Lignin oil methyl ether (LOME) is a bio-derived solvent obtained from lignin by pyrolysis, methylation, and rectification. It performs well as an alternative polar aprotic solvent for organic reactions such as the Menschutkin synthesis of quaternary amines. Methylation of lignin pyrolysis oil was achieved using dimethylcarbonate under mild reaction conditions. The resulting methylated oil was subjected to supercritical fluid rectification in supercritical CO₂, yielding LOME (90 wt% of eight identified veratroles and anisoles) which can be directly used as a bio-derived aprotic solvent.