Montmorillonite as an efficient catalyst in terpinyl methylether preparation from different sources

Abstract This study investigates the direct methoxylation of renewable terpenes, α -pinene and limonene, to synthesize α -terpinyl methylether using montmorillonite-based catalysts. Two types of catalyst modifications were explored: acid-treated and iron-exchanged montmorillonites. Comprehensive characterization of the materials revealed that acid treatment significantly enhanced both the acidity and catalytic activity of the clays, whereas the untreated montmorillonite remained inactive. Among the iron-modified catalysts, the sample calcined at 400 °C exhibited the highest activity (90% conversion, 69% selectivity), outperforming both non-calcined and high-temperature-calcined variants. Acid-treated montmorillonites demonstrated superior catalytic efficiency, achieving up to 70% selectivity to α -terpinyl methylether at complete conversion. Additionally, α -pinene was found to be more reactive than limonene under the tested conditions. These findings highlight the effectiveness of tailored montmorillonite catalysts in promoting selective etherification reactions. The use of earth-abundant, metal-free or minimally modified materials underscores the potential for sustainable and environmentally friendly approaches to terpene valorization in green chemistry applications.