engleski

Solid acid catalyzed aldol dimerization of levulinic acid for the preparation of C10 renewable fuel and chemical feedstocks

The acid catalyzed condensation of levulinic acid was studied using a series of solid acid catalysts: Amberlyst-15, SiO2-SO3H, Dowex50WX8, Carbon-SO3H, TiO2-SO3H, Al2O3-SO3H, H3PW12O40, and Nb2O5.H2O under neat conditions at 110– 130 °C. The major dimerization product was identified as tetrahydro-2-methyl-5, γ-dioxo-2- furanpentanoic acid. In addition, four minor products were identified as diastereomeric pairs of 3-(2-methyl-5-oxo-tetrahydrofuran-2- yl)-4-oxopentanoic acid and 3-acetyl-2-methyl- tetrahydro-5-oxo-2-furanpropanoic acid by spectroscopic and computational methods. A mechanism is proposed to explain the formation of five dimerization products where the major product is formed via the aldol condensation of C5 enol form of levulinic acid and four minor products are arising from the aldol condensations C3 enol form of levulinic acid. The highest total yield 56% was obtained with the use SiO2-SO3H as the solid acid catalyst and the reminder of the mass balance was unreacted levulinic acid. The SiO2-SO3H catalyst could be recycled four times with some loss in catalytic activity.

Levulinic acid ; Aldol condensation ; Solid acid ; Silica - sulfuric acid ; Dimerization

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