Catálise na valorização de produtos naturais via processo one-pot: síntese de nopol e seu acetado a partir do β-pineno e acetilação/cloração do β-Citronelol.

Abstract

Aiming to add value to natural products, several catalytic one-pot processes were developed by performing various chemical reactions in the same reactor via a single manipulation procedure. β-Citronelol and β-pinene were used as the substrates in these processes. Chlorinated and chlorinated/acetylated derivatives were obtained from β-Citronelol. β-Pinene was used to synthesize nopol and nopyl acetate. Due to pleasant organoleptic characteristics, nopol and nopyl acetate are widely desired by industry as flavor ingredients in cosmetic and fragrances products. The compounds derived from β-Citronenol can be used as intermediates in organic synthesis, e.g., for the production of aldehydes. Following the green chemistry principles, catalysts and green solvents were employed in these reactions. In the chlorination processes, the Keggin serie heteropoly acid supported in silica (20% H3PW12O40/SiO2) was employed as the catalyst. The use of these compounds offers great advantages for the process sustainability due to their low toxicity and non-corrosive properties. In certain reaction media, heteropoly acids can be used as heterogeneous catalysts which makes easy their recovering and reusing. In the synthesis of nopol and nopyl acetate the tin containing materials, Sn/SiO2 and Sn/MCM-41, were used as the catalysts. Sn/MCM-41 demonstrated better catalytic performance as compared to Sn/SiO2. Dimethylcarbonate, diethylcarbonate, propelyne carbonate, anisole, methylisobuthylketone and methylethylketone were used as solvents in these reactions, being all considered as environmentally friendly green solvents. The chlorinated and chlorinated/acetylated derivatives of β-Citronelol were obtained in 91 and 82% yields, respectively, in diethylcarbonate or dimethylcarbonate solutions. Nopol was obtained in 94% yield in dimethylcarbonate, whereas nopyl acetate in 85% yield in propylene carbonate.