Highly efficient acetalization and ketalization catalyzed by nano-kaolin/BF3/Fe3O4 under solvent-free condition

The protection of carbonyl groups plays an important role in multi-step organic synthesis of compounds with multiple functional groups. Cyclic acetals and ketals are the most well-established and frequently used protective strategies for the carbonyl groups.1 In addition, many acetals and ketals have wide applications in industrial manufacturing such as cosmetics, foods and fragrances, etc.2 The most general method for the synthesis of acetals and ketals is the reaction of carbonyl compounds with an alcohol or diol. Traditionally, acidic catalysts like protic acid, Lewis acids, and heteropoly acids3 were used to synthesize acetals or ketals. However, those methods suffered from several drawbacks such as corrosion, tedious work-up, environmental pollution and non-recoverability of catalysts. To solve these problems, a variety of solid acids, which were prepared by immobilization of acidic catalysts have been investigated.4 Recently, transition metal complexes have been used to catalyze the acetalization and ketalization of carbonyl compounds.5In this study, we report our results for the acetalization and ketalization of carbonyl compounds with diols under solvent-free conditions in the presence of nano-kaolin/BF3/Fe3O4 as a magnetic catalyst (Fig.1). The advantages of this study involve in use of solvent-free condition, an easy experimental work-up system, rapidity, recyclable catalyst and green process.

کلیدواژه ها:

Acetalization ، Ketalization ، Nano-kaolin/BF3/Fe3O4 ، Solvent free.