ABSTRACT
Most chlorobenzene is produced from benzene by chlorination in the vapour or liquid phase. Monochlorobenzene, ortho-dichlorobenzene and para-dichlorobenzene are formed during the process, the proportions of each depending on the ratio of raw materials, process conditions and catalyst used. Most monochlorobenzene is produced by the continuous chlorination of benzene in the liquid phase. The chlorobenzene layer or liquid phase is fractionated, and chlorobenzene is isolated from the dichlorobenzenes. Chlorobenzene can be produced by the reaction of benzene with hydrogen chloride in the presence of air. About 6% of dichlorobenzenes are produced as by-products. The major outlet for monochlorobenzene, which consumes around 65% of total demand, is for nitrobenzene production. The other market for monochlorobenzene–phenol manufacture–has declined due to its replacement by cumene. Chlorobenzene is moderately toxic by inhalation as well as being absorbed by the skin. Chlorobenzene is stable to air, light and moisture at room temperature.
