Циклогексан

Описание

Cyclohexane is obtained by the distillation of petroleum or by hydrogenation of benzene. It constitutes 0.5–1.0% of petroleum

Химические свойства

Cyclohexane is a colorless liquid with a mild, sweet odor.

Физические свойства

Colorless liquid with a sweet, chloroform-like odor. A detection odor threshold concentration of 2,700 mg/m³ (784 ppm_v) was experimentally determined by Dravnieks (1974). An odor threshold concentration of 2.7 ppb_v was reported by Nagata and Takeuchi (1990).

Использование

Solvent for lacquers and resins. Paint and varnish remover. In the extraction of essential oils. In analytical chemistry for mol wt determinations (cryoscopic constant 20.3). In the manufacture of adipic acid, benzene, cyclohexyl chloride, nitrocyclohexane, cyclohexanol and cyclohexanone. In the manufacture of solid fuel for camp stoves. In fungicidal formulations (possesses slight fungicidal action). In the industrial recrystallization of steroids.

Определение

A colorless liquid alkane that is commonly used as a solvent and in the production of hexanedioic acid (adipic acid) for the manufacture of nylon. Cyclohexane, itself, is manufactured by the reformation of longer chain hydrocarbons present in crude-oil fractions. It is also interesting from a structural point of view, existing as a ‘puckered’ six-membered ring, having all bonds between carbon atoms at 109.9° (the tetrahedral angle). The molecule undergoes rapid interconversion between two ‘chair-like’ CONFORMATIONS, which are energetically equivalent, passing through a ‘boat-like’ structure of higher energy. It is commonly represented by a hexagon.

Методы производства

Cyclohexane is fractionated from crude oil and may be released wherever petroleum products are refined, stored, and used. Another large source of general release is in exhaust gases from motor vehicles. It is prepared synthetically from benzene, by hydrocracking of cyclopentane, or from toluene by simultaneous dealkylation and double bond hydrogenation.

Общее описание

A clear colorless liquid with a petroleum-like odor. Used to make nylon, as a solvent, paint remover, and to make other chemicals. Flash point -4°F. Density 6.5 lb / gal (less than water) and insoluble in water. Vapors heavier than air.

Реакции воздуха и воды

Highly flammable. Insoluble in water.

Профиль реактивности

Liquid nitrogen dioxide was fed into a nitration column containing hot Cyclohexane, due to an error. An explosion resulted [MCA Case History 128(1962)] Incompatible with strong oxidizers.

Угроза здоровью

Cyclohexane is an acute toxicant of loworder. It is an irritant to the eyes and respiratorysystem. Exposure to a 1–2% concentrationin air caused lethargy, drowsiness,and narcosis in test animals. The lethal concentrationfor a 1-hour exposure in mice isestimated at around 30,000 ppm. Ingestionof cyclohexane exhibited low toxic effects intest species. The LD50 values in the literature show a wide variation. It may be detectedfrom its odor at 300 ppm concentration.

Химическая реактивность

Reactivity with Water: No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Профиль безопасности

Poison by intravenous route, Moderately toxic by ingestion. A systemic irritant by inhalation and ingestion. A skin irritant. Mutation data reported. Flammable liquid. Dangerous fire hazard when exposed to heat or flame; can react with oxidming materials. Moderate explosion hazard in the form of vapor when exposed to flame. When mixed hot with liquid dinitrogen tetraoxide an explosion can result. To fight fire, use foam, CO2, dry chemical, spray, fog. When heated to decomposition it emits acrid smoke and fumes.

Возможный контакт

Cyclohexane is used as a chemical intermediate; as a solvent for fats, oils, waxes, resins, cer- tain synthetic rubbers; and as an extractant of essential oils in the perfume industry.

Канцерогенность

No tumor-promoting activity was observed in mice receiving one 60 mL application of 0.3% DMBA in benzene followed by a 60 mL application of cyclohexane twice weekly for 50 weeks.

Экологическая судьба

Biological. Microbial degradation products reported include cyclohexanol (Dugan, 1972; Verschueren, 1983), 1-oxa-2-oxocycloheptane, 6-hydroxyheptanoate, 6-oxohexanoate, adipic acid, acetyl-CoA, succinyl-CoA (quoted, Verschueren, 1983), and cyclohexanone (Dugan, 1972; Keck et al., 1989).
Photolytic. The following rate constants were reported for the reaction of cyclohexane and OH radicals in the atmosphere: 5.38 x 10^-12 cm³/molecule?sec at 295 K (Greiner, 1970); 6.7 x 10^-12 cm³/molecule?sec at 300 K (Darnall et al., 1978); 6.69 x 10^-12 cm³/molecule?sec at 298 (DeMore and Bayes, 1999); 7.0 x 10^-12 cm³/molecule?sec (Atkinson et al., 1979); 7.49 x 10^-12 cm³/molecule?sec (Atkinson, 1990). A photooxidation reaction rate constant of 1.35 x 10^-16 cm³/molecule?sec was reported for the reaction of cyclohexane with NO3 in the atmosphere (Atkinson, 1991).
Chemical/Physical. The gas-phase reaction of cyclohexane with OH radicals in the presence of nitric oxide yielded cyclohexanone and cyclohexyl nitrate as the major products (Aschmann et al., 1997).
Cyclohexane will not hydrolyze because it has no hydrolyzable functional group.

Перевозки

UN1145 Cyclohexane, Hazard Class: 3; Labels: 3-Flammable liquid.

Несовместимости

May form explosive mixture with air. Contact with oxidizers, nitrogen dioxide, and oxygen can cause fire and explosion hazard. Can explode in heat when mixed with dinitrogen tetraoxide liquid.

Утилизация отходов

Dissolve or mix the material with a combustible solvent and burn in a chemical incinera- tor equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.