A DFT Study of the Conversion of CO2 in Dimethylcarbonate Catalyzed by Sn(IV) Alkoxides

• Autor(a) principal: Renata,C. de Souto
• Data de Publicação: 2014
• Outros Autores: Rosenbach Jr.,Nilton, Mota,Claudio J. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532014001202322
• topic: CO2; dimethylcarbonate; tin alkoxides; DFT

Density functional theory (DFT) calculations of intermediates and transition states of the reaction between CO2 and methanol over different R2Sn(OCH3)2 catalysts (R = alkyl, phenyl and halogens) were carried out. The interaction of the CO2 molecule with the tin catalyst was controlled by the entropic term, being disfavored at room temperature and atmospheric pressure. On the other hand, the insertion of the CO2 molecule into the Sn–OCH3 bond is thermodynamic favorable for all the catalysts studied. The computed free-energy of activation varied with the nature of the substituent R. Phenyl groups exhibit the smallest barrier, whereas halogen atoms the highest. Alkyl groups present intermediate barriers. The results are in agreement with recent experimental results that indicated a higher turnover number (TON) for dimethylcarbonate (DMC) formation when Ph2SnO was used as catalyst. The whole mechanistic scheme was then computed for phenyl and methyl as substituents, considering a dimer tin species.