首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
提出一种新的手性分离技术双相(O/W)识别手性萃取. 研究了α-环己基扁桃酸对映体在D(L)-酒石酸异丁酯1,2-二氯乙烷有机相和β-环糊精衍生物水相萃取体系中的分配行为; 考察了β-环糊精衍生物种类和浓度、酒石酸酯构型和浓度、水相pH 值等因素对萃取性能的影响. 实验结果表明, 双相(O/W)识别手性萃取具有很强的手性分离能力, 羟丙基β-环糊精、羟乙基β-环糊精、甲基β-环糊精均对S-α-环己基扁桃酸对映体的识别能力大于对R-α-环己基扁桃酸对映体的识别能力, 其中以羟丙基β-环糊精的识别能力最强; 而D-酒石酸异丁酯的识别能力刚好相反; 在羟丙基β-环糊精和D-酒石酸异丁酯萃取体系中, α-环己基扁桃酸外消旋体一次萃取分离后, 水相中S-对映体e.e.%达到27.6%, R-和S-对映体的分配系数(kR和kS)分别为2.44和0.98, 分离因子(α)达2.49; 同时pH值和萃取剂浓度对手性分离能力有显著影响. 双相(O/W)识别手性萃取对外消旋体化合物的制备性分离有着十分重要的意义.  相似文献   

2.
利用合成的2,6-二-O-戊基-β-环糊精涂渍Symmetry C8色谱柱,研究了扁桃酸及其类似物等6 种外消旋对映体的反相高效液相色谱拆分。优化了色谱分离条件,探讨了扁桃酸的手性拆分机理。结果表明,采用优化后的甲醇-水或甲醇-0.5%三乙胺-乙酸缓冲液流动相等色谱条件,扁桃酸、扁桃酸甲酯、苯基甘氨酸、苯基琥珀酸和安息香等5种外消旋对映体达到或接近基线分离,其中前4种对映体均为(S)-构型先出峰。该法可用于实际样品的对映体纯度测定。  相似文献   

3.
双水相手性萃取拆分扁桃酸外消旋体   总被引:2,自引:0,他引:2  
研究了扁桃酸(MA)对映体在含β-环糊精(β-CD)手性选择剂的聚乙二醇(PEG)/(NH_4)_2SO_4双水相体系中的萃取分配行为.考察了pH、PEG和(NH_4)_2SO_4的质量分数、β-CD的浓度、MA的浓度与萃取温度等因素对拆分效果的影响.实验结果表明:双水相手性萃取具有很强的手性分离能力,β-CD对L-MA对映体的识别能力大于对D-MA对映体的识别能力;当温度为30℃、pH=1.0、PEG2000质量分数为30%、(NH_4)_2SO_4质量分数为20%、β-CD的浓度为0.008 mol/L、扁桃酸的浓度为0.05 mol/L时,分离因子(α)达到2.46,上、下相对映体过剩值(e.e.%)分别为42.13%和40.43%.  相似文献   

4.
几种拟除虫菊酸甲酯对映体的毛细管气相色谱手性拆分   总被引:8,自引:0,他引:8  
史雪岩  王敏  郭红超  乔振  凌云  李楠  金文戈  周景梅 《分析化学》2002,30(11):1293-1297
4种酰基化环糊精衍生物(2,6-二-O-戊基-3-O-丁酰基-β-CD、2,6-二-O-戊基-3-O-戊酰基-β-CD、2,6-二-O-戊基-3-O-庚酰基-β-CD和2,6-二-O-戊基-3-O-辛酰基-β-CD)用作毛细管气相色谱固定相,对顺式-和反式-3-(2-甲基丙烯基)-2,2-二甲基环丙烷羧酸甲酯(菊酸甲酯)、顺式-和反式-3-(2,2-二氯乙烯基)-2,2-二甲基环丙烷羰酸甲酯(二氯菊酸甲酯)、2-(4-氯苯基)-3-甲基丁酸甲酯(戊菊酸甲酯)和顺式-3-(2-氯-3,3,3-三氟丙烯基)-2,2-二甲基环丙烷羧酸甲酯(功夫菊酸甲酯)等6种拟除虫菊酸甲酯对映体进行了拆分,结果表明:所合成的4种环糊精衍生物可将顺式-和反式-菊酸甲酯、顺式-和反式-二氯菊酸甲酯、戊菊酸甲酯及顺式-功夫菊酸甲酯等6种菊酸甲酯对映体较好分离。发现不同的环糊精衍生物手性分离能力不同,溶质的结构变化对分离结果也有较大影响。  相似文献   

5.
建立了高效毛细管电泳拆分阿苯达唑亚砜对映体的方法,考察了背景电解质pH、环糊精种类和浓度,有机改性剂种类和浓度对分离的影响,对分离条件进行了优化。实验结果表明:在含36g/L磺化β-环糊精和10%甲醇的20mmol/L Tris-H3PO4(pH2.5)缓冲体系中,阿苯达唑亚砜对映体具有良好的分离效果。  相似文献   

6.
高效液相色谱手性流动相添加剂法拆分酪氨酸甲酯对映体   总被引:2,自引:0,他引:2  
分别将β-环糊精、羟丙基-β-环糊精作为手性流动相添加剂,研究了酪氨酸甲酯对映体在反相HPLC系统中的拆分,考察了流动相种类、pH和手性流动相添加剂浓度对手性拆分的影响,建立了β-环糊精手性流动相添加剂法拆分酪氨酸甲酯对映体的方法。  相似文献   

7.
β-环糊精流动相添加剂法拆分特非那丁对映体   总被引:4,自引:4,他引:4  
吴永江  方昕  朱妙琴 《分析化学》2003,31(3):332-335
以β-环糊精为手性流动相添加剂,于C18反相柱上建立了特非那丁手性对映体的高效液相色谱拆分方法。探讨了β-环糊精浓度、有机修饰剂种类及含量、流动相pH等因素对特非那丁对映体拆分的影响,结果表明:当流动相为高氯酸钠溶液(0.08mol/L):乙醇:二乙胺(75:25:0.5),pH6.2,含β-环糊精浓度为25mmol/L时特非那丁对映体得到良好分离。  相似文献   

8.
手性流动相添加剂法对两种手性化合物的直接拆分   总被引:3,自引:0,他引:3  
以β-环糊精为手性流动相添加剂,于C8反相柱上建立了2种手性农药(包括杀菌剂己唑醇和杀虫剂SR-生物丙烯菊酯)对映体的高效液相色谱拆分方法。探讨了β-环糊精浓度、流动相pH、有机改性剂种类等因素对手性拆分的影响。结果表明:在流动相为β-环糊精水溶液、磷酸钠缓冲液(0.05mol/L)、乙腈、三乙胺(体积比50:30:20:0.5)条件下,己唑醇对映体在pH为7.4,β-环糊精溶液浓度为7mmol/L时,SR-生物丙烯菊酯对映体在pH为6.4,β-环糊精浓度为10.5mmol/L时得到最佳分离。  相似文献   

9.
以二甲基-β-环糊精(DM-β-CD)为手性添加剂,用毛细管电泳法对消旋体药物尼索地平进行拆分研究。考察了二甲基-β-环糊精浓度、背景电解质种类、缓冲溶液pH值、十二烷基硫酸钠(SDS)浓度、分离电压、温度对对映体分离的影响。结果表明,以pH 8.0的30 mmol/L磷酸二氢钠-磷酸氢二钠溶液(含38mmol/L二甲基-β-环糊精,30 mmol/L SDS)为缓冲液,分离电压15 kV,毛细管温度18℃,检测波长254 nm时,尼索地平对映体达到最佳分离,分离度为1.95,对映体迁移时间分别为13.0、13.54 min。该方法简单、快速、经济,可用于尼索地平对映体的手性分离。  相似文献   

10.
利用磺酰化β—环糊精的手性化合物毛细管电泳拆分   总被引:3,自引:0,他引:3  
在毛细管电泳仪上对萘心定,苯乙二醇和β-苯基缩水甘油酸甲酯的外消旋体进行了拆分条件的研究,使用pH3.0,10mol/L的磷酸-三乙醇胺电泳缓冲液,10kV反向电压,碘酰化β-环糊精作为手性识别试剂,3种化合物的对映体获得了满意的分离度,同时发现,一定含量的甲醇可以提高中性化合物对映体分离度,该法对苯氧基环氧丙烷和苯基环氧乙烷的对映体的分离同样有效。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

13.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

14.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

15.
16.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

17.
Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.  相似文献   

18.
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.  相似文献   

19.
A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).  相似文献   

20.
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号