Re2O7 is used to convert guaiacol in alcohols at 280-320 degrees C. In ethanol, guaiacol is deoxygenated and alkylated, and the major products are phenol and alkylphenols (including ethylphenol, diethylphenol, diisopropylphenol, di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol), accounting for 97 mol% of all products after 6 hour reaction at 320 degrees C. Both catechol and phenol are the intermediates of guaiacol demethoxylation. Among the substituents, ethyl is directly provided by ethanol while isopropyl and tert-butyl are formed by the addition of methyl to ethyl step by step. In addition, Re2O7 has negligible activity for the saturation of benzene ring so it does not cause considerable over-consumption of reductant. The actual catalyst for guaiacol demethoxylation is likely a ReIV-VI species.