Stereoselective hydrogenation of guaiacol to cis-2-methoxycyclohexanol using supported rhodium catalysts in supercritical carbon dioxide

• Published in: Catalysis today 2024-01, Vol.425, p.114356, Article 114356
• Main Authors: Yamaguchi, Aritomo, Murakami, Yuka, Yamazaki, Kiyoyuki, Shirai, Masayuki, Hiyoshi, Norihito
• Format: Article
• Language: English
• Subjects: Guaiacol; Hydrogenation; Stereoselectivity; Supercritical carbon dioxide; Supported rhodium catalyst
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2023.114356

Selective hydrogenation of lignin-derived phenolic monomer to valuable chemicals has attracted attention and investigated well; however, stereoselective hydrogenation is required for practical applications, and is still challenging. In this study, we examined the stereoselective hydrogenation of guaiacol to cis-2-methoxycyclohexanol over supported metal catalysts in several solvents at mild reaction conditions. Rh/C in supercritical CO2 gave a higher proportion of cis-2-methoxycyclohexanol in total 2-methoxycyclohexanol compared to water solvent. Finally, guaiacol could be stereoselectively hydrogenated to cis-2-methoxycyclohexanol with the yield 83.9 % (total 2-methoxycyclohexanol yield was 95.5 %) even at 313 K for 1 h using the Rh/C catalyst in supercritical CO2 (CO2 25 MPa, H2 1.5 MPa). [Display omitted] •Rh/C showed high activity for ring hydrogenation of guaiacol to 2-methoxycyclohexanol.•The reaction rate of guaiacol hydrogenation in supercritical CO2 was higher than those in other solvents.•cis-2-Methoxycyclohexanol was obtained stereoselectively in supercritical CO2.