Triacetin as a Sustainable Solvent for Hydroformylation

Hydroformylation (oxo process) is responsible for the world production of ca. 10 million tons of chemicals per year, employing catalytic systems based on Rh or Co in solution; therefore, the solvent plays a central role in the sustainability of these processes. We compared the performance of solvents regarded as sustainable (cyclopentyl methyl ether─CPME, dimethyl isosorbide─DMI, dihydrolevoglucosenone─Cyrene, anisole, and glycerin triacetate─triacetin) with toluene, a widely used solvent for this reaction. Employing representative catalytic systems based on Rh and substrates of petrochemical source (1-octene, styrene, and diisobutylene), triacetin stood out as a promising alternative to toluene: not only the reaction rates were higher but also the concurrent carbon–carbon double bond isomerization was reduced. Triacetin was particularly useful in the hydroformylation of more challenging renewable substrates (estragole, limonene, perillyl alcohol, α-pinene, and myrtenol), leading to higher reaction rates and better yields for the desired aldehydes as compared to toluene. Triacetin also proved to be a suitable solvent to keep the catalyst active in solution after product distillation, allowing for direct catalyst recycling.