Abstract:
Subdivided coal, oil shale or tar sands is extracted under non-thermally destructive conditions with a solvent liquid containing a compound having the general formula: ##STR1## where R, R. sub. 1, and R. sub. 2 are each hydrogen atoms, lower alkyl (C. sub. 1 -C. sub. 4) groups, or phenyl groups; provided that the compound has a decomposition temperature higher than the temperature of the extraction, and the extraction temperature is below the softening or decomposition temperature of the material being extracted.