Efficient Alcoholysis of Saponins from Dioscorea zingiberensis by Solid Acids Derived from Diethylenetriamine

Low-molecular weight solid acid, [(DETA-(SO 3 H) 2 ], was synthesized and fully characterized by FTIR, XRD, TGA, XPS, 1 H-NMR and elemental analysis. The prepared solid acid exhibited high strong acid density (7.6 mmol H + /g), much higher than most of other solid acids. The solid acid was used for the extraction of diosgenin from the saponins in Dioscorea zingiberensis C. H. Wright. Diosgenin is a very medical intermediate for the synthesis of various kinds of steroidal drugs. To improve the diosgenin yield, the optimal conditions of the extraction reaction were investigated by single-factor experiments. Under the optimized conditions, the diosgenin yield catalyzed by the solid acid was much higher than those obtained by the catalysis of other solid acids or conventional sulfuric acid. Importantly, no waste liquid was discharged in the approach as the reaction medium can be recycled. The alcoholysis approach for the production of diosgenin has a great potential application in the industry. Graphical Abstract A novel low-molecular weight solid acid was synthesized and fully characterized. The solid acid showed excellent catalytic activity for the catalytic alcoholysis of saponins from D. zingiberensis C. H. Wright (DZW), the catalyst can be recycled and the whole extraction process is green and efficient.