Preparation And Characterization Of Glycosyl Phase-selective Gelators

In this paper,two glycosyl phase-selective gelators based on mannitol were prepared by different methods.The effects of reaction conditions on the yield of the glycosyl phase-selective gelators have been studied.Meanwhile,the gelation capacity of gelators has also been investigated.First of all,the modification of the lipophilic group of the mannitol was achieved by the O-esterification.The structure of the product was determined by Fourier Transform Infrared Spectrometry(FTIR),Nuclear Magnetic Resonance Spectroscopy(1H-NMR)and X-ray photoelectron spectroscopy(XPS).The ester glycosyl phase-selective gelator was prepared successfully.The highest yield of the ester glycosyl phase-selective gelator was obtained when the mole ratio of stearyl chloride and mannitol was 2.1:1,the weight ratio of triethylamine and mannitol was 0.2:1,the weight ratio of toluene and mannitol was 8:1 and the reaction lasted for 10 hours at 95 °C.The minimum gelation concentration of gelator,the time of completely gelling and the repeatability of gelling towards different kinds of oil have also been studied in detail.Then,the modification of the lipophilic group of the mannitol was synthesized by the reaction between mannitol and 2,2-dimethoxypropane in the N,N-Dimethylformamide(DMF)solution with p-toluenesulfonic acid(PTSA)as catalyst.The highest yield of the ketal glycosyl phase-selective gelator was obtained from that condition the mole ratio of 2,2-dimethoxypropane and mannitol was 2.2:1,the weight ratio of PTSA and mannitol was 0.15:1,the weight ratio of DMF and mannitol was 20:1 and the reaction lasted for 4 hours at 65 °C.The minimum gelation concentration of gelator,the time of completely gelling and the repeatability of gelling towards different kinds of oil have also been studied in detail.The results show that the minimum gelation concentration of the ketal glycosyl phase-selective gelator was lower than that of the ester glycosyl phase-selective gelator.The minimum gelation concentration of the ketal glycosyl phase-selective gelator is 0.03 g/ml,decreased by 62.5% compared with that of the ester glycosyl phase-selective gelator.