RP-HPLC测定不同采收期栽培何首乌蒽醌类成分

考察不同采收期青海栽培何首乌药材块根、茎、叶中蒽醌类成分的含量差异,建立RP-HPLC测定方法.采用kromasil C18柱(250 mm×4.6 mm,5 μm),V(甲醇)∶V(水)＝75∶25为流动相,在290 nm 处检测蒽醌类成分的含量.结果表明:用RP-HPLC法测定稳定、准确、可靠;青海栽培何首乌药材主要含有大黄素和大黄素甲醚两种蒽醌类成分,在何首乌块根中的含量较茎、叶中高;7月、9月采收的何首乌药材总蒽醌含量最高达到1.27%和1.29%.     

反相高效液相色谱法测定蒙成药活血六味胶囊中的大黄素

用反相高效液相色谱法测定蒙成药活血六味胶囊中的大黄素。采用KromasilC18色谱柱(4.6mm×250mm,5μm),流动相:甲醇:体积分数0.2%H3PO4溶液(85∶15),流速:1mL min;柱温25℃;检测波长:286nm。在0.042～0.925μg范围内,大黄素的量(x)与其峰面积(y)呈良好的线性关系(r=0 9991);回归方程为y=74.258x-8.714;加标回收率在97.98%～98.89%之间;RSD为0 47%。该方法可用于活血六味胶囊中大黄素的测定。     

高效液相色谱法测定贯叶连翘中的4种成分

本文利用高效液相色谱法同时测定中药贯叶连翘中绿原酸、芦丁、金丝桃苷和槲皮素四种成分的含量。采用Tiahhe Kromasil C18 100 A(5μm,250mm×4.6 mm)反相色谱柱;流动相为V(乙腈)∶V(水)=20∶80(含0.02%三氟乙酸);紫外检测波长270nm;流速1.0 ml/min;柱温40℃。绿原酸、芦丁、金丝桃苷和槲皮素线性范围分别为3.4~34μg.mL-1(r=0.9993),1.8~18μg.mL-1(r=0.9998),2.3~23μg.mL-1(r=0.9999),3.5~35μg.mL-1(r=0.9991),平均回收率(n=5)分别为98.4%(RSD=1.48%),101.8%(RSD=0.74%),103.7%(RSD=0.77%),103.5%(RSD=1.28%)。方法线性范围宽、相对标准偏差低、精密度高、重现性好,应用于贯叶连翘及制剂样品的测定,结果令人满意。     

加压毛细管电色谱分离检测虎杖根中蒽醌类成分

建立了加压毛细管电色谱法(p CEC)检测大黄酸、大黄素、芦荟大黄素、大黄酚、大黄素甲醚5种蒽醌类成分的方法,并对虎杖根中蒽醌类的成分进行分析。该方法采用EP-100-20/45-3-C_(18)毛细管色谱柱(总长度45 cm,有效长度20 cm,直径为100μm,ODS填料3μm)进行分离,流动相为20 mmol/L Na H2PO4(pH 4.7)-乙腈(15∶85),流动相的总流速为0.04 m L/min,分离电压为+5 k V,紫外检测波长为254 nm。结果表明,5种蒽醌类成分的检出限(S/N=3)为0.60~2.54μg/m L,在3.57~162.68μg/m L范围内线性关系良好,相关系数均不小于0.998 2。将所建立的方法用于虎杖中蒽醌类成分的分析,取得良好的实验结果,在低、中、高3个加标浓度下的回收率为91.1%~101.2%,相对标准偏差(RSD)为0.03%~3.6%。     

高效毛细管电泳-紫外检测法同时检测决明子中5种蒽醌类化合物

采用高效毛细管电泳-紫外检测技术研究了决明子中5种蒽醌类化合物的毛细管电泳迁移情况,并对所测对照品和供试品进行定性和定量分析。最佳分离条件为:检测波长284 nm,分离电压25 kV,进样时间5 s,运行缓冲溶液Na_2B_4O_7-H_3BO_3,浓度20 mmol/L,pH 8.50,β-环糊精浓度为5 mmol/L。在该条件下,大黄素,大黄酸,大黄酚,大黄素甲大黄素甲醚,橙黄决明素在10 min内实现分离,线性范围依次为4~350,2~350,3~300,4~400,5~400μg/mL,线性相关系数r大于0.9952,检出限分别为50.3,56.6,16.7,51.9,33.6 ng/mL(S/N=3),平均回收率在96.3%~103.6%(n=3)之间,RSD在1.4%~4.6%之间。方法可以为决明子中蒽醌类成分的分析提供一定的参考。     

高效液相色谱法测定九味石灰华散中羟基红花黄色素A和红景天苷的含量

建立了测定中药复方制剂九味石灰华散中羟基红花黄色素A和红景天苷含量的高效液相色谱方法.采用Kromasil C18色谱柱(5μm,250 mm×4.6 mm),以乙腈∶0.1%磷酸溶液(12∶88,V/V)为流动相,流速1.0 mL/min,羟基红花黄色素A的检测波长为403 nm,红景天苷的检测波长为275 nm.羟基红花黄色素A和红景天苷分别在0.288~180μg/mL和4.8~1 200μg/mL范围内呈良好的线性关系(r值为0.999 8~0.999 9),最低检出限分别为0.03μg/mL和0.5μg/mL(S/N=3),加标回收率分别为95.7%~97.4%和95.9%~98.6%.该方法简便、准确、重现性好,可用于九味石灰华散的质量控制.     

HPLC法测定虎舌红药物中的去氢飞廉碱

建立了测定虎舌红药物中喹唑酮类生物碱的HPLC方法。色谱柱为Diamonsil C18柱(250 mm×4.6 mm i.d.,5μm),流动相为V(0.2%三乙胺溶液)∶V(乙腈)=35∶65;检测波长:345 nm;流速:1.0 mL/min。结果表明,喹唑酮类生物碱可以得到有效的分离,去氢飞廉碱在0.02~0.15μg间呈线性关系(r=0.9995)。     

柱前衍生高效液相色谱法测定注射液中白消安的研究

建立了一种以二乙基二硫代氨基甲酸钠(DEDC)为柱前衍生化试剂测定白消安的反相高效液相色谱分析方法。采用C18色谱柱(250 mm×4.6 mm,5μm),以V(乙腈)∶V(水)∶V(四氢呋喃)=55∶25∶20为流动相,流速为1.0mL/min,检测波长为278 nm。白消安在119.0~892.5μg/mL范围内呈良好的线性关系,r=0.9988,回收率99.81%~99.89%。     

高效液相色谱法快速测定大黄中大黄素,大黄酸和芦荟大黄素的研究

研究了高效液相色谱法测定大黄中大黄素、大黄酸和芦荟大黄素。大黄中大黄素、大黄酸和芦荟大黄素用氯仿加热回流提取,提取液蒸干溶剂,以甲醇溶解定容待测。以安捷仑ZORBAX Stable Bound(4.6 mm×50 mm,1.8μm)色谱柱为固定相,质量分数0.1%的H3PO4和甲醇为流动相,梯度洗脱(0 min:VH3PO4∶V甲醇=27∶73;1 min:100%甲醇);在该色谱条件下,大黄素、大黄酸和芦荟大黄素在2.0 min内可达到基线分离;用紫外二极管矩阵检测器检测。方法标准回收率为99.4%~102%,相对标准偏差为1.5%~1.8%。可用于大黄中大黄素、大黄酸和芦荟大黄素的快速分析检测。     

HPLC-DAD法测定环己烷氧化产物中的二元酸

建立了高效液相色谱法测定环己烷氧化产物中丁二酸、戊二酸和己二酸含量的方法。色谱柱为ZORBAX SAX 4.6 mm×250 mm 5μm,流动相为甲醇:50 mmol/L KH2PO4水溶液=5:95(V/V),柱温:25℃,流速:1.0 mL/min。结果丁二酸、戊二酸和己二酸在10~200μg/mL范围内线性关系良好(r=0.9998,0.9996,0.9997),3种二元酸的检出限均为1.50μg/mL,目标分析物不同级别加标回收率在89.8%~102.6%之间,相对标准偏差(RSD)在1.6%~4.5%之间(n=6)。方法已用于环己烷氧化产物中有机二元酸的定量分析。     

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.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.