Use and Manufacturing

1 Chemical Reactivity

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.

2 Environmental Fate

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; Kecket al., 1989). Photolytic. The following rate constants were reported for the reaction of cyclohexane and OHradicals in the atmosphere: 5.38 x 10-12 cm3/molecule?sec at 295 K (Greiner, 1970); 6.7 x 10-12cm3/molecule?sec at 300 K (Darnall et al., 1978); 6.69 x 10-12 cm3/molecule?sec at 298 (DeMoreand Bayes, 1999); 7.0 x 10-12 cm3/molecule?sec (Atkinson et al., 1979); 7.49 x 10-12cm3/molecule?sec (Atkinson, 1990). A photooxidation reaction rate constant of 1.35 x 10-16cm3/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 ofnitric 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.

3 Potential ExposureCyclohexane is used as a chemicalintermediate; as a solvent for fats, oils, waxes, resins, cer-tain synthetic rubbers; and as an extractant of essential oilsin the perfume industry

4 Produe MethodCyclohexane is fractionated from crude oil and may bereleased wherever petroleum products are refined, stored,and used. Another large source of general release is inexhaust gases from motor vehicles. It is prepared syntheticallyfrom benzene, by hydrocracking of cyclopentane,or from toluene by simultaneous dealkylation and doublebond hydrogenation.

5 Purification MethodsIt is best to purify it by washing with conc H2SO4 until the washings are colourless, followed by water, aqueous Na2CO3 or 5% NaOH, and again water until neutral. It is then dried with P2O5, Linde type 4A molecular sieves, CaCl2, or MgSO4 then Na and distilled. Cyclohexane has been refluxed with, and distilled from Na, CaH2, LiAlH4 (which also removes peroxides), sodium/potassium alloy, or P2O5. Traces of *benzene can be removed by passage through a column of silica gel that has been freshly heated: this gives material suitable for ultraviolet and infrared spectroscopy. If there is much *benzene in the cyclohexane, most of it can be removed by a preliminary treatment with nitrating acid (a cold mixture of 30mL conc HNO3 and 70mL of conc H2SO4) which converts *benzene into nitrobenzene. The impure cyclohexane and the nitrating acid are placed in an ice bath and stirred vigorously for 15minutes, after which the mixture is allowed to warm to 25o during 1hour. The cyclohexane is decanted, washed several times with 25% NaOH, then water, dried with CaCl2, and distilled from sodium. Carbonyl-containing impurities can be removed as described for chloroform. Other purification procedures include passage through columns of activated alumina and repeated crystallisation by partial freezing. Small quantities may be purified by chromatography on a Dowex 710-Chromosorb W gas-liquid chromatographic column. Flammable liquid. [Sabatier Ind Eng Chem 18 1005 1926, Schefland & Jacobs The Handbook of Organic Solvents (Van Nostrand) p592 1953, Beilstein 5 IV 27.] Rapid purification: Distil, discarding the forerun. Stand distillate over Grade I alumina (5% w/v) or 4A molecular sieves.