| The citrate monoesters, which were synthesized by citric acid anhydride and fatty alcohols of different carbon chain were carried out in this paper. Four reaction systems were studied: a, Citric acid reacted with acetic anhydride;b, Citric acid anhydride reacted with decyl alcohol;c, Citric acid anhydride reacted with lauryl alcohol;d, Citric acid anhydride reacted with tetradecyl alcohol. The effects of reaction factors on the yields of citric acid anhydride and the esterifiction conversion percentage of citrate monoesters were discussed in every reaction system. The structures of citric acid anhydride and citrate monoesters were characterized by Elemental Analysis, Infrared Spectrum and Electrospray Ionization-Mass Spectrometry (ESI-MS). The surface tension and critical micelle concentration (c.m.c) of water solution of citrate monoesters were measured by Maximum Bubble Pressure Method;the properties of the products such as foaming power, dispersing power and emulsion ability were also detected.It showed: The optimum condition of synthesizing citric acid anhydride was: reaction time 18h, reaction temperature 37℃, molar ratio of materials(citric acid/acetic anhydride)1:1.8, molar ratio of solvent(citric acid/acetic acid)1:2, the yield of citric acid anhydride in this reaction condition84.7%. The structure of citric acid anhydride was asymmetrical five-number ring. The optimum condition of preparing citrate monoesters was: molar ratio(citric acid anhydride/fatty alcohol)l:1.2, reaction time 2.5 to 3 hours, reaction temperature 80 to 100℃, esterification conversion ratio was up to 80%. Elementary Analysis, IR Spectrum and ESI-MS proved that the products mainly contained citrate monoesters. Esterification temperature was improved with the increasing of carboatomic number of fatty alcohol. Citrate monoesters had high properties on emulsion power, dispersibility and foaming power. The laws about the properties of citrate monoesters were: the surface tension and c.m.c of the products were decreased with the increasing of carboatomic numbers of fatty alcohol;dispersibility and emulsion capability were increased with the increasing of carboatomic numbers of fatty alcohol;citrate monolauryl had the best properties in foaming power and its stability than others. |
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