Preparation of 4,4-bis(5-methylthiophen-2-yl)pentanoic acid from biomass-based functional molecules using solid acid catalysts

For the first time, the successful synthesis of 4,4-bis(5-methylthiophen-2-yl)pentanoic acid (bisthiophenic acid-methyl; BTA-M) and its alkyl esters (BTAE-M) from levulinic acid (LA) and its esters with 2-Methylthiophene (2-Met) has been achieved, utilizing solid acid catalysts (Amberlyst-15 and Indion-190). Notably, Indion-190, a cost-effective catalyst, demonstrated the formation of BTA-M and bisthiophenic methyl ester-methyl (BTME-M) with 96–98% selectivities and 99% conversion of LA and methyl levulinate under optimized, solvent-free reaction conditions. The recyclability of Indion-190 has been showcased, maintaining good recyclability for the preparation of BTA-M and BTME-M over three reaction cycles, with a slight decrease in the conversion of reactants.