A Comparative study of catalytic synthesis of psuedoionone from citral

Abstract:

Lemongrass (cymbogopon citarus) essential oil, renowned for its high citral content (geranial and neral isomers), has emerged as a sustainable renewable feedstock for pseudoionone synthesis through the classic aldol condensation with acetone. Traditional extraction methods such as hydrodistillation and steam‑distillation from fresh or dried lemongrass leaves routinely yield citral‑rich oils (>70–80% citral), as verified by gas chromatography and physicochemical profiling across numerous studies. The subsequent aldol condensation of citral with acetone has historically relied on homogeneous sodium hydroxide (NaOH) catalysis, which excels under mild conditions (20–55 °C, short reaction times) and delivers high pseudoionone yields. However, this approach generates substantial alkaline wastewater necessitating neutralization, posing environmental challenges. In response, heterogeneous magnesium oxide (MgO) catalysts have gained attention as recyclable solid bases, offering facile filtration, reduced waste, and comparable performance. Comparative evaluations reveal MgO to provide equivalent citral conversions and pseudoionone yields with superior selectivity and minimal by‑product formation, aligning with green chemistry principles. This review underscores the integrated potential of lemongrass citral extraction coupled with NaOH and MgO‑catalyzed aldol condensations, paving the way for efficient, waste‑conscious production of pseudoionone a vital fragrance precursor.