The role of Beta zeolites in the selective single o-demethylation of alkyl-syringols to alkyl-methoxycatechols, a novel polymer building block class

Abstract

Syringyl moieties, the primary phenols in hardwood, are a valuable resource for bio-based product development, though their utility is constrained without effective catalytic de/functionalization. A promising approach is the single O-demethylation (ODM) of syringyl derivatives, yielding methoxy-catechol moieties (MC)—vicinal hydroxyphenols with a methoxy group—which offer broader but underexplored applications. This study achieved selective ODM of methyl-syringol to methyl-methoxy catechol (MMC) using commercially available Beta zeolites. Unlike other solid acid or homogeneous catalysts, Beta zeolites exhibited high selectivity for MMC (>80 mol%) due to their 3D 12-membered ring pore structure, which allows for precise control over the stepwise O-demethylation of 4-methyl syringol (MSyr). Additionally, this study demonstrated, for the first time, the application of MMC in epoxy-thermosets via glycidylation, producing a high-performance resin with a glass transition temperature (Tg) of 126°C and excellent thermal resistance, with a 5% weight loss temperature (T