Preparation of β-mercaptopropionic acid from H2S catalyzed by novel ionic liquids

Four types of novel hydrophilic ionic liquids (ILs) were synthesized by one step method using carboxyethiosuccinic acid (CETSA) as anion and 1,5-diazabicyclo[4.3.0]-5-nonene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 3-diethylamylpropylamine (DEAPA) and 1,1,3,3-tetramethylguanidine (TMG) as cation, respectively, and characterized by 1HNMR, 13CNMR, TG, MS and FTIR. The catalytic performance of ILs on the synthesis of β-mercaptopropionic acid from acrylic acid and in-situ synthesized H2S was investigated. Under the optimized hydrothermal reaction conditions of tetrahydrofuran 35.00 g, acrylic acid 2.16 g (0.03 mol), in-situ synthesized sufficient H2S to replace the traditional gas cylinder, catalyst 3.0 mmol, reaction temperature 90 ℃, and reaction time 4.5 h, ionic liquid 1,5-diazabicyclo[4.3.0]-5-nonene carboxyethyl thioglycoate ([DBNH]CETSA) showed the best catalytic effect, with an acrylic acid conversion rate of 100% and a product selectivity of 90.57%. The conversion rate of acrylic acid still maintained at 98.97% after [DBNH]CETSA was recycled 7 times, indicating good stability and high activity of the ionic liquid. © 2023 Fine Chemicals. All rights reserved.