Reaction of coal with 1,2,3,4-tetrahydroquinoline in a perfluorocarbon medium

Three very different coals show similar behaviour when heated with low concentrations of 1,2,3,4-tetrahydroquinoline (THQ : COAL = 0.2) at 250°C in a perfluorocarbon liquid. The coals all approach 33–35 % ultimate solubility (measured in pyridine) at similar rates, with little incorporation of THQ into the coal. This transformation is attributed to a low-temperature chemical reaction between THQ and coal. Appreciable coal conversion is only observed in media in which organic molecules have limited solubility, such as perfluorocarbon liquids and water. Under similar conditions, tetralin and a variety of amines other than THQ do not effect similar coal transformations. Among model compounds, consisting of various linkages connecting phenyl groups, only disulphide and ester linkages were observed to react under conditions of the coal transformation. A poly(phenyl ester)polymer, however, was found not to react. Substituents on the phenyl groups may be required to activate bonds for reaction with THQ under the conditions of this experiment.