コールタールピッチ中の窒素化合物の分析

抄録

Analytical methods have been developed for determination and characterization of the compounds containing nitrogen functional groups, found in small quantities in coal tar and pitch, without separation procedures. 1) Identification of chemical forms : The nitrogen functional groups were transformed into N-methyl (or ethyl) derivatives by the reaction with methyl or ethyl iodide, and were detected by ¹H-NMR (Nuclear Magnetic Resonance) spectroscopy. The hydrogen chemical shifts of the N-methyl and the N-methylene groups enabled to identify the nitrogen functional groups (amines, pyrroles, and pyridines). 2) Characterization of the pyridine-type compounds : N-methyl quarternary salts of the pyridines, formed by the N-methylation, were detected selectively by FABMS (Fast Atom Bombardment Mass Spectrometry) using glycerine as matrix. The pyridine-type compounds could also be detected as N-protonated pyridinium ions by FABMS using glycerine matrix containing an acid.
These methods have been applied to characterize coal tar and pitch. Pyridine-type compounds of one- to four-ring structure were found in coal tar, and those of three- to six-ring structure were found in hexane-soluble fraction of pitch.