Hidroformilação/acetalização de substratos biorrenováveis com glicerol: potenciais aditivos para o óleo diesel

Abstract

The great challenge of our century is the transition from fossil-based to renewable energy sources. To achieve this goal, various solutions have been implemented to replace the use of oil. However, its complete replacement is still a long way off. To achieve this, it is essential to reduce oil consumption and minimize the impacts caused by its use. This work resulted in the development of catalytic systems to promote the hydroformylation/acetalization of terpenes with glycerol for synthesizing acetals, which can be used as additives for diesel oil. In the literature, it is described that using the acetals in diesel oil increases the performance of the fuel and reduces the emission of particles which are pollutants for the environment. In addition, using glycerol as a reagent for the hydroformylation/acetalization reactions of terpenes contributes to the valorization of this waste from the transesterification of vegetable oils. The tandem hydroformylation/acetalization process of terpenes with glycerol was carried out using the rhodium catalytic precursor [Rh(acac)(CO)2] together with the pyridinium p-toluenesulfonate (PPTS), as acid co-catalyst. Limonene was used as a model substrate in hydroformylation/acetalization where the effects of the nature of the phosphorus auxiliary ligand, the P/Rh ratio, temperature, pressure, solvent, the amount of the acid co-catalyst, and the amounts of glycerol were evaluated. The best conditions found were: dimethyl isosorbide (DMI) as a eco-friendly solvent, temperature of 100 °C, pressure of 40 atm (H2/CO), and triphenylphosphine as the phosphorus auxiliary ligand. Subsequently, with the reaction conditions optimized, the glycerol hydroformylation/acetalization process was applied to other renewable substrates such as estragole, anethole, β-pinene, camphene, carvone, and perillyl alcohol, resulting in corresponding acetals with a selectivity of over 88%.