Synthesis And Gelation Properties Of N-long Chained Acyl Glutamic Acid And Derivatives

N-lauroyl-L-glutamic acid and its derivatives were prepared. The synthesis conditions of Schotten-Banmann condensation reaction was optimized by discussing. the influence factors of reaction, such as ratio of raw material, speed of adding, pH, a stirring power, washing, drying etc, and carrying out an orthogonal experiment. The result of orthogonal experiment showed the optimum reaction conditions, as follows: molar ratio of lauroyl chloride to glutamic acid was 1:1.6; reaction time was 5h; reaction temperature was 30℃; 60% aqueous acetone as solvent; the range of pH in the process of reaction was 9～10; pH in adjusing products was about 1; the yield was 80%.The structure of N-long chained acyl glutamic acid and derivatives were identified by IR and MS.A reversed phase high performance liquid chromatographic method for the determination of N-long chained acyl glutamic acids was developed by studying N-lauroyl-L-glutamic acid. The sample was analyzed on a reversed phase ODS column with methanol-water-acetic acid (V /V /V, 90 /5/0.5 ) as mobile phase at a flow rate of 1mL/min, temperature at 30℃, injection volume 20μL , and detected with a refractive index detector system. The average recovery were 99.3%～102.0% and relative standard deviation was 0.39%.The gelation properties and thermodynamics of N-long chained acyl glutamic acids and derivatives as gelators in different organic solvents were tested and investigated. FT-IR spectroscopy, optical micrograph and scanning electron micrograph were used to characterized the micro-structural properties of these organogelsThe result of the range of gelation in different organic fluids indicated that N-long chained acyl glutamic acids and N-lauroyl-L-glutamic acidα,γ-dibutylamide could gelate various organic fluids.The sol-gel phase transition temperatures of N-stearoyl-L-glutamic acid and N-lauroyl-L-glutamic acidα,γ-dibutylamide were obtained respectively. The detail picture was given by the investigation of the concentration dependence of sol-gel transition temperatures. TheΔH values in xylene and ethanol-water(V:V/1:1) for N-stearoyl-L-glutamic acid were 24.5 kJ·mol–1 and 56.4 kJ·mol–1 respectively. TheΔH values in counterparts for N-lauroyl-L-glutamic acidα,γ-dibutylamide were 45.0 kJ·mol–1 and 37.0 kJ·mol–1 respectively.It was found by DSC that the enthalpyΔHm of gel-sol phase transition for N-stearoyl-L-glutamic acid was 14.7 kJ·mol-1 . FT-IR data suggested that the gelators caused gelation with self-aggregation through intermolecular hydrogen bonding interaction. The distinct mincro-structures of organogels in different solvents were observed by optical micrograph.The scanning electron micrograph of a dried gel obtained from N-stearoyl-L-glutamic acid in the mixture of ethanol and water(V:V /1:1) showed the sheetlike structure.