An industrial process for making chlorobenzene (and phenol) by a gas-phase reaction between benzene vapour, hydrogen chloride, and oxygen (air) at 230°C:2C6H6+2HCl+O2 → 2H2O+2C6H5Cl The catalyst is copper(II) chloride. The chlorobenzene is mainly used for making phenol by the reaction C6H5Cl+H2O → HCl+C6H5OH This reaction proceeds at 430°C with a silicon catalyst. The process was invented by the German chemist Fritz Raschig (1863–1928).
2C6H6+2HCl+O2 → 2H2O+2C6H5Cl
C6H5Cl+H2O → HCl+C6H5OH