Synthesis of geminal diacetates (acylals) using heterogeneous H3PW12O40 supported MCM-41 molecular sieves

Mesoporous Si-MCM-41 and Al-MCM-41 molecular sieves in four Si/Al ratios 25, 50, 75 and 100 were synthesized under hydrothermal condition. 10 wt.%, 15 wt.% and 20 wt.% H3PW12O40 (PW) was supported on Si-MCM-41 and characterized using powder X-ray diffraction (XRD), FT-IR, BET and TEM techniques. Geminal diacetates were synthesized from a variety of aromatic aldehydes including those carrying electron donating or withdrawing substituents in good yields. The relatively non-toxic nature of the catalyst, its ease of handling and its easy availability makes the procedure attractive for eco-friendly organic synthesis. 20 wt.% PW/MCM-41 was found to be more active than other catalyst used and have similar activity as that of unsupported heteropoly acids (HPAs).