Polymers from biomass: one pot two-step synthesis of furilydenepropanenitrile derivatives with MIL-100(Fe) catalyst†
Furilydenepropanenitrile derivatives, which are useful as monomers, have been obtained in high yields by coupling the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) and the Knoevenagel condensation of DFF with methylene active compounds in a one pot process. The oxidation step was studied using an Fe containing metal–organic framework (MIL-100(Fe), and Fe(BTC)), a Cu containing MOF (Cu3(BTC)2), an Fe exchanged HY zeolite and homogeneous Fe salts in the presence of 2,2,6,6-tetramethylpiperidine-1-oxide (TEMPO) as a cocatalyst, NaNO2 as an additive and oxygen as the terminal oxidant. The results showed that the synthesized MIL-100(Fe) post treated with NH4F was the most active catalyst achieving 100% HMF conversion with 100% selectivity to DFF and can be reused with good success. Additionally, the catalytic system has been applied to the oxidation of different primary and secondary alcohols to aldehydes and ketones under mild reaction conditions with good success. The second step, the Knoevenagel condensation of the obtained DFF with malononitrile or ethyl cyanoacetate, was performed taking advantage of the basicity of the reaction medium.