Ethyl levulinate (EL) is an important bio-based building block obtained from a sugar platform to produce chemicals, pharmaceuticals, solvents, plasticizers, and biofuels. In this work, a taurine-based ionic liquid ([TauIm][HSO₄]) was synthesized via Debus-Radziszewski reaction to form an imidazole ring followed by acidification with sulfuric acid to obtain a highly acidic ionic liquid for cellulose conversion (Figure 1). A face-centered central composite design was carried out on ethyl levulinate production under microwave irradiation from microcrystalline cellulose to evaluate the acidity of [TauIm][HSO₄] (Figure 2). During the experiments, the taurine-based IL provided a good cellulose solubilization in ethanol followed by chemical conversion. According to the proposed design, the higher EL yields (81%) were achieved at the upper levels of all factors (temperature (A), time (B) and IL amount (C)). Experiments with non-woody lignocellulosic biomass – sugarcane bagasse and elephant grass leaves – were carried out to evaluate the potential use of [TauIm][HSO₄] in real feedstocks. Sugarcane bagasse provided 59 ±4% EL yield and elephant grass 43 ± 5% at 190 °C for 1 h applying 10 eq. of IL, which are promising results obtained from raw feedstocks. In both cases, lignin may cause an interference acting as a chemical barrier for the IL action. For elephant grass, the high extractives content may also cause interference in EL production, explaining the lower yields compared to sugarcane bagasse. These results showed that [TauIm][HSO₄] had a great potential for biomass conversion without any pretreatment. The use of this IL to other feedstocks will also be presented.

Camila Rezende

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