Crude coal tar

What is crude coal tar

Coal tar is a complex hydrocarbon mixture produced by thermal destruction (pyrolysis) of coal, typically a dark viscous liquid or semisolid with a smoky or naphthenic odor.

Composition of coal tar

The composition of coal tar will be influenced by the process used for pyrolytic distillation as well as by the original composition of the coal; however all coal tars will be comprised of a variable mixture of organic compounds including benzene, toluene, xylenes, cumenes, coumarone, indene, benzofuran, naphthalene, acenaphthene, methylnaphthalenes, fluorine, phenol, cresols, pyridine, picolines, phenanthracene, carbazole, quinolines, fluoranthene, and pyrene.

Distillation

Coal tar creosotes and coal tar distillates, oily liquids generally lighter in color and of lower viscosity than coal tar, are fractions produced by additional distillation of crude coal tar. Coal tar pitch is a highly viscous dark semisolid byproduct of coal pyrolysis. Coal tar volatiles are the vapors produced from heated coal tar or coal tar pitch, containing lower molecular weight (smaller ring number) polycyclic aromatic hydrocarbons (PAHs).

Safety and healthy

It is noteworthy as one of the first – if not the first – chemical substances documented to cause cancer through occupational exposures. In the eighteenth century, Sir Percival Pott, a British surgeon, noticed a higher incidence of cancers in chimney sweeps chronically exposed to soot and coal tar.

He then demonstrated excess cancers occurring in laboratory animals when coal tar is applied to the ears and skin. In the early twentieth century, polycyclic aromatic compounds isolated from coal tar were identified as chemical carcinogens

Analysis and data sheet

Specification of crude coal tar

MSDS of crude coal tar