ON THE NITROGEN CONTAINING CONSTITUENTS OF COAL-TAR PITCH

Experimental evidence for a statistical distribution of the nitrogen present in coal-tar pitch among pitch constituents is presented. It is shown that the concentration of basic nitrogen compounds in pitch fractions increases with increasing molecular weight of the fractions. The general suggestion is derived that the high-molecular weight portion of coal-tar pitch is probably not predominantly a mixture of polycyclic aromatic hydrocarbons but rather a mixture of heterocyclic systems. Ion exchange chromatography, charge-transfer fractionation using picric acid as the complexing agent as well as precipitation of hydrochlorides with gaseous HCl have been used for isolation of basic pitch constituents.