Unambiguous Evidence for the Occurrence of Pentamethylphenol in Lignite Methanolysate

Lignite methanolysis is an effective method to investigate the lignite structure and obtain valuable chemicals from lignite. In this paper, pentamethylphenol was first isolated as a nearly pure compound from Shengli lignite methanolysate by the basification–acidification process, column chromatography, and recrystallization. Its structure was unambiguously identified with mass spectrometry, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Large quantities of pentamethylphenol detected in methanolysate indicate that methylation is one of primary reactions during low-rank coal methanolysis.