Structural analysis of the methylated product of coal. IV. GC-MS analysis of n-hexane soluble portions.

Compound-type analyses (Z number) of n-hexane soluble portions (HS) of reductively methylated Yubari and Taiheiyo coals were studied by GC-MS.These HS were separated into 6 fractions using GPC, which were subsequently fractionized into 4-11 subfractions with liquid chromatography (Fig. 1). The true Z numbers of each molecular ion peaks were decided by high resolution mass spectra and contents of the type compounds were determined by molecular ion strength of mass chromatograms.Aliphatic hydrocarbons eluted in hexane fractions and di-, tri-, tetra-, penta- and hexacyclic aromatic hydrocarbons (Z=-16--32) in benzene-hexane fractions and oxygen-containing aromatic hydrocarbons (Z=-20--28) in methanol fractions.The contents of the type compounds contained largely in both HS were remarkably different (Table 8). Paraffins and aromatic type compounds with Z=-20 and-22 were more abundant in Yubari HS, whereas the compounds Z=-18 was more abundant in Taiheiyo HS. Naphtalene dimers were found in both HS. Numbers of alkyl side chain range from 0 to 7 and have a maximum at 3 in Yubari HS and 2 in Taiheiyo HS (Table 8).