Synthesis of oxamate and urea by oxidative single and double carbonylation of amines using immobilized palladium metal-containing ionic liquid@SBA-15

• An efficient method for the synthesis of oxamate and urea by oxidative carbonylation reaction.
• Base, co-catalyst, dehydrating agent and ligand-free system for the oxamate synthesis.
• Heterogeneous and recyclable catalytic system.

A promising route for the synthesis of oxamate and urea by oxidative carbonylation of amine is described using immobilized palladium metal-containing ionic liquid onto mesoporous silica (ImmPd-IL-@SBA-15). Adequate adjustments of the different reaction parameters such as solvent, additives temperature, and substrate to achieve optimal catalyst performance were made using ImmPd-IL@SBA-15 as a catalytic system. The ImmPd-IL@SBA-15 catalyst along with NaI promoter showed high selectivity to the desired products over several amine compounds such as aliphatic, aromatic, allylic etc. The secondary amines selectively cross double carbonylated with alcohol to give the oxamate derivatives and the primary amines provided the urea as a product by the single carbonylation. The fresh and recycled catalyst was characterized using XPS and TEM-EDX analysis. The carbonylation route proposed here eliminates the need for corrosive, moisture-sensitive, thermally unstable monoesters of oxalyl chlorides and provides a cleaner synthetic route for the synthesis of oxamates using ImmPd-IL@SBA-15 as a heterogeneous and reusable catalyst. Notably reaction does not require air/moisture sensitive phosphine ligands, co-catalyst and dehydrating agent with an additional advantage of palladium catalyst recovery and reuse for up to six consecutive cycles without loss in activity and selectivity.

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