Catalytic Performance of Immobilized Sulfuric Acid on Silica Gel for <i>N</i>-Formylation of Amines with Triethyl Orthoformate

Abstract

In the search for convenient, green, and practical catalytic methods for the current interest in organic synthesis, a simple, green, and highly efficient protocol for N-formylation of various amines was carried out in the presence of immobilized sulfuric acid on silica gel (H2SO4–SiO2). All reactions were performed in refluxing triethyl orthoformate (65 °C). The product formamides were obtained with high-to-excellent yields within 4 min to 2 h. The current approach is advantageous, due to its short reaction time and high yields. The catalyst is recyclable with no significant loss in catalytic efficiency.

Keywords

• <i>N</i>-formylation
• amines
• immobilized sulfuric acid
• silica gel
• triethyl orthoformate