The black tarry material obtained during the destructive distillation of coal is called coal tar. Coal tar is a highly viscous liquid with an unpleasant odour. Actual composition of coal tar depends upon the variety of coal used, and the temperature of distillation.
Coal tar is not a single compound. It is a mixture of about 250 different compounds of carbon. Coal tar can be separated into many valuable products by fractional distillation. Coal tar is a valuable source of raw material for synthetic dyes, drugs, explosives, perfumes and many other organic compounds.