Catalytic Performance of Immobilized Sulfuric Acid on Silica Gel for N -Formylation of Amines with Triethyl Orthoformate.

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 (H 2 SO 4 -SiO 2 ). 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.