【作者】 焦飞鹏；

【导师】 黄可龙；

【作者基本信息】 中南大学 ， 应用化学， 2006， 博士

【摘要】 在医药领域,许多品种是手性的,在人工合成的药物中,手性药物约占一半,但目前仍以外消旋体给药为主。众多研究表明,药物对映体具有不同的药动学和药效学,因而制取高纯度的光学活性手性化合物是手性工业发展的必然要求。本文综述目前主要的手性拆分方法及其研究进展,对比各种方法的利弊,主要以β-肾上腺素类药物对映体为目标物,对三种具有代表性的手性拆分方法进行了比较详细的研究与探讨,其中关于手性液膜拆分的研究在国内至今还鲜见报道,这为外消旋体制备性拆分的研究开创一个新领域,具有很大的应用前景。主要研究工作如下:第Ⅰ部分色谱拆分采用手性选择剂固载薄层色谱拆分克伦特罗外消旋体,对流动相组成、配比和手性选择剂固载量进行考察,优化分离条件;比较手性选择剂作薄层色谱流动相添加剂和固载薄层色谱法拆分的效果,研究结果表明,手性选择剂固载薄层色谱法具有更好的手性识别能力,并从分子间作用力角度探讨手性选择剂固载薄层色谱实现拆分的分子作用模型;以β-环糊精及其衍生物为手性流动相添加剂,建立氯噻酮对映体的高效液相色谱拆分方法,着重研究拆分氯噻酮对映体的过程热力学,结合所得的热力学参数对β-环糊精及其衍生物拆分能力的差异进行比较和分析。结果表明此拆分过程都属于焓控过程,拆分能力的不同主要是因为手性添加剂与对映体形成氢键作用、空间位阻效应和立体构象匹配程度存在差异;研究萘普生外消旋体在高效液相色谱系统中的拆分,考察羟丙基-β-环糊精的浓度、流动相pH值、有机溶剂的种类及浓度、有机修饰剂浓度、不同手性流动相添加剂以及柱温等对拆分效果的影响,得到萘普生外消旋体的优化拆分条件:25mmol/L羟丙基-β-环糊精,15%乙醇,0.5%三乙胺,pH 3.5;柱温25℃;流速1mL/mim检测波长,254 nm。计算拆分过程的热力学参数,研究其色谱保留机制;采用4-乙烯基吡啶为功能单体,三甲氧基丙烷三甲基丙烯酸酯为交联剂,制备出S-萘普生的分子印迹聚合物,并用作高效液相色谱固定相,对其进行评价。研究流动相流速、不同功能单体和柱温等对拆分效果的影响,测定出分离过程的热力学参数。计算结果得出△H和△S皆为负值,并且熵的变化很小,这说明萘普生印迹分子拆分过程是焓控过程;以羟丙基-β-环糊精为手性选择剂,采用毛细管区带电泳拆分克伦特罗外消旋体。研究β-环糊精种类、浓度、缓冲液pH值及浓度、分离电压和操作温度等对分离的影响,并对分离条件进行优化:30mmol/L羟丙基-β-环糊精,50 mmol/L的磷酸盐缓冲液（pH 2.5）,分离电压24 kV,操作温度20℃,分离度可达到6.78。对手性拆分机理进行探讨,测定羟丙基-β-环糊精与两对映单体的结合常数及热力学参数,对毛细管区带电泳定量能力也进行考察。第Ⅱ部分萃取拆分以S,S-酒石酸酯为手性选择剂,研究25℃下普萘洛尔外消旋体在水相和有机相两相体系中的萃取分配行为,考察水相pH值、外消旋体初始浓度、不同溶剂和不同烷基链酒石酸酯对手性萃取性能的影响,确立了实验中较好的萃取拆分条件:S,S-酒石酸十二酯为手性选择剂,氯仿为有机溶剂,水相pH值为4.4,对映体初始浓度为5.0mmol/L,这样有机相中的对映体过量值e.e.%可大于9%。基于此条件,对萃取过程进行量热分析。第Ⅲ部分手性液膜拆分以正辛醇为有机相溶剂,D-二苯甲酰酒石酸和D-二对甲苯甲酰酒石酸的组合作为手性选择剂,使用聚偏氟乙烯中空纤维支载液膜手性分离沙丁胺醇外消旋体。考察外消旋体与组合手性选择剂的摩尔浓度比、缓冲液pH值对支载液膜手性分离性能的影响。研究表明当外消旋体与组合手性选择剂的摩尔浓度比为2:1:1时,分离因子α和对映体过量值e.e.%在实验中所能达到的最大值分别为1.49和19.74%,而较好的缓冲液pH值范围是7～7.2;基于手性配体交换原理,首次研究了在含有N-n-十二烷基-L-羟基脯氨酸和铜离子配合物为手性配体的乳状液膜体系中选择性萃取扁桃酸对映体。考察扁桃酸外消旋体浓度、手性萃取途径、有机溶剂和表面活性剂配比、从外水相到内水相pH值梯度变化以及外水相pH值等对选择性萃取性能的影响,合适的萃取拆分条件为:表面活性剂Span-80和有机溶剂按照体积比9:91混合,组成有机膜相,然后与内水相1:1体积的混和,机械乳化后形成乳状液膜,再与1:2体积的外水相混合,扁桃酸外消旋体浓度为2.0 mmol/L,手性萃取途径是从外水相到内水相,外水相pH 5.8,内水相pH 3.8,Cu²⁺浓度10 mmol/L;以D-（+）-二苯甲酰酒石酸为手性载体,首次研究了克伦特罗对映体的厚体液膜法拆分,考察D-（+）-二苯甲酰酒石酸浓度、缓冲液pH值对手性拆分的影响。建立实验中优化的手性拆分条件和动力学拆分模型。在水相pH为7和手性载体与对映体浓度比为1:4的条件下,克伦特罗外消旋体能被有效拆分,分离因子大于1.08。同时进行动力学分析,测定出膜-料液界面的萃取反应表观速率常数k₁和膜-反萃相界面的反萃取表观速率常数k₂。更多还原

【Abstract】 Pharmacologically active substance containing chiral centers can exist as pairs of enantiomers,which exhibit the same physical properties, but show a different molecular conformation.So preparation techniques for resolution of enantiomers of drug have a great interesting potential. The present main methods of chiral resolution and their research progress, advantages and disadvantages were reviewed in this paper.The three representational methods of chiral resolution were investigated and discussed in detail by taking the racemicβ-adrenergic drugs as target materials,of which the study on chiral resolution by liquid membrane was not reported in our country so far.It develops an new area for resolution of enantiomers of drug.The main contents and results can be summarized as following:The first part:Chromatographic resolutionResolution of clenbuterol enantiomers using the chiral selector impregnated thin-layer chromatography were studied,the composition and ratio of mobile phase,the quantity of impregnated chiral selector were studied,respectively.And the favourable conditions of resolution were obtained.The effects of thin-layer chromatography using mobile phase additive and chiral selectors-impregnated thin-layer chromatography were contrasted,the ability of resolution of chiral selectors impregnated thin-layer chromatography was more excellent.To investigate the behavior of chiral separation,the mechanism of resolution by impregnated thin-layer chromatography was discussed.Resolution of chlorthalidone enantiomers were established usingβ-CDs as chiral mobile phase additive.The thermodynamic parameters of chromatographic resolution were studied especially on column temperature.In addition,the different ability of resolution ofβ-CDs were compared.The results obtained indicated the enthalpic contribution to the overall chlorthalidone enantiomers transfer energy was more significant than the entropic one.The different resolution ability ofβ-CDs were determined by several interactions.However,hydrogen bond interactions played an important role in chiral resolution process.Chromatographic resolution of naproxen has been studied using HP-β-CD as chiral mobile phase additive.The effects of mobile-phase composition were researched in detail.The appropriate composition of mobile phase was 85:15(v/v)aqueous with 0.5%TEA at pH 3.5/ethanol containing 25 mmol/L HP-β-CD,and the column temperature was set of 25℃and wave length of 254 nm.The retention characteristics and separation mechanism will be discussed emphatically.The apparent thermodynamic parameters were also calculated from plots of the natural logarithm of separation factor versus reciprocal of temperature.The quantitative standard curve of naproxen enantiomers was obtained under the optimal chromatographic conditions.A chiral stationary phase for resolution of naproxen has been prepared by molecular imprinting,in which 4-vinylpyridine(functional monomer)and trimethylol propane trimethacrylate were copolymerized in the presence ofS-naproxen.Racemic naproxen was efficiently resolved on the molecular imprinting polymer.Furthermore,different functional monomers,flow rate in the mobile phase,column temperature were investigated,respectively.The thermodynamic parameters were estimated. It was found that the resolution process was enthalpy controlled.A method for capillary electrophoretic enantiomeric resolution of racemic clenbuterol has been established with HP-β-CD as the chiral selector.General equations and data analysis approach are presented to relate molibilities to equalibrium constants in simple binding equilibria and used to determine binding constants and thermodynamic parameters for host-guest complexation of clenbuterol enantiomers with HP-β-CD. The effects of type and concentration ofβ-CDs,buffer type and its concentration,pH of buffer,separation voltage and capillary temperature were investigated in detail,respectively.The appropriate conditions was: 30 mmol/L HP-β-CD,50 mmol/L phosphate solution(pH 2.5)as running buffer,separation voltage in 24 kV,and operation temperature of 20℃, the baselines separation could be obtained with resolution of 6.78.The quantitative ability of capillary zone electrophoresis also be researched.The second part:Extractive resolution Distribution behavior of propranolol enantiomers was examined in the aqueous and organic solvent of a two-phase systems containing S, S-tartaric ester as chiral selector,the influence of pH in aqueous phase, initial concentration of propranolol enantiomers,different solvent and different alkyl chain of S,S-tartraic ester on the performances of chiral extraction were investigated,respectively,the better conditions of extractive resolution were established in experiments.S, S-di-n-dodecylltartrate was used as chiral selector,chloroform was used as organic solvent,the pH in aqueous phase was about 4.4,and the enantiomers concentration was about 5.0 mmol/L.The calorimetry was analysed on this process based on the better conditions of extraction.The third part:Chiral resolution by liquid membraneResolution of salbutamol solute was carried out in liquid-supported membrane using a polyvinylidene fluoride hollow-fiber module.The enantioselective transport of solute was facilitated by combinatorial chiral selectors,which were dissolved in n-octanol organic solvent.The molar concentration ratios of salbutamol to combinatorial chiral selectors and the pH of buffer solution were investigated.The results show that when the molar concentration ratio is 2:1:1,the maximum separation factor and enantiomer excess are 1.49 and 19.74%,respectively,and the appropriate range of pH in buffer is 7～7.2.Based on the chiral ligand exchange,the enantioselective extraction of mandelic acid enantiomers was studied firstly in the emulsion liquid membranes system using copper(Ⅱ)N-n-dodecyl-L-hydroxyproline as chiral selector.The effects of initial racemic mandelic acid concentration, the direction of chiral extraction,the volume ratio of organic solvent and surfactant,the pH gradient from external to internal phase and the pH of external aqueous phase,on performances of enantioselective extraction, were discussed,respectively.Consequently,appropriate extractive conditions were established.Bulk liquid membrane containing chiral carrier was used for resolution of racemic clenbuterol,the optimal chiral separation conditions and the kinetic resolution model were established in this experiment.The influences of the molar concentration ratio of chiral carrier and pH in aqueous phase on performances of chiral resolution were investigated. The chiral resolution of bulk liquid membrane was analysed by means of a kinetic model involving two consecutive irreversible first order reactions.The pseudo-first order apparent rate constants,kl or k2 of interfacial reactions in membrane-feed solution interface or membrane-stripping solution interface were determined.The results show that the separation factor is above 1.08 under the conditions of pH 7 in aqueous phase with the molar concentration ratio of 1:4,and the kinetic resolution of clenbuterol can be evaluated by two consecutive irreversible first order reactions under the optimal conditions.更多还原