oals are oxidized by boiling with 1NHNO3, comparatively hydrogenrich part in coal molecule is destroyed producing the humic acid in good yield, and in thisselective oxidation process a distinctive feature that oxalic acid and volatile acids are scarecely produced is noticeable.Regarding to this speciality, for the purpose to discuss the structural aspects of the part which is destroyed in this process, about thirty various structural compounds were boiled in 1NHNO3, and the compounds whose chemical behaviours fit for the above-mentioned speciality were searched .Alicyclic structure seemed most suitable.
On the other hand, humic acids prepared from bituminous coals by boiling in 1NHNO
3 and about twenty substances were oxidized with alkaline permanganate at 20°C According to the considerations aloubt chemical stoichiometry and reaction rate, no special facts indicating the selectiveness of this process were observed, excepting that at the early stage of reaction the condensed phenolic structure seemd to be oxidized:comparatively selectively; and it was followed by the conclusion that there is no reason to consider some intermediate steps in the degradation process of humic acid to benzene carboxylic acids .
After all, it was concluded that the molecule of coal consists of two distinctive structura parts;one is destroyed by boiling with 1NHNO
3 and is in alicyclic structure, the other is resist for 1NFINO3 at its boiling point and is in condensed aromatic structure .This heterogenety in chemical structure of coal molecule, however, increasees its clearness according to the advance of the coalification up to the higher rank bituminous coal .
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