Study Of Synthesis And Chromatographic Separation Of 2-Hydroxypropyl-β-Cyclodextrins

2-hydroxypropyl-β-cyclodextrins were a series of the hydroxyalkylated derivations ofβ-cyclodextrin. Compared toβ-cyclodextrin, the properties of these compounds have largely been improved in the solubility, stability, bioavailability and safety. They were widely used in the pharmaceutics and analytics. In this paper, 2-hydroxypropyl-β-cyclodextrins were synthesized by propylene oxide andβ-cyclodextrin in alkali solution. The reaction synthesis process was investigated. Otherwise, prepared chromatography separation method was used to get different substituted degrees 2-hydroxypropyl-β-cyclodextrins.The influences of the reaction condition such as concentration of alkali solution, the molar ratio of raw material, the reaction time on the average substituted degrees and content of 2-hydroxypropyl-β-cyclodextrins were studied in this paper. The results showed that: 1) With the increase of alkali solution concentration, the substituted degrees increased at first and then decreased. When the alkali solution concentration was at 9%, the average substituted degrees can arrive at the largest value. The 2-OH can be substituted in the lower alkali solution, and 6-OH preferred to be received in the higher alkali solution. 2) With the mass of propylene oxide increased, the average substituted degrees also increased. When the molar ratio of propylene oxide withβ-cyclodextrin was above 14?1, the change of average substituted degrees slowed down. The contents of compounds with different substituted degree distributed symmetrically. 3) The finished reaction time was related to the concentration of alkali solution, 24 hours for 1.5% alkali solution and 72 hours for 30% alkali solution. 4) Orthogonal condition experiments demonstrated that the raw material ratio was the most distinctive factor to substituted degrees among alkali solution concentration, raw material tatio and reaction time.Three effective developed solutions were chosen out through thin layer chromatography. They were 1-propanol–water- ammonia concd (6: 3: 1, V/V), 2-propanol-water-ammonia concd (6: 4: 0.5, V/V), and ethanol-water-ammonia concd (6: 3: 0.8, V/V). Five 2-hydroxypropyl-β- cyclodextrins with different substituted degrees and positions which were derived by silica column chromatography were proved to be mono-2-O-(2-hydroxypropyl)β-cyclodextrin, di-2-O-(2- hydroxypropyl) -β-cyclodextrin,mono-6-O-(2-hydroxypropyl)-β-cyclodextrin, di-2,6-O-(2-hydroxyl-...