Optimization of microwave-assisted esterification of succinic acid using Box-Behnken design approach.

Esters of butanedioic acid (succinic acid) are appealing renewable esters as fuel additives and solvents. In the present study, we have investigated reaction routes for the esterification of succinic acid (SA) with alcohols like methanol (MeOH), ethanol (EtOH), and 2-propanol (2-PrOH) using heterogeneous catalyst D-Hβ (moderate Bronsted acidity) in a microwave (MW)-irradiated reactor to increase yield and minimize waste generation. Using the Box-Behnken design (BBD) approach, operating parameters such as reaction time, microwave power, and catalyst dosing were optimized for SA esterification with MeOH. At optimum conditions using D-Hβ catalyst, 99% maximum conversion was achieved with 98% selectivity of dimethyl succinate (DMS). At optimum conditions, the esterification of SA with EtOH and 2-PrOH was also performed. The use of D-Hβ is economically more advantageous as it can be reused directly without any prior washing and also showed significant activity.