RuO_4 is known to have a nature to attack preferentially sp^2 carbon in organic materials, therefore this reagent can be applied for structural analysis of aliphatic portions in coal. One of the most serious problems of the reaction with RuO_4 is a lack of material balance. In the present study, we tried to solve this point by analyzing extensively water-soluble and organic solvent soluble portions, and finally succeeded in attaining about 90-100% carbon recovery. In this presentation, we are to report the results of this reaction of four different rank coals (two brown and two bituminous coals).
