Preparation and chiral recognition ability of crosslinked beads of polysaccharide derivatives

The spherical beads consisting of cellulose 3,5-dimethylphenylcarbamate with partial hydroxyl groups were prepared to be used as chiral packing materials (CPMs) for HPLC. The beads were obtained without using macroporous silica gel, which is usually used as the support of the CPMs based on the polysaccharide derivatives. After the crosslinking in the bead with diisocyanates, such as 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate (DBDI), tolylene-2,4-diisocyanate (TDI), and m-xylylene diisocyanate (XDI), the obtained beads were packed into an HPLC column. As the content of the hydroxyl groups of the cellulose derivatives decreased, the obtained CPM exhibited a higher chiral recognition ability. The beads possessed a higher loading capacity than the CPM prepared by coating the cellulose derivative on silica gel. The crosslinked beads could be used with the eluent containing chloroform. The amylose derivative beads were also prepared as a CPM for chiral HPLC.     

Preparation of novel chiral stationary phase based on click chemistry for ligand exchange chromatography

Click chemistry was applied to immobilize L-proline derivative onto azide-modified silica gel to give a novel chiral stationary phase(denoted as click-CSP) for ligand exchange chromatography.The developed protocol combines the benefits of operational simplicity,exceptionally mild conditions and high surface loadings.The enantioselectivityαof some DL-amino acids on the click-CSP were found to be in the range from 1.13 to 3.46.The chromatographic resolutions of some DL-amino acids and the stability study f...     

Improved preparation of chiral stationary phases via immobilization of polysaccharide derivative‐based selectors using diisocyanates

The classical method for the preparation of immobilized polysaccharide‐based chiral stationary phases (CSPs) with a diisocyanate was improved. Cellulose or amylose was directly coated onto 3‐aminopropyl silica gel after it was dissolved in a mixture of N,N‐dimethylacetamide, LiCl, and pyridine, then immobilized onto silica gel with a diisocyanate, and finally allowed to react with an excess of corresponding isocyanate. Four polysaccharide derivatives, 3,5‐dimethylphenylcarbamate and 3,5‐dichlorophenylcarbamate of cellulose, and 3,5‐dimethylphenylcarbamate and 5‐chloro‐2‐methylphenylcarbamate of amylose, were immobilized onto silica gel utilizing this method. Compared with the classical diisocyanate method, the improved procedure avoided the derivatization and regeneration of 6‐hydroxyl groups of cellulose and amylose, and thus showed an advantage for simple and economical preparation. The relationships among the amount of diisocyanate used, immobilization efficiency, and enantioseparation on the cellulose‐based CSPs were investigated. Also, the solvent durability of the obtained CSPs was examined with eluents containing chloroform or THF. By utilizing these eluents, the chiral recognition abilities of the obtained CSPs for some of the tested racemates were improved.     

Preparation and chromatographic characteristics of a novel 2,6-dimethyl-β-CD bonded HPLC chiral stationary phase

A novel 2,6-dimethyl-b-CD bonded and silica based HPLC chiral stationary phase（CSP） was prepared.The diphenylmethane diisocyanate（MDI） was applied for the first time in the immobilization of 2,6-dimethyl-b-CD onto the surface of aminized silica gel under mild conditions. The composite materials obtained were used as the CSP for chiral separation processes and this kind of CSP exhibits good enantioselectivity for a variety of chiral compounds under reversed-phase conditions.     

Quinine Derivative Bonded the Hybrid Mesoporous Silicas Chiral Stationary Phase: Preparation and Application in Liquid Chromatography

A novel chiral stationary phase (QN‐APEPMOs) was synthesized by immobilizing quinine derivative (QN) onto spherical ammoniapropyl‐functionalized ethane‐bridged periodic mesoporous organosilicas (APEPMOs). The mesoporous material was prepared by a one‐step co‐condensation of 1,2‐bis (triethoxysilyl) ethane (BTSE) and 3‐ammoniapropyl triethoxysilane (KH‐550) using cetyltrimethyl‐ammoniumchlorine (C₁₈TACl) as a template with the aid of ethanol (co‐solvent) in basic medium. And O‐9‐(tert‐butyl carbamoyl) quinine derivative was immobilized on APEPMOs particles through the vinylic double bond. All of the products were characterized. The results showed that APEPMOs were perfect substrates for chiral stationary phase (CSP) and quinine moieties have been successfully immobilized onto the silica gel. To evaluate the chiral discrimination ability of the synthesized CSP, some analytes have been investigated on QN‐APEPMOs in high performance liquid chromatography (RP‐HPLC) in reversed phase. Three acidic compounds were baseline separated. The results demonstrated that QN‐APEPMOs had high selectivity for acidic compounds such as: carboxylic and sulfonic acids. And the reproducibility of the chiral column was good, while the stability was not very good.     

Preparation and chiral recognition in HPLC of cellulose 3,5-dichlorophenylcarbamates immobilized onto silica gel

The 3,5-dichlorophenylcarbamates (2) of cellulose bearing a small amount of 3-(triethoxysilyl)propyl residues were synthesized by a one-pot process and immobilized onto a silica gel through intermolecular polycondensation of the triethoxysilyl groups. The obtained cellulose derivatives were characterized by (1) H NMR and elemental analysis (EA), and their recognition abilities were evaluated by high-performance liquid chromatography (HPLC). The cellulose derivatives containing about 1-5% of the 3-(triethoxysilyl)propyl residue were efficiently immobilized with a high chiral recognition ability. The immobilized chiral packing materials (CPMs) could be used with the eluents containing chloroform and tetrahydrofuran (THF), which cannot be used with the conventional coated-type chiral packing materials. By using these eluents, the chiral recognition for many racemates was improved.     

新型衍生化β-环糊精键合硅胶手性固定相的合成与性能研究

合成了苯基氨基甲酸酯全衍生化β-环糊精键合硅胶手性固定相.在正相色谱条件下,对系列2-(噻唑基)-α-氨基膦酸酯化合物进行了有效的手性拆分研究.结果表明,所有化合物都得到基线分离,对映异构体选择性α>1.2,为制备型液相色谱的手性拆分提供条件.     

Preparation and chiral recognition of a novel chiral stationary phase for HPLC,based on mono（6A-N- 1-（2-hydroxyl）- phenylethylimino-6A-deoxy）-β-cyclodextrin and covalently bonded silica gel

A novel chiral stationary phase （CSP） was prepared by immobilizing mono（6A-N-1-（2-hydroxyl）-phenylethylimino-6A- deoxy）-β-cyclodextrin onto the surface of silica gel via a longer spacer. This chiral stationary phase exhibited good enantioselectivity for a variety of chiral compounds under reversed-phase conditions.     

D-苯甘氨酸手性固定相的制备及对多种手性化合物的拆分

以D-3,5-二硝基苯甲酰苯甘氨酸和3-氨丙基硅烷化硅胶合成了D-苯甘氨酸衍生手性固定相,并自制了手性高效液相色谱分离柱,用正己烷-异丙醇作流动相,对非衍生化的氨基酸、胺、醇和羧酸类等10种手性化合物进行了高效液相色谱拆分。结果表明:所拆分的10种手性化合物,有7种手性化合物能得到基线分离,最好的分离度Rs=5.56。该文还用苯对柱性能进行了评价,理论塔板数达每米8万块。     

复合型多糖类手性固定相的制备及其手性识别能力

将纤维素三(3,5-二甲基苯基氨基甲酸酯)(cellulose tris(3,5-dimethyIphenylcarbamate),CDMPC)和淀粉三(3,5-二甲基苯基氨基甲酸酯)(Amylose tris(3,5-dimethylphenylcarbamate),ADMPC)分别涂敷于氨丙基硅胶上然后混合,或者将...     

直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)手性固定相分离硒代甘油醚对映体

合成出了直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)手性固定相.用该固定相首次拆分了一系列硒代甘油醚对映异构体.讨论了流动相组成和样品结构对保留和拆分的影响.     

涂敷纤维素类手性固定相对甲霜灵中间体的高效液相色谱拆分

通过在自制的球形氨丙基硅胶上涂敷纤维素－三（3，5－二甲基苯基氨基甲酸酯）（CDMPC）制备了手性固定相，并采用该手性固定相成功地对甲霜灵中间体进行了高效液相色谱拆分；考察了由不同比例的正己烷和异丙醇组成的流动相对甲霜灵中间体分离效果的影响。     

Preparation and HPLC application of chiral stationary phase from 4‐tert‐butylphenylcarbamates of cellulose and amylose immobilized onto silica gel

The 4‐tert‐butylphenylcarbamates of cellulose and amylose bearing a small amount of 3‐(triethoxysilyl)propyl residues were synthesized by a one‐pot process and efficiently immobilized onto a silica gel through intermolecular polycondensation of the triethoxysilyl groups. The obtained chiral packing materials (CPMs) were evaluated by HPLC. The polysaccharide derivatives containing about 1–2% of the 3‐(triethoxysilyl)propyl residue were efficiently immobilized with a high chiral recognition ability. The immobilized CPMs could be used with the eluents containing chloroform and tetrahydrofuran (THF), which cannot be used with the conventional coated‐type CPMs. By using these eluents, the chiral recognition for many racemates was improved.     

L-苏氨酸手性分子印迹硅胶分离固定相的制备及分离性能研究

本文使用堆砌硅珠法以硅溶胶为原料、苏氨酸(L-Thr)为手性源构造手性环境,制备具有手性分离能力的全无机介孔手性硅胶球,对其进行元素分析、红外光谱法分析、透射电镜、扫描电镜和氮气吸附等表征,采用HPLC法探究无机介孔硅胶球制备的固定相对手性异构体和苯系位置异构体的拆分性能,成功分离了9对外消旋化合物和8种苯系位置异构体。L-Thr手性硅胶球在手性分离方面具有一定的可行性,并且在位置异构体的分离上具有良好的分离性能,色谱的重复性良好。     

几种手性醇在纤维素键合的SBA-15基手性固定相上的直接拆分

在强酸性条件下, 以三嵌段聚醚P123为模板, 合成了孔径大且粒径均匀的SBA-15介孔二氧化硅微球. 将含有少量三乙氧硅丙基氨基甲酸酯残基的纤维素-三(3,5-二甲基苯基氨基甲酸酯)通过分子间缩聚作用固载到氨丙基化的SBA-15微球上, 制得手性固定相; 采用常规和非常规的流动相模式, 对一些芳香醇的消旋体进行了手性拆分. 实验结果表明, 所制备的SBA-15微球不仅分散性良好, 具有规则的二维六方孔道结构, 而且消除了微孔; 所制备的键合手性固定相不仅固载手性选择剂的量大, 而且经六甲基二硅胺烷封端后可有效改善拖尾现象, 对实验选用的手性醇具有较高的拆分能力; 与大孔硅胶为基质的同类纤维素键合手性固定相相比, 该固定相对同种手性消旋体的分离因子明显提高.     

衍生化纤维素手性固定相分离硫代和硒代甘油醚对映异构体

将纤维素-三(3,5-二甲基苯基氨基甲酸酯)涂敷于氨丙基硅胶上制得了一种高效液相色谱手性固定相.用该固定相首次拆分了18种单硫代、单硒代和双硫代甘油醚对映异构体.讨论了流动相组成和样品结构对保留和拆分的影响.     

Reversed-phase separations on cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase

Summary The chiral separation of eight racemic compounds has been investigated on a cellulose tris(3,5-dimethylphenylcarbamate) chiral column under reversed-phase conditions. The discrimination mechanism under reversed-phase conditions is discussed. Addition of acid to the mobile phase is necessary for resolution of acidic racemic compounds. The presence of ion-pair reagent in the mobile phase is a key factor in the resolution of basic racemic compounds. Retention of the racemates is also affected by addition of acid or salt. The anion in buffer not only interacts with the racemete, but also with the polysaccharide derivative on the silica gel surface.     

Novel Pirkle-type quinine 3,5-dinitrophenylcarbamate chiral stationary phase implementing click chemistry

A new Pirkle-anion exchange hybrid-type chiral stationary phase (CSP-1) has been synthesized by immobilizing 10,11-didehydroquinine 3,5-dinitrophenylcarbamate onto 3-azidopropyl silica gel using click chemistry (1,3-dipolar Huisgen cycloaddition). This chiral selector and CSP contain a strong π-accepting 3,5-dinitrophenyl residue besides the π-basic quinoline group and an ionizable tertiary amino group. In concert with ion pairing it offers π-donor-π-acceptor interactions resulting in an enhancement of the selectivity toward specific π-donating analytes such as aryloxypropionic acids and profens. A representative set of these analytes has been investigated under various chromatographic conditions (polar-organic, reversed- and normal-phase) leading to base-line enantioseparations with selectivity (α) values up to 1.8. Control experiments with related quinine tert-butylcarbamate phase grafted onto the surface either by thioether (Chiralpak QN-AX) or 1,2,3-triazole linker revealed the impact of the additional aromatic moiety in the chiral selector motif.     

Effect of Chiral Additives in the Preparation of Cellulose-Based Chiral Stationary Phases in HPLC, and Effect on Enantiomer Resolution

Chiral stationary phases (CSPs) for high-performance liquid chromatographic (HPLC) have been prepared by coating silica gel with cellulose tribenzoate or cellulose trisphenylcarbamate. The effect of chiral additives on preparation of the CSPs was studied with (+)-l-mandelic acid, (−)-2-phenyl-1-propanol, (+)-1-phenyl-1,2-ethanediol and (−)-1-(1-naphthyl)ethanol as chiral additives for cellulose tribenzoate and (−)-2-phenyl-1-propanol and (+)-phenylsuccinic acid as chiral additives for cellulose trisphenylcarbamate. The results showed that chiral recognition by these stationary phases was increased in comparison with the original CSPs, especially the resolution (R _S) obtained. The method can be used to improve the efficiency of enantiomer separation by silica gel stationary phases coated with polymers.     

Immobilization of 3,5‐dimethylphenylcarbamates of cellulose and amylose onto silica gel using (3‐glycidoxypropyl)triethoxysilane as linker

The 3,5‐dimethylphenylcarbamates of cellulose and amylose were effectively immobilized onto plain silica gels as chiral packing materials (CPMs) for HPLC by means of intermolecular polycondensation of triethoxysilyl groups introduced with (3‐glycidoxypropyl)triethoxysilane. The immobilization and chiral recognition abilities of the obtained CPMs prepared with different amounts of (3‐glycidoxypropyl)triethoxysilane were investigated. In addition, the solvent compatibilities of the immobilized‐type CPMs were examined with eluents containing chloroform and THF. When these eluents were used, for most of the tested racemates, the chiral resolving abilities of the obtained CPMs were improved.