Preparation And Properties Of Glycosyl Gelators

In this paper,two phase-selective gelators based on mannitol and D-arabinose were synthesized by the modification of different lipophilic groups.The influences of different reaction conditions on the yield of two phase-selective gelators have been investigated.And the gelation ability of the gelators to different oils and organic solvents has also been studied.Firstly,mannitol-based gelators were synthesized by the reaction between mannitol and 1,1-dimethoxycyclohexane in the N,N-Dimethylformamide(DMF)solution with p-toluenesulfonic acid as the catalyst.The structure of the product was determined by Nuclear Magnetic Resonance Spectroscopy(~1H-NMR)and Fourier Transform Infrared Spectrometry(FTIR).The highest yield of the mannitol-based gelator was obtained when the molar ratio of 1,1-dimethoxycyclohexane and mannitol was 2.2:1,the weight ratio of p-toluenesulfonic acid and mannitol was 0.15:1,the weight ratio of DMF and mannitol was 26:1 and the reaction lasted 4.5 hours at 65°C.The minimum gelation concentration of the mannitol-based gelator,the time of completely gelling and the repeatability of gelling towards different kinds of oils and organic solvents have been studied in detail.The results show that the minimum gelation concentration of the mannitol-based gelator towards tetrachloromethane is0.05 g/mL and the time of completely gelling is 8 min.Secondly,D-arabinose based gelators were synthesized by the reaction between D-arabinose and 2,2-dimethoxypropane in the DMF solution with p-toluenesulfonic acid monohydrate as the catalyst.The structure of the product was also demonstrated by ~1H-NMR)and FTIR.The highest yield of the D-arabinose-based gelator was obtained when the molar ratio of 2,2-dimethoxypropane and D-arabinose was 3:1,the weight ratio of p-toluenesulfonic acid monohydrate and D-arabinose was 0.015:1,the weight ratio of DMF and D-arabinose was 7.5:1 and the reaction lasted 3.5 hours at30°C.The minimum gelation concentration of the gelator,the time of completely gelling and the repeatability of gelling towards different kinds of oils and organic solvents have also been studied in detail.The results show that the reaction condition of the D-arabinose based gelators were relatively milder than that of the mannitol-based gelators.And the minimum gelation concentration of the D-arabinose based gelator is lower than that of the mannitol-based gelator.The minimum gelation concentration of the D-arabinose-based gelator towards toluene is 0.035 g/ml,which decreased by 61%compared with that of the mannitol-based gelator.