Synthesis, Puritition And Characteristic Comparison Of The Sucrose Fatty Acid Monoester Under Ultrasonic Irradiation

Firstly, the lauroylsucrose synthesis under ultrasonic condition was separated, after thatpurified by the thin layer chromatography (TLC) and silica gel column chromatography. Purifiedproducts were analyzed by IR, MS, HPLC and NMR. Optimum conditions for TLC wereconfirmed:4μL of the reaction mixture were applied to silica gel G plates, developed bychloroform-methanol-aceticacid-water (75:15:7:3, V/V/V/V), and then detected by spraying with10%of phosphomolybdic acid hydrate in ethanol and heated at105°C for10min. Optimumconditions for silica gel column chromatography were:3g sample dissolved in eluent wasapplied to35mm×700mm silica gel column (200-300mesh) and chloroform-methanol-aceticacid-water (75:15:7:3, V/V/V/V) was used as mobile phase. Purified products were6-O-lauroylsucrose and6’-O-lauroylsucrose.Furthermore, raffinose long-chain fatty acid esters were synthesized in dimethylsulfoxide bythe acylation of raffinose with methyl laurate under reduced pressure with ultrasound irradiation.Optimum parameters of the reaction were as follows: the reaction pressure was10KPa, thequantity of anhydrous K2CO3was12%accounted for raffinose’ mol, the molar ratio ofraffinose/methyl laurate was2:1, reaction time was2h, reaction temperature was65°C, and theyield was44.3%. Optimum conditions for TLC were confirmed:4μL of the reaction mixture wasapplied to silica gel G plates, developed by chloroform-methanol-aceticacid(V/V/V，75:25:4),and then detected by spraying with10%of phosphomolybdic acid hydrate in ethanol and heatedat105°C for10min. Optimum conditions for silica gel column chromatography were:1g sampledissolved in3mL eluent was applied to15mm×700mm silica gel column (200-300mesh), andchloroform-methanol-acetic acid was used as mobile phase. Purified products were analyzed byHPLC, IR, MS and NMR, and identified1’-O-lauroylraffinose and6’-O-lauroylraffinose. Thetwo lauroylraffinose isomerides have similar solubility in solvent and higher thermal stability.Next,1’-O-lauroylsucrose and6’-O-lauroylsucrose were formed through hydrolyzingsynthesized1’-O-lauroylraffinose and6’-O-lauroylraffinose by chemical method, respectively, inthe presence of α-galactosidase. The enzymatic hydrolysis of1’-O-lauroylraffinose and6’-O-lauroylraffinose was discussed in detail. Acetic acid-sodium acetate was chosen as thebuffer solution of the enzymatic hydrolysis reaction. Optimum conditions for the enzymatichydrolysis reaction were as follows: buffer solution pH3.8, enzymatic time48h, and enzymatictemperature37°C. Under optimal process conditions, the efficiency of α-galactosidase was ca.82.6%. Ultimately, isomers were fully compared in solubility, hydrophile-lipophile balance (HLB)values, critical micelle concentration (CMC), and thermal stability. Results showed that alllauroylsucrose isomers have similar solubility in solvent, HLB values, CMC values, and thermalstability.