Effective Synthesis of a Biodiesel Precursor from Furan Derivatives at Room Temperature with NaHSO4 as a Recyclable Catalyst

Synthesis of a biodiesel precursor from biobased materials usually needs harsh reaction conditions such as high temperature, long time, and precious catalysts. In this article, a mild pathway was provided to directly synthesize biodiesel precursor bis(furan-2-yl)methane derivatives (BFMs) with industrial salt NaHSO4 as a recyclable heterogeneous catalyst at room temperature. Over 99% yield of bis(5-methylfuran-2-yl)methane (BMFM) was obtained after 10 min reaction with 5-methylfurfuryl alcohol and 2-methylfuran (2-MF) as the substrates. Moreover, the addition of 2-MF in this work could effectively increase the BMFM yield and restrain the side reactions; then the proposed mechanism was also put forward according to the detailed mechanistic studies. In this condensation reaction, the electron donor substitute and conjugation structure on the furan ring is essential, and the crystalline water of the catalyst also promoted the catalytic efficiency obviously. Overall, this work provides a budget and practical approach for biodiesel production from biobased materials, which exhibit the potential for industrial application.