Углерод дисульфид

Описание

For many years, carbon disulfide was manufactured by the reaction of charcoal with sulfur vapor at temperatures of 750– 1000
C, but by the mid-twentieth century, especially in the United States, the process was superseded by the reaction of natural gas (principally methane) with sulfur.

Химические свойства

Carbon disulfide (carbon bisulfide; CS2; CASRN 75-15-0), in its pure form is a colorless liquid that evaporates readily at room temperature, with a sweet aromatic odor similar to that of chloroform. In its impure commercial and reagent form, however, carbon disulfide is a yellowish liquid with a foulsmelling odor. It can be detected by odor at about 1 ppm but the sense of smell fatigues rapidly and, therefore, odor does not serve as a good warning property. It has a vapor pressure of 297mmHg and solubility in water by weight of 0.3% at 20 °C (68 °F). Once carbon disulfide is in the air it will break down into simpler substances within a few days after release (OEHHA, 2001).

Физические свойства

Clear, colorless to pale yellow liquid; ethereal odor when pure. Technical grades have strong, foul, rotten, radish-like odor. Leonardos et al. (1969) reported an odor threshold in air of 210 ppb_v.

Использование

Carbon disulfide is used as a raw material in the production of such things as rayon, cellophane, semiconductors, and carbon tetrachloride, and to make some pesticides. It is used as an industrial solvent and chemical intermediate to dissolve rubber to produce tires (ATSDR, 1996), as well as in grain fumigation, analytical chemistry research, degreasing, dry cleaning, and oil extraction (Finkel et al., 1983). Natural sources of carbon disulfide include the open ocean, coastal areas of high biological activity, microbial reduction of sulfates in soil, marshlands, and some higher plants where the source of carbon disulfide is the tree roots (Carroll, 1985; Khalil and Rasmussen, 1984).
Previously, carbon disulfide was used as a pesticide, where it was typically mixed with carbon tetrachloride in a 20/80 mixture, respectively. This mixture was used to exterminate insects and rodents from entire boxcars of wheat, corn, rye, and other grains (Peters et al., 1988). Grain fumigators can be acutely intoxicated and may be chronically exposed to carbon disulfide. Therefore, in the late 1980s, all pesticides containing carbon disulfide as an active ingredient were cancelled by the United States Environmental Protection Agency (U.S. EPA) (U.S. EPA, 1999).

Подготовка

Carbon disulfide is manufactured by heating sulfur vapor with charcoal, and condensing vapors of the compound formed. Alternatively, it may be obtained by heating sulfur with natural gas or petroleum fractions. Instead of sulfur, H2S may be used. The reaction occurs at very high temperatures. The product obtained in these reactions may contain sulfur impurities. Carbon disulfide is purified by distillation.

Общее описание

Pure carbon disulphide is a colourless liquid with a pleasant odour similar to that of chloroform, while the impure carbon disulphide is a yellowish liquid with an unpleasant odour, like that of rotting radishes. Exposure to carbon disulphide occurs in industrial workplaces. Industries associated with coal gasification plants release more of carbon disulphide, carbonyl sulphide, and hydrogen sulphide. Carbon disulphide is used in large quantities as an industrial chemical for the production of viscose rayon fibres. In fact, the major source of environmental pollution both indoor and outdoor by carbon disulphide is caused by emission released into the air from viscose plants.

Реакции воздуха и воды

Highly flammable. Insoluble in water.

Профиль реактивности

Carbon disulphide has an extremely low autoignition temperature (125°C). May ignite or even explode when heated. The vapor or liquid has been known to ignite on contact with steam pipes, particularly if rusted [Anon., J. Roy. Inst. Chem., 1956, 80, p.664]. Explosion hazard when exposed to flame, heat, sparks or friction. Mixtures with lithium, sodium, potassium or dinitrogen tetraoxide may detonate when shocked. Potentially explosive reaction with nitrogen oxide, chlorine, permanganic acid(strong oxidizing agents). Vapor ignites in contact with aluminum powder or fluorine. Reacts violently with azides, ethylamine ethylenediamine, ethylene imine. Emits highly toxic fumes of oxides of sulfur when heated to decomposition [Bretherick, 5th ed., 1995, p. 663]. Sodium amide forms toxic and flammable H2S gas with CS2. (714)

Опасность

A poison. Toxic by skin absorption. Highly flammable, dangerous fire and explosion risk, can be ignited by friction. Explosive limits in air 1–50%. Questionable carcinogen. Peripheral ner- vous system impairment.

Пожароопасность

Ignition temperature dangerously low: 212F. Vapors may be ignited by contact with ordinary light bulb, when heated to decomposition, Carbon disulphide emits highly toxic fumes of oxides of sulfur. When heated to decomposition, emits highly toxic fumes of sulfur oxides and can react vigorously with oxidizing materials. Avoid air, rust, halogens, metal azides, metals, oxidants; when exposed to heat or flame reacts violently with aluminum, chlorine, azides, hypochlorite, ethylamine diamine, ethylene imine, fluorine, metallic azides of lithium, potassium, cesium, rubidium and sodium, nitrogen oxides, potassium, zinc and (sulfuric acid plus permanganate). Decomposes on standing for a long time.

Воспламеняемость и взрывоопасность

Carbon disulfide is extremely flammable and is a dangerous fire hazard (NFPA rating = 3). It is has a high vapor pressure and extremely low autoignition temperature. Its vapor is heavier than air and can travel a considerable distance to a source of ignition and flash back. The vapor forms explosive mixtures in air at concentrations of 1.3 to 50%. Carbon disulfide can be ignited by hot surfaces such as steam baths that would ordinarily not constitute an ignition source for other flammable vapors. Rust (iron oxide) may increase the likelihood of ignition by hot surfaces. Carbon disulfide fires should be extinguished with CO2 or dry chemical extinguishers.

Возможный контакт

Carbon disulfide is used in the manufacture of viscose rayon; ammonium salts; carbon tetrachloride; carbanilide, xantho genates; flotation agents; soil disinfectants; dyes; electronic vacuum tubes; optical glass; paints, enamels, paint removers; varnishes; varnish removers; tallow, textiles, explosives; rocket fuel; putty; preservatives, and rubber cement; as a solvent for phosphorus, sulfur, selenium, bromine, iodine; alkali cellulose; fats, waxes, lacquers, camphor, resins, and cold vulcanized rubber. It is also used in degreasing; chemical analysis; electroplating; grain fumigation; oil extraction; and drycleaning. It is widely used as a pesticide intermediate.

Экологическая судьба

Chemical/Physical. Carbon disulfide hydrolyzes in alkaline solutions to carbon dioxide and hydrogen disulfide (Peyton et al., 1976).
In an aqueous alkaline solution containing hydrogen peroxide, dithiopercarbonate, sulfide, elemental sulfur and polysulfides may be expected to form (Elliott, 1990). In an aqueous alkaline solution (pH ≥8), carbon disulfide reacted with hydrogen peroxide forming sulfate and carbonate ions. However, when the pH is lowered to 7–7.4, colloidal sulfur is formed (Adewuyi and Carmichael, 1987).
An aqueous solution containing carbon disulfide reacts with sodium hypochlorite forming carbon dioxide, sulfuric acid and sodium chloride (Patnaik, 1992). Forms a hemihydrate which decomposes at –3°C (Keith and Walters, 1992).Agricultural fumigant Burns with a blue flame releasing carbon dioxide and sulfur dioxide (Windholz et al., 1983). Emits very toxic sulfur oxides when heated to decomposition (Lewis, 1990). Carbon disulfide oxidizes in the troposphere producing carbonyl sulfide. The atmospheric half-lives for carbon disulfide and carbonyl sulfide were estimated to be approximately 2 years and 13 days, respectively (Khalil and Rasmussen, 1984).

хранилище

carbon disulfide should be used only in areas free of ignition sources (including hot plates, incandescent light bulbs, and steam baths), and this substance should be stored in tightly sealed metal containers in areas separate from oxidizers.

Перевозки

UN1131 Carbon disulfide, Hazard Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous materials.

Методы очистки

Shake it for 3hours with three portions of KMnO4 solution (5g/L), twice for 6hours with mercury (to remove sulfide impurities) until no further darkening of the interface occurs, and finally with a solution of HgSO4 (2.5g/L) or cold, saturated HgCl2. Dry it with CaCl2, MgSO4, or CaH2 (with further drying by refluxing over P2O5), followed by fractional distillation in diffuse light. Alkali metals cannot be used as drying agents. It has also been purified by standing with bromine (0.5mL/L) for 3-4hours, shaking rapidly with KOH solution, then copper turnings (to remove unreacted bromine), and drying with CaCl2. CS2 is highly TOXIC and highly FLAMMABLE. Work in a good fumehood. Small quantities of CS2 have been purified (including removal of hydrocarbons) by mechanical agitation of a 45-50g sample with a solution of 130g of sodium sulfide in 150mL of H2O for 24hours at 35-40o. The aqueous sodium thiocarbonate solution is separated from unreacted CS2, then precipitated with 140g of copper sulfate in 350g of water, with cooling. After filtering off the copper thiocarbonate, it is decomposed by passing steam into it. The distillate is separated from H2O and distilled from P2O5. [Ruff & Golla Z Anorg Chem 138 17 1924, Beilstein 3 IV 395.]

Несовместимости

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Also incompatible with chemically active metals (such as sodium, potassium, zinc), azides, organic amines, halogens. May explosively decompose on shock, friction, or concussion. May explode on heating. The substance may spontaneously ignite on contact with air and on contact with hot surfaces, producing toxic fumes of sulfur dioxide. Reacts violently with oxidants to produce oxides of sulfur and carbon monoxide, and causing fire and explosion hazard. Attacks some forms of plastic, rubber, and coating.

Утилизация отходов

This compound is a very flammable liquid which evaporates rapidly. It burns with a Blue flame to carbon dioxide (harmless) and sulfur dioxide. Sulfur dioxide has a strong suffocating odor; 1000 ppm in air is lethal to rats. The pure liquid presents an acute fire and explosion hazard. The following disposal procedure is suggested: All equipment or contact surfaces should be grounded to avoid ignition by static charges. Absorb on vermiculite, sand, or ashes and cover with water. Transfer underwater in buckets to an open area. Ignite from a distance with an excelsior trail. If quantity is large, Carbon disulfide may be recovered by distillation and repackaged for use.

Меры предосторожности

During handling of carbon disulfi de, occupational workers require proper clothing, eye protection, and respiratory protection. Workers should use the chemical under trained management. On contact with the eyes, immediately fl ush with large amounts of water. On skin contact, the worker should quickly remove contaminated clothing and immediately call for medical attention