(n-Bu2Sn)2O(CO3): An active, robust and recyclable organotin(IV) for the direct synthesis of linear organic carbonates from carbon dioxide and alcohols

Organotin(IV) compounds are known to promote the direct synthesis of organic carbonates from carbon dioxide and alcohols. In the past, structural studies have highlighted that the carbonato moiety is a recurring ligand of tin species collected during CO2 pressurized reactions. In a mimetic approach and in order to achieve an available and recyclable precursor, the title compound (n-Bu2Sn)(2)O(CO3) (1) was prepared in a single step by reacting commercial di-n-butyltin dichloride with an aqueous solution of sodium carbonate. Compound 1 was characterized using infrared spectroscopy and thermogravimetric and elemental analyses. Multinuclear NMR investigations in solution were also conducted. Compound 1 was then evaluated for the direct carbonation of alcohols (methanol, ethanol, n-butanol and isopropanol) under CO2 pressure. Recycling experiments were performed showing the efficient reuse of 1 without loss of activity. Furthermore, the infrared fingerprint of 1 was preserved even after several runs demonstrating a good stability. The effects of pressure and of reaction time on dimethyl carbonate formation were also studied.