Processos catalíticos one-pot em condições de hidroformilação para aplicação na química fina

Abstract

In this work, tandem catalytic processes were used, such as hydroaminomethylation (HAM) and hydroformylation/hydrogenation/acetoxylation, for the synthesis of new compounds, with potential application by the fine chemistry industry. A (HAM) is a catalytic process that allows synthesizing amines from olefins and is perfectly aligned with the precepts of the green chemistry. Therefore, HAM was applied to hydroxyolefins: isoprenol, linalool, nerolidol and isopulegol, and employing 4-methylpiperidine, morpholine and 1,2,3,4-tetrahydroisoquinoline as counterparts. Thus, several new and structurally complex amines were prepared from biorenewable and low-cost substrates, opening a path to explore this diversity of substances in terms of biological activity. The processes were catalyzed by rhodium complexes and optimized by the variation of the main parameters, such as catalytic/ligand precursor ratio, temperature, nature of the ligand and CO/H2 pressure. The unpromoted rhodium system leaded mostly to aminoalcohols, while certain rhodium systems promoted by phosphorus ligands provide amines containing a tetrahydropyran or a tetrahydrofuran moiety in moderate to high yields. Next, the hydroformylation/hydrogenation/acetoxylation reaction was used for the synthesis of new acetates from eugenol, isoeugenol, 2-allylphenol and 2-allyl-6-methylphenol. This process allowed the valorization of the biorenewable raw material in a sustainable way, often being able to decrease or eliminate the allergenic activity of certain substrates, which are commonly used as fragrance ingredients. The process was carried out in two stages, both of which were happening in the same reactor without the separation of intermediate products (one pot process). In the acetoxylation stage with alcohol and acetic anhydride, the organocatalyst DMAP (4-dimethylaminopyridine) was used. Acetic anhydride should be added after the steps of hydroformylation of olefin and hydrogenation of the aldehyde, because the presence of this reagent in the initial phase of the reaction impairs the selectivity of the process due to its interaction with aldehyde under the conditions used (150 ºC), resulting in the formation of undesirable products.