【作者】 鲍宗必；

【导师】 任其龙；

【作者基本信息】 浙江大学 ， 化学工程与技术， 2008， 博士

【摘要】 手性药物的研究是目前国际新药开发的主要方向之一,开发手性药物单一对映体的制备或拆分技术也是制药行业亟待解决的重大课题。随着各种类型手性固定相的成功研制及商品化,以手性固定相为分离介质的制备色谱分离技术,如模拟移动床色谱,为单一对映体药物及中间体的获得开辟了新途径,是一种很有应用潜力的拆分技术。本文选取手性抗抑郁药帕罗西汀的关键中间体——帕罗醇和帕罗酮酯为研究对象,采用液相色谱和超临界流体色谱技术对其进行拆分,对色谱技术应用的基础性问题进行研究,开展了如下几方面的研究工作:1.选择对帕罗醇和帕罗酮酯对映体有较好拆分能力的手性固定相,考察流动相改性剂（包括乙醇、正丙醇和异丙醇）对色谱分离的影响,优化色谱条件,初步探讨其色谱拆分过程的手性识别机理。实验结果表明:帕罗醇和帕罗酮酯对映体在Chiralpak AD多糖手性固定相上均有较好的分离效果,帕罗酮酯对映体在Kromasil CHI-TBB酒石酸二酰胺类手性固定相上基本实现基线分离;对映体的保留因子和分离度均随改性剂含量的增加而下降,对分离因子的影响很小,帕罗酮酯在Chiralpak AD柱的保留因子随流动相极性增加反而下降的反常现象也表明氢键作用并非其主要的手性识别机理。2.以集总动力学模型为基础,利用线性色谱的矩量分析法测定不同色谱条件下帕罗醇和帕罗酮酯对映体在Chiralpak AD和Kromasil CHI-TBB手性固定相上平衡常数、轴向扩散系数以及总传质系数等模型参数。结果表明:温度变化对轴向扩散系数的影响很小,在Chiralpak AD柱上的轴向扩散系数约为10^-5数量级（cm²/s）,帕罗酮酯在Kromasil CHI-TBB柱上的轴向扩散系数为10^-4数量级（cm²/s）;本文的色谱过程属快速传质过程,理论等板高度（HETP）的50%以上来自轴向扩散;所测模型参数基本能近似描述本文的手性色谱分离过程。3.建立了一套动态法在线测定固体溶质在超临界流体中溶解度的实验装置和方法,测定了8～24MPa、308.15～328.15K范围内,帕罗醇和帕罗酮酯在超临界二氧化碳中的溶解度数据。在实验范围内,帕罗醇的摩尔分率溶解度在7.27×10^-5至1.184×10^-3之间;帕罗酮酯的摩尔分率溶解度在3.38×10^-4至4.57×10^-3之间。溶解度随着压力的上升、密度的增加而增大,等密度下溶解度随温度升高而增大。帕罗醇和帕罗酮酯的溶解度等温曲线均存在交叉点,交叉压力分别为13 MPa和14 MPa。分别采用Peng-Robinson（PR）状态方程模型和Kumar-Johnston、Chrastil以及Méndez-Santiago-Teja等半经验式方程对溶解度数据进行关联,状态方程模型关联效果较差,总体平均相对偏差（AARD）在10%以上,最高将近达29%;在三个半经验式方程中,Kumar-Johnston模型的关联效果最好,最大AARD值只有6.59%,Chrastil模型和Méndez-Santiago-Teja模型的关联效果相当,最大AARD值分别为10.12%和10.70%。4.研究帕罗西汀中间体在超临界流体色谱中的分离规律,以Chiralpak AD柱为固定相,考察改性剂类型（包括甲醇、乙醇和异丙醇）、温度和压力对保留因子、分离因子和分离度的影响规律。结果表明对映体的保留因子均随着改性剂含量的增加而显著下降,当改性剂含量大于10%（v%）时,保留因子的下降趋势变缓;分离帕罗酮酯时,异丙醇作改性剂的分离度和分离因子均最大,分离帕罗醇对映体时,甲醇是最佳的改性剂。保留因子和分离度均随压力的增加而减小,异丙醇作改性剂时,保留因子随温度的升高而增大;甲醇作改性剂时,压力＜18MPa下保留因子随着温度的升高而增大,压力≥18MPa下保留因子随着温度的升高而减小。分离因子几乎不受压力变化的影响,随着温度的升高而下降,低温对分离有利。5.借鉴液相色谱分离过程的集总动力学模型,提出将轴向扩散对色谱峰展宽的贡献归结于表观总传质系数,由线性色谱的理论等板高度方程对总传质系数进行估算。采用特征点洗脱法研究SC-CO₂状态下（+）和（-）-帕罗醇对映体在Chiralpak AD手性固定相的吸附平衡关系,实验结果表明吸附量随压力的升高而减小,而温度升高吸附量的变化很小。结合所得的传质参数与吸附平衡关系,通过色谱模拟预测色谱流出曲线,其结果与实验点吻合良好。更多还原

【Abstract】 Future directions in modern drug discovery will be focused on the development of chiral drug candidates. To explore new technologies for resolution and preparation of optically pure enantiomers is also a critical challenge to pharmaceutical industry. As an increasing number of chiral stationary phases have been developed and some of them are commercially available, preparative chromatography based on chiral stationary phase, such as simulated moving bed chromatography, has received significant attention and is now considered as a powerful approach for preparation of single-enantiomer drugs or chiral intermediates. In this work, the key intermediates of paroxetine trans-（±）-4-（4’-fluorophenyl）-1-methylpiperidine （1） and trans-（±）-3-ethoxycarbonyl-4-（4’-fluorophenyl）-1-methylpiperidine-2,6-dione （2） were resolved by chiral liquid chromatography and supercritical fluid chromatography. Some fundamental issues were studied. The details are summarized as follows.1. The performance of different chiral stationary phases for the racemic compounds 1 and 2 were compared by HPLC. The effects of the alcohol modifier including ethanol, 1-propanol and 2-propanol on enantioseparation were investigated. It was found that compounds 1 and 2 were well separated on Chiralpak AD-H and that only compound 2 can be baseline resolved on Kromasil CHI-TBB. Retention factor and resolution for all enantiomers decreased with the content of modifier increased, while minor variation in enantioselectivity was observed. For compound 2, an unusual phenomena, i.e., the retention of enantiomer on Chiralpak AD-H increased when the alcohol modifier was changed from 2-propanol to ethanol, was found. This implied that the chiral discrimination mechanism did not lie in hydrogen bonding.2. The equilibrium constants and axial dispersion and mass transfer coefficients were determined by moment analysis based on the lumped kinetic model for linear chromatography. The results show that axial dispersion coefficient did not change obviously as the temperature varied. In case of Chiralpak AD-H, the axial dispersion coefficients for both enantiomers are about 10^-5 cm²/s, while it is about 10^-4 cm²/s for compound 2 on Kromasil CHI-TBB column. Fast kinetics of mass transfer in both chiral stationary phases was observed and more than 50% of height equivalent of theoretical plate （HETP） comes from axial dispersion. The model parameters obtained were utilized to simulate the elution profiles and the simulated and experimental results match well. 3. A flow-type apparatus has been established for solubility determination of solid in supercritical CO₂. The solubility of paroxetine intermediates in supercritical CO2 was measured in the pressure range from （8 to 24） MPa and at temperatures of （308.15, 318.15, 328.1） K. Results showed that under the present operation conditions, the solubility of compound 1 and 2 were in the range of (7.27×10^-5 to 1.184×10^-3) and (3.38×10^-4 to 4.57×10^-3) in mole fraction, respectively. The solubility increased with rising pressure or density at constant temperature as well with temperature increased at constant density. The crossover pressure for compound 1 and 2 can be found at about 13 and 14 MPa, respectively. The experimental solubility data were correlated with the Peng-Robinson equation of state with an AARD above 10%, besides empirical equations of Kumar-Johnston, Chrastil and Méndez-Santiago-Teja were also used to fit the data with an AARD of 6.59%, 10.12% and 10.70%, respectively.4. Separation of paroxetine intermediates by chiral supercritical fluid chromatography was studied. The effect of pressure, temperature and type of modifier in mobile phase on the retention factor, selectivity and resolution was investigated. It was found that retention for both enantiomers decreased markedly as modifier concentration rose up to 10% （vol%）. In the case of racemate 2, better resolution was obtained when using 2-propanol as modifier in the place of methanol and ethanol, while for racemate 1, methanol provided the best performance. Both retention and resolution decreased with increase in pressure. When using 2-propanol as modifier, enantiomers were more retained as the temperature increased. Nevertheless, in the case of methanol as modifier, retention factor only increased with temperature increased at the pressure below 18 MPa. Increasing pressure had little significant effect on the selectivity, and lower temperature was favorable to the enantioseparation.5. The lumped kinetic model for liquid chromatography was adopted to describe the chromatographic process in supercritical fluid by introducing all band broadening effects to the overall mass transfer coefficient, which can be estimated from the equation of HETP. Adsorption isotherms of both enantiomers of compound 1 on Chiralpak AD from supercritical fluid were determined by a characteristic point （ECP） method. It was observed that adsorption capacity decreased with the increasing pressure, and minor variation was found when the temperature altered. With the adsorption isotherms and mass transfer coefficients obtained, the simulated elution profiles showed a good agreement with the experiments.更多还原