.7 ° C, and at 17 mm Hg. Art. -114°C. Questions for the colloquium: 1. Why is a reflux condenser used in fractional distillation? 2. What are azeotropic mixtures? What are the methods of separating them? 3. At what temperature (above or below 100°C) will water boil in the mountains? Explain the answer. 4. Where do impurities remain during the purification of organic compounds by distillation? 4.1.5. Thin layer chromatography (TLC) Chromatography refers to a whole group of physicochemical separation methods based on the work of Tsveta (1903) and Kuhn (1931). Distinguish chromatography in columns, thin-layer, on paper, gas. The separation of substances in these cases occurs either as a result of distribution between two liquid phases (partition chromatography), or due to the different adsorbability of the substance by any adsorbent (adsorption chromatography). Chromatography in a thin layer is to use, for example, aluminum oxide as a sorbent. In this case, both distribution and adsorption play a role in separation. The mobile phase, in the flow of which the mixture being separated moves, is called the eluent, and the solution leaving the stationary phase layer and containing the dissolved components of the mixture is called the eluate. Depending on the direction in which the eluent moves across the plate, there are: ascending thin layer chromatography 57 descending thin layer chromatography horizontal thin layer chromatography radial thin layer chromatography. Ascending thin layer chromatography This type of chromatography is the most common and is based on the fact that the front of the chromatographic system rises along the plate under the action of capillary forces, i.e. the front of the chromatographic system moves from bottom to top. For this method, the simplest equipment is used, since any container with a flat bottom and a tight-fitting lid, into which a chromatographic plate can be freely placed, can be used as a chromatographic chamber. The method of ascending thin layer chromatography has a number of disadvantages. For example, the speed of the rise of the front along the plate occurs unevenly, i.e. in the lower part it is the highest, and as the front rises it decreases. This is due to the fact that in the upper part of the chamber the saturation with solvent vapors is less, therefore the solvent from the chromatographic plate evaporates more intensively, therefore, its concentration decreases and the speed of movement slows down. To eliminate this shortcoming, strips of filter paper are attached along the walls of the chromatographic chamber, along which the ascending chromatographic system saturates the chamber with vapor throughout the entire volume. Some chromatographic chambers have a division into two trays at the bottom. This improvement allows not only to reduce the consumption of the chromatographic system (less volume is required to obtain the required height of the chromatographic system), but also to use an additional cuvette for the solvent, which increases the saturation vapor pressure in the chamber. The need to monitor the solvent front can also be considered a disadvantage, since the solvent front line can “run away” to the upper edge. In this case, it is no longer possible to determine the actual value of Rf. Descending thin layer chromatography This chromatography method is based on the fact that the front of the chromatographic system descends along the plate mainly under the influence of gravity, i.e. the mobile phase front moves from top to bottom. For this method, a cuvette with a chromatographic system is attached to the upper part of the chromatographic chamber, from which a solvent enters the chromatographic plate using a wick, which flows down and the sample is chromatographed. The disadvantages of this method include the complexity of the equipment. This method is mainly used in paper chromatography. 58 Horizontal thin layer chromatography This method is the most complex in terms of instrumentation, but the most convenient. So, in the chromatographic chamber, the plate is placed horizontally and the system is fed to one edge of the plate using a wick. The solvent front moves in the opposite direction. There is another trick to simplify the camera as much as possible. To do this, an aluminum-based chromatographic plate is slightly bent and placed in the chamber. In this case, the system will act from two sides at the same time. Only aluminum-backed plates are suitable for this purpose, since the plastic and glass bases are "inflexible", i.e. does not retain its shape. The advantages of this method include the fact that in a horizontal cell the saturation of the system with vapor occurs much faster, the front velocity is constant. And when chromatographing from both sides, the front does not "run away". Radial thin-layer chromatography Radial thin-layer chromatography consists in the fact that the test substance is applied to the center of the plate and the eluent is fed there, which moves from the center to the edge of the plate. The distribution of the components of the mixture occurs between the water absorbed by the carrier1 and the solvent moving through this stationary phase (mobile phase). In this case, Nernst's law applies. The component of the mixture that is more readily soluble in water moves more slowly than the one that is more readily soluble in the mobile phase. Adsorption lies in the fact that adsorption equilibria are established between the carrier and the components of the mixture - each component has its own, resulting in a different speed of movement of the components. A quantitative measure of the rate of transfer of a substance when using a specific adsorbent and solvent is the value of Rf (deceleration factor or mobility coefficient). The value of Rf is defined as the quotient of the distance from the spot to the start line divided by the distance of the solvent (front line) from the start line: Distance from the spot to the start line Rf = Distance from the solvent front to the start The value of Rf is always less than unity, it does not depend on the length chromatograms, but depends on the nature of the selected solvent and adsorbent, temperature, concentration of the substance, the presence of impurities. So at low temperatures, substances move more slowly than at higher temperatures. Contaminants contained in the mixture of solvents used, the inhomogeneity of the adsorbent, foreign ions in the analyzed solution can change the value of Rf. 1 The carrier is an adsorbent, eg alumina, starch, cellulose, and water form the stationary phase. 59 The factor Rs is sometimes used: Distance traveled by the substance from the line to the start Rs= Distance traveled by the substance taken as a standard from the line to the start Unlike Rf, the value of Rs can be greater or less than 1. The value of Rf is determined by three main factors. FIRST FACTOR - the degree of affinity of the chromatographed organic compound to the sorbent, which increases in the following series: alkanes< алкены < простые эфиры < нитросоединения < альдегиды < нитрилы < амиды < спирты < тиофенолы < карбоновые кислоты По мере увеличения числа функциональных групп энергия адсорбции возрастает (Rf уменьшается). Наличие внутримолекулярных взаимодействий, например водородных связей, наоборот уменьшает ее способность к адсорбции (Rf увеличивается). Так, о-нитрофенолы и о-нитроанилины имеют большее значение Rf , чем м- и п-изомеры. Плоские молекулы адсорбируются лучше, чем неплоские. ВТОРОЙ ФАКТОР - свойства самого сорбента, которые определяются не только химической природой вещества, но и микроструктурой его активной поверхности. В качестве сорбентов чаще всего используются оксид алюминия, силикагель, гипс с размером гранул 5-50 мкм. Оксид алюминия обладает удельной поверхностью 100- 200 м2/г, имеет несколько адсорбционных центров. Одни из них избирательно сорбируют кислоты, другие - основания. При этом для кислот c рКа <5 и оснований c рКа >9 is characterized by chemisorption. Aluminum oxide is also effective for separating acyclic hydrocarbons with various numbers of double and triple bonds. Silica gel (SiO2×H2O) has a much higher sorption capacity than aluminum oxide. Large-pore grades of silica gel with a pore size of 10–20 nm and a specific surface area of 50–500 m2/g are used in TLC. Silica gel is chemically inert to most active organic compounds, however, due to its acidic properties (pH 3-5), it sorbs bases with pKa>9 quite strongly. Gypsum is a sorbent with a small sorption capacity and low activity. It is used for chromatography of polar compounds, as well as compounds containing a large number of different functional groups. THE THIRD FACTOR is the nature of the eluent that displaces the molecules of the studied substances adsorbed on the active centers. In order of increasing eluting power, the eluents can be arranged in the following row: 60
Physical and chemical properties:
Carbon tetrachloride (tetrachloromethane, CHCl 4) is a colorless liquid. Solv. water in CCl 4 about 1% (24°). Does not ignite. On contact with flames or incandescent objects, it decomposes to form phosgene. May contain impurities CS 2 , HCl, H 2 S, organic sulfides.
Application area:
Used as a solvent; for extraction of fats and alkaloids; in the production of freons; in fire extinguishers; for cleaning and degreasing clothes in everyday life and production conditions.
Receipt:
Obtained by chlorination of CS 2 in the presence of catalysts; catalytic chlorination of CH 4 (together with CH 2 C1 2 and CHCl 3); by heating a mixture of coal and CaCl 2 at the temperature of a voltaic arc.
The general nature of the toxic effect:
A narcotic with less potent vapor than chloroform. By any route of entry, it causes severe liver damage: centrilobular necrosis and fatty degeneration. At the same time, it also affects other organs: the kidneys (the proximal parts of the renal tubules), the alveolar membranes and the vessels of the lungs. Lesions in the kidneys and lungs are less significant, they develop, as a rule, after liver damage and as a result of a general metabolic disorder, but in some cases they play a significant role in the picture and outcome of poisoning. The earliest sign of toxic action is considered to be a change in the level of a number of blood enzymes. A large ability of the liver to regenerate after poisoning was revealed. The intake of alcohol during the inhalation of Ch. W. vapors, cooling, and an increased oxygen content in the air increase the toxic effect. When extinguishing a flame with fire extinguishers and in general with strong heating, poisoning can occur from inhalation of thermal decomposition products C.U.
According to existing views on the pathogenesis of the toxic action of Ch. W., it is associated with free radical metabolites (such as CC1 h), which are formed as a result of the hemolytic rupture of CCl 4 molecules. As a result of increased peroxidation of lipid complexes of intracellular membranes, enzyme activity is disrupted, a number of cell functions (protein synthesis, ß-lipoprotein metabolism, drug metabolism), nucleotide destruction occurs, etc. It is assumed that the main site for the formation of free radical metabolites is the endoplasmic reticulum and microsomes cells.
Picture of poisoning:
When very high concentrations are inhaled (when careless entry into tanks and reservoirs, when extinguishing fires with CW fire extinguishers in small enclosed spaces, etc.), either sudden death, or loss of consciousness or anesthesia are possible. With milder poisoning and a predominance of action on the nervous system, headache, dizziness, nausea, vomiting, confusion or loss of consciousness are characteristic. Recovery occurs relatively quickly. Excitation is sometimes in the nature of strong attacks of a violent state. Described poisoning in the form of encephalomyelitis, cerebellar degeneration, peripheral neuritis, optic neuritis, hemorrhage and fat embolism of the brain. There is a known case of epileptiform convulsions and loss of consciousness on the 4th day after poisoning without significant damage to the liver and kidneys. At the autopsy (in case of rapid death) - only hemorrhages and cerebral edema, pulmonary emphysema.
If poisoning develops slowly, severe hiccups, vomiting, often prolonged, diarrhea, sometimes intestinal bleeding, jaundice, and multiple hemorrhages join the symptoms of damage to the central nervous system within 12-36 hours. Later - an increase and soreness of the liver, severe jaundice. Still later, symptoms of severe kidney damage appear. In other cases, symptoms of kidney damage precede signs of liver disease. Observations have shown that liver damage is pronounced in the first period and the stronger, the faster death occurs; with later death, there are already regenerative processes in the liver tissue. Changes in the kidneys during early death are insignificant. With kidney damage, the amount of urine decreases; in the urine - protein, blood, cylinders. In the blood, the content of non-protein nitrogen is increased, but the content of chlorides, calcium, and proteins is lowered. In severe cases, oliguria or complete anuria occurs (both filtration and secretory functions of the kidneys are impaired). High blood pressure, edema, seizures, uremia - Pulmonary edema may develop, often the immediate cause of death (sometimes edema is explained by the administration of excess fluid during treatment). In more favorable cases, after anuria - profuse diuresis, gradual disappearance of pathological elements in the urine, complete restoration of kidney function. Sometimes, apparently at not very high concentrations of C.U., the only sign of poisoning may be a decrease or cessation of urine output.
The consequence of acute poisoning with Ch. W. vapors can be a duodenal ulcer, pancreatic necrosis, anemia, leukocytosis, lymphopenia, changes in the myocardium, acute psychosis (Vasilyeva). The outcome of poisoning can be yellow atrophy of the liver, as well as its cirrhosis.
When Ch. W. is taken orally, the picture of poisoning is the same as when the vapors are inhaled, although there are indications that the liver is predominantly affected in these cases.
The most characteristic pathological changes are: parenchymal and fatty degeneration of the liver, as well as numerous necrosis in it; acute toxic nephrosis; nephrosonephritis (the tubules of the kidneys are affected throughout their entire length); swelling of the brain; inflammation and pulmonary edema; myocarditis.
Toxic concentrations causing acute poisoning.
For humans, the threshold for odor perception is 0.0115 mg/l, and the concentration that affects the light sensitivity of the eye is 0.008 mg/l (Belkov). At 15 mg / l after 10 minutes, headache, nausea, vomiting, increased heart rate; at 8 mg/l the same after 15 minutes, and at 2 mg/l after 30 minutes. Fatigue and drowsiness were observed in workers at an 8-hour exposure to a concentration of 1.2 mg/l. When cleaning the floor of Ch. W. (concentration in the air 1.6 mg / l), the worker felt a headache, dizziness after 15 minutes and was forced to leave work. The poisoning was fatal (the victim was an alcoholic). Described mass poisoning when cleaning the evaporator coils on the ship (air concentration 190 mg/l). The victims, with the exception of one, survived. Exposure to a concentration of 50 mg / l by inhalation for 1 hour can be fatal. Severe poisoning is known with damage to the liver, kidneys and intestinal bleeding when working 2 shifts in a row under normal conditions for washing devices.
When ingested, 2-3 ml of CW may already cause poisoning; 30-50 ml lead to severe and fatal intoxication. Cases of mass poisoning with 20 deaths are described when ingesting a hair wash containing 1.4% Ch. W. (the rest is alcohol). The victims - bronchitis, pneumonia, hematemesis, diarrhea, liver and kidney damage. However, there is a known case of recovery after taking 220 ml of Ch. W. with developed anesthesia and severe kidney failure. Paraffin (vaseline) oil was used for gastric lavage.
In chronic poisoning in relatively mild cases, there is: fatigue, dizziness, headache, pain in different parts of the body, muscle tremors, memory impairment, inertia, weight loss, heart disorders, irritation of the mucous membranes of the nose and throat, dysuric disorders. The most common complaints are abdominal pain, lack of appetite, nausea. Enlargement and tenderness of the liver are found; change in motility, spasms of different parts of the intestine, bilirubinemia, etc.
On the skin, carbon tetrachloride can cause dermatitis, sometimes eczema, and urticaria. Irritates the skin more than gasoline. When the thumb is immersed in Ch, W, for 30 minutes, after 7-10 minutes, a feeling of cold and burning appears. After ersepoicia, erythema disappears after 1-2 hours. A case of polyneuritis is described as a result of constant contact of C. W. with the skin during work. In large quantities, it penetrates through burnt skin; probably "poisoning is possible when extinguishing clothes burning on people with the help of C. W.
Urgent care.
In case of acute inhalation poisoning - fresh air, rest. Prolonged inhalation of humidified oxygen using nasal catheters (continuous during the first 2-4 hours; subsequently, 30-40 min with breaks of 10-15 minutes). Heart remedies: camphor (20%), caffeine (10%). cordiamine (25%) 1-2 ml subcutaneously; sedatives, strong sweet tea. Intravenously inject 20-30 ml of 40% glucose solution with 5 ml of 5% ascorbic acid, 10 ml of 10% calcium chloride solution. With hiccups, vomiting - intramuscularly 1-2 ml of a 2.5% solution of chlorpromazine with 2 ml of a 1% solution of novocaine. With respiratory depression - inhalation of carbogen repeatedly for 5-10 minutes, intravenously 10-20 ml of a 0.5% solution of bemegride, subcutaneously 1 ml of a 10% solution of corazol. With a sharp weakening (stopping) of breathing - artificial respiration by the method of "mouth to mouth" with the transition to controlled. In severe cases, immediate hospitalization in the intensive care center.
When taking the poison inside - a thorough gastric lavage through a tube, a universal antidote (TUM), 100-200 ml of vaseline oil, followed by giving a saline laxative; bowel cleansing to clean washing water (siphon enema); Bloodletting (150-300 ml) followed by partial blood replacement. To enhance diuresis, the introduction into a vein of 50-100 ml of 30% urea in 10% glucose solution or 40 mg of lasix. With the development of a collaptoid state, intravenously 0.5 ml of a 0.05% solution of strophanthin in 10-20 ml of a 20% glucose solution, or corglicon (0.5-1 ml of a 0.06% solution in 20 ml of a 40% glucose solution); according to indications - mezaton. In the future, to restore the acid-base balance - intravenous drip injection of 300-500 ml of 4% sodium bicarbonate solution. Recommended vitamins B6 and C, lipoic acid, unitiol (5% solution intramuscularly, 5 ml 3-4 times a day on the first day, 2-3 times a day on the second and third days).
Contraindicated: sulfa drugs, adrenaline and chlorine-containing hypnotics (chloral hydrate, etc.). We do not allow the intake of alcohol and fats!
Based on material from the book: Harmful substances in industry. Handbook for chemists, engineers and doctors. Ed. 7th, per. and additional In three volumes. Volume I. Organic substances. Ed. honored activity science prof. N.V. Lazareva and Dr. honey. Sciences E. N. Levina. L., "Chemistry", 1976.
UNION OF THE SOVIET SHIRISH EDERRESPUBLIK 07 S 07 S 19/06 RETENII RSKOY I wish to promote the development of xo zoldnazol, ORS 12 in general k ots-Khkhloushkin n and the state konitet of the USSR MADE INVENTION AND O 3 NRTU DESCRIPTION OF INORGANIC CHEMISTRY. , and electrochemistry of the Academy of Sciences of the Georgian SSR "Foreign Literature", 1958, p. 393-396.2. Workshop on organic chemistry, I., "Iir", 1979, p. 376 (prototype) 3 E.N.Napvop, S.E.Ie 1 oap-"Zpot 8.pcs 1.sev. 1 eiyeg", 971, p.461-472..80295 4) (57) METHOD OF CLEANING , FOUR CARBON by drying with a desiccant and distillation, it is noted that, for the purpose of the process technology and the degree of drying, a mixture of the complete formula CoK C 1 + Soy where 11- benz, 1,3- tnadi1 - benzo, 1,3-selenium at a mass ratio: Co K C 1 (25-30): in the presence of a mixture of 2.0-3.0 to the original fourth carbon, and the stages of oregonka are combined in time. 117295 2nd includes the stage of boiling solvent at reflux for 18 hours using P O as a drying agent, followed by 5 column distillation. The consumption of P 05 per 1 liter of solvent is 25-30 g, and the water content in the target product is not lower than 0.00523.0 The disadvantages of the known method are complexity 1, the presence of two stages - drying and distillation and the duration of the process, which significantly complicates its technology, also 15 high water content in the target product. The purpose of the invention is to simplify the process technology and increase the degree of drying. Water is the main undesirable impurity of SS and therefore all purification methods usually include the stage of drying and solvent distillation. (0.08%) and in many cases for eyes distillation suffices. Water is removed in the form of a zeotropic mixture, which boils at 6 °C and contains 95.9 solvents. A ternary azeotropic mixture of vault (4.3%) and ethanol (9.7) boils at 61.8 C. When higher requirements are made for the purification of SS 1, distillation without preliminary drying of the solvent is unsuitable. There is a known method for purifying carbon tetrachloride, according to which SS 1 is pre-dried and then distilled on a column. Drying is carried out over CaC 1, and distillation of ad P 05 CC 1, dried over calcined CaC 1 and distilled from a flask with an effective reflux 0r in a water bath, and in some cases - from a quartz flask with a reflux condenser. When using SS 14, for thermochemical measurements, the solvent is subjected to fractional distillation twice on a column with a vacuum jacket, each time discarding the first and last portion of a quarter of the total amount of distillate G 1. However, simple distillation of the solvent without the use of desiccants does not allow obtaining a solvent with a low water content. In methods based on the use of desiccants and subsequent distillation, a preliminary long-term contact of the solvent with a desiccant is necessary, the choice of which for CC 1 is limited. Among the desiccants, calcined CaC 1 is the most acceptable. It has been shown that 50CC 1 cannot be dried over sodium, since an explosive mixture is formed under these conditions. This purification method is lengthy, has many steps, and is ineffective.55 The method closest to the invention is the purification method for CC 1, which is 1 where d "benz, 1,3-thiadiaeol; k - benz, 1,3-selenediazol; at a mass ratio of Co KS 1Co K., C 1 25" 30: 1 and the total amount of the mixture is 2.0-3.0 wt, .G with respect to the initial carbon tetrachloride, and the stages of drying and distillation are combined in time and space. the indicated ligands Pu K) quantitatively decompose in the presence of traces of water. These complexes are insoluble in all ordinary solvents. - solvents. In solvents with water impurities, instead of the usual dissolution, the destruction of the complex occurs with the formation of a free ligand. and a hydrated cobapt ion, In solvents containing trivalent in the molecule a nitrogen atom, the reaction of substitution of ligand molecules by solvent molecules proceeds. Such solvents include amines, amides, and iitriles, as well as some heterocycles. sulfur- or selenium-containing diazoles, using the polarography method, as well as UV and visible spectra of the resulting solutions, it was shown that the interaction between the ligand and the complexing agent in nitrogen-containing media or in media containing traces of water does not take place. Complexes of cobalt with aromatic diazoles can only be obtained in absolutely anhydrous media that do not contain a nitrogen atom. In all cases, when these complexes are introduced into solvents containing moisture impurities, the sum of the spectra of the ligand and the cobapt ion corresponds to the resulting spectrum, and the polarograms clearly show the waves of lgand and the cobalt ion. 25 The reaction of the decomposition of cobapt complexes with these diazoles under the action of water molecules proceeds very quickly and the solvent takes on the color of a hydrated cobalt ion. Instant binding of traces of water by a desiccant (cobapt complexes proceeds by the mechanism of hydrate formation, hydrate (transfer of the coordinated cobalt atom in the complex to hdratnro-3 5. bathed non is dissolved; therefore, the coloring of the solvent in the color of gnd, rated cobolt ions can serve as a characteristic sign of the removal of water impurities from a solvent, It is known that an anhydrous solid has a pale blue color of di-, -tri-, tetra- and hexahydrates, respectively, violet, purple, red and red-brown. 14, depending on the amount of water in 50 it, the solvent is colored in one of the indicated colors of hydrated Co. The ability of complexes of cobap "ta with benz,1,3-thia- and selenediazol" to be destroyed in the presence of traces of 55 water depends on the nature of the ligand, more precisely on the nature of the key heteroatom in the ligand molecule. however, it depends on the nature of the heteroatom (R, Re) in the ligand and increases significantly when the sulfur atom is replaced by a selenium atom in the diazole hetero ring. At a very low water content in SS 1, the most effective desiccant is a cobalt complex with benz,1,3-selenpiaeol. When the water content in the solvent does not exceed 0.013, the complex of cobalt with benz,1,3-tiddiaeol can also serve as a drying agent. Consequently, a mixture of these complexes can serve as a drying agent in a wide range of water content in the solvent. the cobalt complex with benz,1,3-selenediaol can be mixed as an impurity to the cobalt complex with benzo,1,3-thiadiazole, which will bind most of the water in the solvent. The required degree of purification of SS 1 in each particular case can be achieved by varying the proportion of the components of the mixture. However, in order for the composition to have maximum efficiency as a drying agent, it is necessary to use the minimum weight fraction of the cobalt complex with benz,1,3-selenediaeol in the mixture. Thus, along with the effect of hydrate formation from the anhydrous cobalt complex, which is an easy basis for the proposed method, the composition of the drying mixture of cobalt complexes with aromatic diazoles is a characteristic feature of this SS 14 purification method. Instant binding of traces of water by cobalt complexes based on these diaeols when they are introduced into SS 14 eliminates the need for preliminary 18-hour reflux of the solvent over PO. Therefore, a mixture of complexes can be introduced into the solvent directly at the distillation stage, thereby combining the stages of drying and distillation The decomposition products of the complexes - the aromatic diaeol ligand and the hydrated cobalt ion have a much higher boiling point than SS, therefore, during distillation, they cannot turn into a distillate. thiadiaeol and bene,1,3-selenediaeol. The results are shown in the table, in order to prevent contact of the distillate with air. The excess mixture of cobalt complexes with diaeols, when introduced into CC 1, settles at the bottom of the flask of the distillation apparatus, in which the purified solvent retains the color of the hydrated cobalt ion until the end of the process. Water content in the distillate is determined by standard Fleur titration. EXAMPLE 1. 300 mp CC+ are introduced into the flask of the distillation apparatus, a mixture consisting of 10 g of a cobolt complex with beneo,1,3-thiadiazole and O, 4 g is added cobalt complex with benzoate with 2,1,3-selenediazole (the total amount of a mixture of cobalt complexes 23 and distilled. A fraction is taken with bp, 76.5-77.0 C ("200 MP). The first fraction with bp up to 76 .5 C 2 is discarded (30 MP) Water content in the distillate 0.00073, Speed of change 5 MP/min Duration t-O 3 0750 10: 15:1.0007 25 30 0.0005 0 , the invention provides a simplification of the process technology due to the elimination of the preliminary contact stage solvent Z 0 with a desiccant, the stages of drying and distillation are combined in time and space, reducing the time required for cleaning SS 1 due to the rapid binding of traces of water in the solvent with a mixture of cobalt complexes with aromatic dia, eols, and achieving a drying depth of SS 1, up to 0.00053 residual water, which increases the degree of drying by an order of magnitude, Ce vnoarat, from 14 g of 2 1,3-ticobalion (general cobalt is added to the stake adiagold complex with ben, the amount is fraction "200 mn)e 0.0005 F Prodol Xs t won by a child of a child Compiled by A. Arteedaktor N. Dzhugan Techred I. Astvlosh Correction V, Vutyaga Circulation 409 of the State Committee for Acquisitions and Discoveries, Zh, Raushskaya n snoe d. P P, Patent Law. 4 measures 2, 300 MP bu distillation an mixture consisting of cobapta with beneo and 0.4 g of a complex of o,1,3-selendiae about a mixture of complex is distilled, Selected ip. up to 76.5-77 OS e of water in the distillation distillation 5 cp / mi t process. measures 3-8. The process for example 2 with a different order 7145/16 VNIIII Gosu on cases 113035, Ios
Request
3521715, 16.12.1982
INSTITUTE OF INORGANIC CHEMISTRY AND ELECTROCHEMISTRY AS GSSR
TSVENIASHVILI VLADIMIR SHALVOVICH, GAPRINDASHVILI VAKHTANG NIKOLAEVICH, MALASHKHIA MARINA VALENTINOVNA, HAVTASI NANULI SAMSONOVNA, BELENKAYA INGA ARSENEVNA
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Carbon tetrachloride purification method
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