From CO2 to dimethyl carbonate with dialkyldimethoxystannanes: the key role of monomeric species.

Abstract : The formation of dimethyl carbonate (DMC) from CO(2) and methanol with the dimer [n-Bu(2)Sn(OCH(3))(2)](2) was investigated by experimental kinetics in support of DFT calculations. Under the reaction conditions (357-423 K, 10-20 MPa), identical initial rates are observed with three different reacting mixtures, CO(2)/toluene, supercritical CO(2), and CO(2)/methanol, and are consistent with the formation of monomeric di-n-butyltin(iv) species. An intramolecular mechanism is, therefore, proposed with an Arrhenius activation energy amounting to 104 ± 10 kJ mol(-1) for DMC synthesis. DFT calculations on the [(CH(3))(2)Sn(OCH(3))(2)](2)/CO(2) system show that the exothermic insertion of CO(2) into the Sn-OCH(3) bond occurs by a concerted Lewis acid-base interaction involving the tin center and the oxygen atom of the methoxy ligand. The Gibbs energy diagrams highlight that, under the reaction conditions, the dimer-monomer equilibrium is significantly shifted towards monomeric species, in agreement with the experimental kinetics. Importantly, the two Sn-OCH(3) bonds are prompt to insert CO(2). These results provide new insight into the reaction mechanism and catalyst design to enhance the turnover numbers.
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Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2011, 13 (6), pp.2401-2408. 〈10.1039/c0cp02089c〉
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Soumis le : lundi 28 octobre 2013 - 14:59:19
Dernière modification le : jeudi 6 septembre 2018 - 15:12:04

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Mahboubeh Poor Kalhor, Henry Chermette, Stéphane Chambrey, Danielle Ballivet-Tkatchenko. From CO2 to dimethyl carbonate with dialkyldimethoxystannanes: the key role of monomeric species.. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2011, 13 (6), pp.2401-2408. 〈10.1039/c0cp02089c〉. 〈hal-00877433〉

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