Sulphuric acid immobilized on silica gel (H2SO4-SiO2) as an eco-friendly catalyst for transamidation

A novel method of transamidation of carboxamides with amines by using catalytic amounts of H2SO4-SiO2 has been developed under solvent free conditions. The transamidation is compatible with a wide range of aromatic, heteroaromatic, aliphatic, cyclic/acyclic primary or secondary amines. The metal/solvent-free conditions represent a significant improvement over other existing methods as the reaction can be performed in open air conditions and no column purification is required. The versatility of this methodology was further demonstrated by synthesizing the commercially available drug procainamide.