Avaliação do efeito de diferentes ligantes, presentes na estrutura de complexos de estanho (IV), na reação de metanólise de óleo de soja

Abstract

In this work we have investigated the catalytic activity of Sn(IV) complexes, exhibiting Lewis acid character: dimetyldineodecanoatetin, dibutyldineodecanoatetin, dioctyldineodecanoatetin, dimetyldiundec-10-enoatetin, dibutyldiundec-10-enoatetin e tributylundec-10-enoatetin. The complex nature was confirmed by infrared spectroscopy and nuclear magnetic resonance. These complexes were tested in the methanolysis of soybean oil, at different reaction conditions, in order to investigate the effect of different ligands coordinated to the metal center. Two different types of reactors have been employed on transesterification: an open glass reactor, equipped with a reflux condenser (RVCR), and a closed steel reactor (RP). The reaction products were characterized by gas chromatography. Results point out that the use of the closed steel reactor is advantageous, since higher yields are obtained in shorter reaction times. The following orders of reactivity were established, independent of temperature and the reactor used: DMTDN> DBTDN> DOTDN in the case of catalysts of the first series and DMTDU> DBTDU> TBTDU for second series. This behavior can be related to the steric effects of different ligands bearing Sn(IV). Moreover, when high temperatures are employed in alcoholysis of triglycerides, the catalysts showed higher catalytic activities. Finally, under the conditions studied, the use of the base of tin(IV) complex proved to be very promising in the methanolysis of soybean oil in order to obtain biodiesel.