高速逆流色谱法从秦艽地上部分制备分离龙胆苦苷

采用高速逆流色谱法分离纯化秦艽地上部分中的龙胆苦苷。溶剂系统为V(氯仿)∶V(甲醇)∶V(水)=4∶4∶2,上相为固定相,下相为流动相,转速为800r/min,流速为2mL/min。所得产物经LC-MS分析为龙胆苦苷,纯度经高效液相色谱分析为94.0%(峰面积归一化法)。在保证分离效果的前提下,增大进样量,摸索制备分离龙胆苦苷的高速逆流色谱条件,为用高速逆流色谱法大量制备龙胆苦苷提供了一个可行方法。     

高速逆流色谱分离制备甜瓜蒂中葫芦素类化合物

采用高速逆流色谱法分离制备了甜瓜蒂中3种葫芦素类化合物.以正己烷-乙酸乙酯-甲醇-水(1.2:0.8:0.8:1.2,V/V)为两相溶剂系统,上相为固定相,下相为流动相.在主机转速800 r/min、流动相流速2.0mL/min、分离温度25℃、检测波长254nm条件下进行分离,所得产物纯度经HPLC检测,结构经MS、...     

正交轴逆流色谱法分离标准蛋白质及实际样品

 以m(质量分数为 12 .5 %的PEG80 0 0 )∶m(质量分数为 2 5 %的磷酸氢二钾 ) =1∶1或m(质量分数为 12 .5 %的PEG80 0 0 )∶m(质量分数为 30 %的磷酸氢二钾 ) =1∶1为溶剂系统 ,用下相作流动相 ,上相作固定相 ,操作时采用5 0 0r/min的转速和 6 0mL/h的流动相流速 ,考察了正交轴逆流色谱法对标准蛋白质及羊肚菌糖蛋白和枸杞糖肽的分离情况。将结果与高效液相色谱分离结果相比较 ,前者在分离度损失不大的基础上提高了进样量 ,证明了其用于制备的有效性 ,从而为分离制备天然生物大分子提供了一个新方法。     

高速逆流色谱法对独角莲中有效成分皂苷的分离纯化

本文采用高速逆流色谱法对独角莲中的有效成分皂苷进行分离纯化.分别以乙酸乙酯∶正丁醇∶乙腈∶水=5∶1∶1∶5(V/V)及乙酸乙酯∶正丁醇∶乙醇∶水=5∶10∶2∶20(V/V)为溶剂系统,用下相作流动相,上相作固定相,分别采用2 mL/min及1.5 mL/min 的流动相流速、800 r/min的转速对独角莲中的有效成分皂苷进行分离,得到纯度98%的胡萝卜苷6 mg.     

高速逆流色谱制备分离紫甘薯花色苷

采用高速逆流色谱法分离纯化紫甘薯花色苷.以正丁醇-乙酸乙酯-0.5%乙酸(3:1:4,V/V)为溶剂体系,上相为固定相,下相为流动相,流速2mL/min,进样量300mg,分离得到两种花色苷的混合物;混合物再以0.2%三氟乙酸-正丁醇-甲基叔丁基醚-乙腈(6:5:2:1,V/V)为溶剂体系,上相为固定相,下相为流动相,...     

薄层色谱图像分析定量-高速逆流色谱法快速分离制备吴茱萸中的三个生物碱类化合物

建立了薄层色谱图像分析定量-高速逆流色谱法从吴茱萸甲醇提取物中快速分离制备吴茱萸碱、吴茱萸次碱、吴茱萸卡品碱3个化合物的方法。采用数码相机对HSCCC溶剂系统上下相中的目标化合物进行TLC图像采集,使用积分软件OPSIA计算各溶剂系统对应的K值,筛选出最佳溶剂系统正己烷-乙酸乙酯-甲醇-水(3:2.5:3.5:2,V/V)。取上相为固定相,下相为流动相,检测波长为254 nm,在主机转速860 r/min、流动相流速1.5 mL/min的条件下,一次性从300 mg样品中分离制备得到经1H-NMR和13C-NMR确证的吴茱萸碱(15.3mg)、吴茱萸次碱(10.1 mg)、吴茱萸卡品碱(20.7 mg),纯度分别为93.6%,97.3%和95.1%(HPLC法)。     

高速逆流色谱分离纯化EGCG3"Me的研究

首次采用高速逆流色谱法对经自制聚酰胺初步分离的表没食子儿茶素-3-(3″-O-甲基)没食子酸酯( EGCG3"Me)样品中的EGCG3"Me单体进行分离纯化.结果表明,选择水-甲醇-乙酸乙酯-正己烷(体积比5:2:9:1)为高速逆流色谱分离的两相溶剂系统,上相为固定相,下相为流动相,在主机转速700 r／min、流速2...     

高速逆流色谱法对当归中石油醚萃取部位化学成分的分离纯化

采用高速逆流色谱法对当归石油醚萃取部位中4个主要化学成分进行分离纯化。选择Arizona溶剂体系作为高速逆流色谱分离的溶剂系统,经过实验条件优化,确定最佳溶剂为:正己烷-乙酸乙酯-甲醇-水(体积比6∶0.6∶3∶1)。高速逆流色谱分离时,采用有机相(上相)为固定相,水相(下相)为流动相,正相洗脱,流速为2mL/min,转速为900r/min,检测波长为254nm。当归石油醚萃取部位中的4种化学成分获得较好分离,经高效液相色谱检测,其纯度分别为78.5%、93.2%、98.9%、88.7%。通过1HNMR、IR和质谱分析,鉴别出其中1种化合物为藁本内酯。     

高速逆流色谱分离制备马比木中的三个喜树碱类成分

采用高速逆流色谱技术从马比木粗提物中快速分离制备喜树碱类化学成分。通过高效液相色谱测定各溶剂系统的分配系数,获得较好的分离条件。溶剂体系为:V(氯仿):V(正己烷):V(甲醇):V(水)=6:6:5:4,上相(水相)为固定相,下相(有机相)为流动相,正相洗脱;进样质量浓度:2.25 mg/mL;进样体积:20 mL;流速:2.0 mL/min;转速:800 r/min,从马比木粗提物中一次分离制备出3种单体成分。其结构经HPLC,UV,IR,ESI-MS和NMR确认和分析,分别为10-羟基脱氧喜树碱(1)、10-甲氧基喜树碱(2)和喜树碱(3),纯度分别为98.3%,99.3%,99.0%。     

高速逆流色谱分离制备厚朴的有效成分厚朴酚与和厚朴酚

建立了高速逆流色谱分离制备厚朴的有效成分厚朴酚与和厚朴酚的新方法,溶剂系统为石油醚-乙酸乙酯-甲醇-1％醋酸(5：5：7：3,V／V),上相为固定相,下相为流动相。从100mg厚朴粗提物制得和厚朴酚33．3mg,厚朴酚19．5mg,经高效液相色谱分析,纯度均大于99．5％,其化学结构由^1H NMR和^13C NMR鉴定。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.