Solventes sustentáveis para a hidroformilação

Abstract

Hydroformylation reactions are employed in industry producing aliphatic aldehydes used in the synthesis of higher value-added products. Conventional solvents used in these processes impact negatively on human health and in the environment, motivating the search for alternative forms of production, following the principles of green and sustainable chemistry. In this work, the effect of the solvent on the hydroformylation of 1-octene, styrene, diisobutylene, estragole, limonene, perillyl alcohol, α-pinene, myrtenol and 1-hexene catalyzed by a catalytic system based on Rh/PPh3 or Rh/TBPP was investigated. The solvents tested were: methoxycyclopentane (CPME), dimethyl isosorbate (DMI), cyrene™ and glyceryl triacetate (triacetin), considered sustainable in the current literature, and the biorenewable solvents: pinane, p-cymene/p-menthane mixture (2:1 v:v), solketal, dihydroeugenol and p-propylanisole. The conversions, selectivities and reaction rates were analyzed, taking as reference the reactions in toluene and texanol™ as petrochemical solvents and in anisole and propylene carbonate as sustainable solvents. In the hydroformylation of 1-octene and styrene, the solvents glyceryl triacetate and p-cymene/p-menthane had their performance equal to or better than that in toluene. Since glyceryl triacetate is classified as a highly sustainable solvent, it was used as a solvent for the hydroformylation of the other substrates. An increase in the reaction rate and a reduction in concurrent C=C isomerization reactions were observed. Triacetin has preliminarily proven to be a suitable solvent for catalyst recycling for up to 5 cycles. Through sustainability metrics (PMI and E factor), the process in triacetin has proven to be more sustainable compared to toluene. The solvents have proven to be promising alternatives for use in the hydroformylation of petrochemical and biorenewable olefins, with outstanding results for triacetin.