Synthesis And Properties Of Amino Acid Glucose Easter Surfactants

The glucose-based surfactant is typical kind of non-ionic surfactant due to it’s special hydrophilic structure of many hydroxyl groups.Glucose easter has many advantages:renewable,low toxicity,high surfactivity and good biodegradability,so it has a wide range of application prospects and value in food,medicine and daily chemicals.In this dissertation,a series of amino acid glucose esters were synthesized,using a-D-methylglucoside,amino acid and fatty acyl chloride as raw materials.The hydroxyl groups of glucose were protected first and the N-acyl amino acids were prepared by Schotten-Baumann condensation reaction.Then 6-0-(N-acyl amino acid)-a-D-methyl glucose esters were synthesized by Steglich esterification and hydrogenolysis debenzylation.On the basis of reported references,the reaction conditions were improved and optimized.The structures of products were confirmed by 1H NMR and ESI-MS.The hydrophilic lipophilic equilibrium value(HLB)of glucose esters was calculated.The results showed that the HLB value of glucose esters 9a-9d decreased with the increase of acyl carbon chain length and the enhancement of the hydrophobicity of the amino acid group.In order to evaluate the surface activity and adsorption behavior,the surface tension of glucose esters aqueous solutions were measured at different temperatures.Several surface activity parameters could be calculated from the γ-logc plots.The results showed that cmc decreased,but πcmc,pC20 and cmc/C20 increased with the lengthening of hydrophobic chain.The adsorption of glucose esters in aqueous solution was positive.With the increase of chain length and the enhancement of hydrophobic amino acid group,Amin increased and Γmax decreased.The thermodynamic parameters of micellization,such as the standard Gibbs energy change(AGmθ),the standard enthalpy change(AHmθ)and the standard entropy change(ASmθ),were investigated at different temperatures.The negative values ofΔGmθ and Δmθ indicated that the micellization process of glucose esters in the aqueous solution was spontaneous and exothermic.The ΔSmθ values were positive in all cases and the values of TΔSmθ were larger than that of |ΔHmθ|.ΔSmθ was dominant in the negative value of ΔGmθ,implying that the micellization for glucose esters was entropy-driven.Several amino acid glucose esters were synthesized in this dissertation,which have a wide range of HLB values and excellent surface properties.They have bright prospects for potential development and application.