Comparative Catalytic Performance of Silica-HNO3 and Silica-HCl for the Synthesis of Acylals from Aromatic Aldehydes

Abstract

Acylal is one of the most effective protecting groups for carbonyl functionality in organic synthesis. In this work an attempt was made for the first time to compare the performance of silica-HNO3 and silica-HCl as heterogeneous catalysts in the formation of acylals from aromatic aldehydes. Thus the silica-acid mixtures were prepared by mixing the column chromatographic grade silica gel with concentrated HNO3 and concentrated HCl to obtain free flowing powders. These powders at different ratios were used to investigate the formation of acylal from 3-nitrobenzaldehyde as a model reaction under different operating parameters. Subsequently, the optimum condition was applied in the conversion of some substituted aromatic aldehydes to their corresponding acylals. It was found that the two catalytic systems displayed almost similar catalytic performance affording the highest yield of the acylal at 83%.

Keywords

• Acylal
• Silica
• Brӧnsted acid
• Aromatic aldehyde

References

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