Abstract
Petroleum ether insoluble and chloroform soluble parts (γ2 fractions) of pyridine extracts of Australian Moura and Chinese Tatung coals were separated into 6 parts by solvent extractions and liquid chromatography, respectively. These parts were analyzed by 1H-, quantitative 13C-NMR and IR spectrometry.
A linear relationship exists between the ratio of optical densities of 1, 600 to 2, 920 cm-1 bands in the IR spectrum, D1600/D2920, and the ratio of aromatic carbon atoms to alkyl hydrogen atoms in the average molecular structural parameters calculated from the 1H-and 13C-NMR spectra, *Ca/*Hal. Further, it has been found that this relationship applies in γ2 fractions of Japanese coals (Taiheiyo, Akabira, Yubari and Miike) and hydrogenated products of γ2 fraction of Nakayama lignite. Assuming that H/C molar ratio of alkyl groups is 2, the estimated values of aromaticities (fa) in original coals that are only slightly soluble in solvents can be calculated from the D1600/D2920 values and this linear relationship.These estimated aromaticities in the original coals agree fairly well with the values obtained by the other methods.
