Preparation And Enantioseparation Of Dendrimer-like Chiral Stationary Phases

Enantioseparation by high-performance liquid chromatography(HPLC)based on chiral stationary phases (CSPs) has been widely investigated. In thisthesis, the approaches to separate chiral compounds and synthesize CSPs, andmechanism of enantioseparation were reviewed. Recently, in the area of CSPinvestigation, the main work is the synthesis of new type of chiral selectors soas to obtain CSPs with high chiral discrimination ability. For this purpose,some works have been conducted, which can be summarized as follows:......3-Aminopropyl silica gel was prepared by the reaction between3-aminopropyltriethoxysilane and silica gel. The preparation of dendrimer onsilica gel surface was performed by repeating two steps: (1) Michael additionof adding methyl acrylate (MA) to surface amino groups, and (2) amidation ofthe resulting esters with ethylenediamine (EDA) to get first to fourthgeneration of dendrimer-like carriers. 3-Aminopropyl silica gel and obtaineddendrimer-like carriers were characterized by FT-IR and Elemental analysis.And the results demonstrated that the synthesis of the dendrimers by thedivergent approach was successful.......A L-phenylalanine derivative was prepared through the reaction betweenL-phenylalanine and p-toluenesulfonyl chloride, followed by reacting theresultant with SOCl₂. This derivative, which was the chiral selector for CSP_1-5,was terminated with -COCl. The selector reacted with 3-aminopropyl silicagel and dendrimer-like carriers of four different generations to obtain CSP₁,CSP₂, CSP₃, CSP₄ and CSP₅. The resultants of above three synthetical reactions were characterized by FT-IR,elemental analysis and ¹H NMRspectrum. The enantioseparation ability of theses five CSPs was preliminarilyevaluated, and the results demonstrated that, among these five CSPs, CSP₄separated the most chiral compounds, and CSP₁ exhibited the best resolutionfor chiral compounds.……A(1S,2R)-(+)-2-amino-1,2-diphenylethanol (ADPE) derivative wasprepared through the reaction between ADPE and phenylene isocyanate,followed by reacting the resultant with 1, 4- phenylene diisocyanate. Thisderivative, which was the chiral selector for CSP_6-10, was terminated with-NCO. The selector reacted with 3-aminopropyl silica gel and dendrimer-likecarriers of four different generations to give corresponding fivedendrimer-like CSPs: CSP₆, CSP₇, CSP₈, CSP₉ and CSP₁₀. The resultants ofabove three synthetical reactions were characterized by FT-IR,elementalanalysis and ¹H NMR spectrum. The enantioseparation ability of these fiveCSPs was preliminarily evaluated, and the results demonstrated that, amongthese five CSPs, CSP₆ and CSP₈ separated the most chiral compounds, andCSP₆ exhibited the best resolution for chiral compounds.……Two ADPE derivatives were prepared through the reaction betweenADPE and phenylene isocyanate, followed by reacting the resultant with4,4'-methylenebis (phenyl isocyanate) (MDI) or terephthaloy chloride (TPC).These derivatives, which were the chiral selectors for CSP₁₁ and CSP₁₂respectively, were terminated with -NCO or -COCl. These two selectorsreacted with 3-aminopropyl silica gel to obtained CSP₁₁ and CSP₁₂. Theresultants of above synthetical reactions were characterized by FT-IR, elemental analysis and ¹H NMR spectrum. The enantioseparation ability oftheses two CSPs was preliminarily evaluated. A comparison ofenantioseparation ability among CSP₆, CSP₁₁ and CSP₁₂ was made. Theresults demonstrated it improved the enantioseparation ability of CSPs tointroduce more urea groups into chiral selectors.