Many chemical reactions depend on substances that are difficult to recover and can pollute the process. This study describes a solid helper that works without a solvent, works in water, and can be used again. Acid catalysts are at the heart of many crucial industrial processes because they accelerate reaction rates at low cost, with excellent conversion and product selectivity.

Heterogeneous lanthanide, rare-earth, and transition-metal trifluoroates may be a more environment-friendly choice when used as Lewis acid catalysts in solvent-free environments. So this one-pot reaction brings four starting materials together to produce hexahydroquinoline-3-carboxamides through a new, efficient, green synthetic process.

The useful twist is that the one-pot condensation happens without a solvent, at 70 degrees Celsius, and gives higher product yield with high catalyst recovery after a simple workup. The target was to evaluate these catalysts and find the most favorable conditions for making the products in one pot from four starting materials.

The model reaction used an aromatic aldehyde, dimedone, acetoacetanilide, and ammonium acetate. The results point to the key design choice: the acid catalyst supported on silica exhibits maximum catalytic efficiency. Spreading the iron compound across silica makes the catalyst well dispersed, rather than leaving it as one concentrated mass.

With the preferred conditions in place, the catalytic system produced a family of hexahydroquinoline-3-carboxamide derivatives with excellent outcomes. The silica-supported iron trifluoroacetate was more active than the silica-supported iron trichloroacetate across the optimization measures.

The stated reason is that fluorine withdraws electronic charge more strongly than chlorine, increasing the catalyst's acidity. Compared with catalysts reported in earlier studies, the silica-supported iron compounds performed better in the amount of catalyst used, reaction time, and product yield.

That makes this route a more economically convenient and environmentally friendly alternative for making these compounds. After recovery, the catalysts showed almost consistent catalytic activity. The study describes them as reusable without a significant reduction in catalytic activity, with recovered catalysts examined after seven cycles.

The catalysts were developed as recyclable, water-compatible helpers, and their performance was assessed in making hexahydroquinoline-3-carboxamides. They retained their catalytic activity in water and organic solvents compared with conventional catalysts, while the reaction also worked without solvent at 70 degrees Celsius.

The route offers superb product yield, a short reaction time, and an easy workup procedure, making it an efficient and favourable synthetic protocol. The study finds that iron compounds spread across silica can help build a family of useful molecules quickly and with less waste, while remaining recoverable for repeated use.