M(acac)n Covalently Anchored onto Amine Functionalized Silica: Highly Efficient and Recyclable Heterogeneous Catalysts for the Acetylation of Amines, Phenols and Alcohols Under Solvent-Free Conditions

In the present work, we have developed an efficient catalytic procedure for the chemo-selective acetylation of various substrates like amines, phenols and alcohols into their corresponding acetylated products using acetyl chloride in the presence of catalytic amount of metal acetylacetonates covalently anchored onto amine functionalized silica under solvent-free conditions. The catalysts were characterized by FT-IR, TGA and AAS analysis. The most active catalysts, SiO2-Co(acac)2 and SiO2-Cu(acac)2 were further characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The catalysts were found to be stable and recycled several times without significant loss of activity. Easy preparation/heterogeneous nature of catalyst, solvent-free mild reaction conditions, higher yields and versatility towards various substrates make this method a facile tool for acetylation of various functional groups.