Collect. Czech. Chem. Commun. 1982, 47, 843-852

Structural units of maltenes and asphaltenes from hydrogenation of coal

Ivo Lang

Institute of Geology and Geotechnology, Czechoslovak Academy of Sciences, 182 09 Prague 8


The calculation of the unit structure weight (USW) from NMR data is discussed. A comparison with the average molecular weight (Mr) values from vapour phase osmometry and mass spectrometry measurements showed that for the coal maltenes investigated (the fraction from the coal hydrogenation product soluble in pentane), USW can be looked upon as a rapid approximation of Mr. For asphaltenes, the calculation of USW is to a high extent dependent upon the assumed arrangement of the aromatic system. For an approximation of Mr of the asphaltenes studied, the most satisfactory was the calculation of USW from parameters of the Williams method assuming the occurrence of a peri-cata-condensed system. The USW of coal hydrogenation products calculated from NMR (1H and 13C) spectra should not be attributed the physical meaning of their smallest building units.