高效液相梯度洗脱法测定杏香兔耳风中绿原酸和芦丁

建立了反相高效液相色谱法同时测定不同来源的杏香兔耳风中的绿原酸和芦丁。采用Kromasil C18柱(4.6 mm i.d.×250 mm,5μm),以甲醇-0.5%H3PO4的水溶液为流动相,梯度洗脱程序为0 min(30∶70)-15 min(30∶70)-20min(50∶50)-40 min(50∶50);流速0.8 mL/min;检测波长350 nm;柱温25℃;光电二极管阵列检测器(PAD)。绿原酸线性范围为0.654~5.886μg,r=0.9997,样品的平均加标回收率为98.6%,RSD 1.7%;芦丁线性范围为0.218~1.962μg,r=0.9993,样品的平均加标回收率为97.1%,RSD 2.3%。本法可作为杏香兔耳风中绿原酸和芦丁的定量分析方法。     

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。     

HPLC法测定地胆草中绿原酸的含量

建立了用高效液相色谱法测定地胆草中绿原酸含量。选择Agilent TC-C18色谱柱(250 mm×4.6 mm,5μm),甲醇-0.1%磷酸溶液(20∶80)为流动相,流速1.0 mL/min,检测波长328 nm,进样量10μL。结果表明,绿原酸0.044 9~4.488 0μg范围内线性关系良好(r=0.999 9),平均加样回收率为99.63%,RSD为0.61%(n=9)。所用方法专属性强、快速准确,可作为地胆草中绿原酸含量的测定方法。     

超声提取-高效液相色谱法同时测定新疆罗布麻茶中绿原酸和芦丁的含量

以绿原酸和芦丁的提取率为指标,选用L9(34)正交试验对新疆罗布麻茶中绿原酸和芦丁的超声工艺进行优化,并建立同时测定绿原酸和芦丁含量的反相高效液相色谱(RP-HPLC)法。结果表明,甲醇浓度是影响绿原酸和芦丁提取的显著因素;最佳提取工艺条件是:60%甲醇溶液,超声时间为40 min,超声功率为400 W,料液比为1∶25,在此条件下罗布麻茶中绿原酸和芦丁的提取率分别为0.71%和0.49%。采用Agilent TC-C18色谱柱(150×4.6mm,5μm),流动相为甲醇-0.5%冰乙酸溶液(体积比40∶60),流速为1.0 mL/min,检测波长326nm,柱温30℃。绿原酸在0.356~2.495μg(r=0.99993)和芦丁在0.317~2.218μg(r=0.99992)间呈良好线性关系;绿原酸和芦丁的平均加标回收率分别为103.41%和99.68%,其相对标准偏差(RSD,n=6)分别为0.79%和0.69%;精密度实验RSD(n=5)分别为0.27%和0.73%。     

HPLC法测定怀菊花中没食子酸的含量

为建立HPLC法测定怀菊花中没食子酸含量测定方法,采用Agilent C18柱(150 mm×4.6mm,5μm),以V(甲醇)+V(超纯水+0.1%磷酸)=25+75为流动相,流量:0.5 mL·min1;柱温为25℃,检测波长:258 nm;进样量:10μL,进行测定。结果表明,回归方程为y=3.054 2 x-2.207 1,r2=0.999 1(n=6),线性范围0～20μg,平均回收率97.28%,RSD为3.39%。样品中没食子酸质量分数为3.17 mg/g。方法快速、简便、准确、重现性较好,结果可靠,可为怀菊花中没食子酸的质量评价提供依据。     

超声辅助HPLC法测定毛泡桐中乌索酸和齐墩果酸含量

采用超声辅助提取,建立了毛泡桐中乌索酸和齐墩果酸的反相高效液相色谱分析方法。色谱柱为Kromasil C18柱(4.6 mm×250 mm,5μm),流动相为V(乙腈) V(甲醇) V(水) V(磷酸)=168 682 150 1.68,流量0.8 mL·min-1,检测波长210 nm,柱温25℃。乌索酸进样量在0.92~16.56μg时,与峰面积呈良好的线性关系(r=0.999 6),平均回收率为97.8%,RSD为1.2%(n=6);齐墩果酸在0.50~9.00μg时,与峰面积呈良好的线性关系(r=0.999 4),平均回收率为99.2%,RSD为1.5%(n=6)。该法操作简便、快速、准确,可用于毛泡桐中乌索酸和齐墩果酸含量的测定。     

高压液相色谱法测定马铃薯叶提取物中茄尼醇的含量

首次采用高压液相色谱法测定马铃薯叶提取物中茄尼醇的含量。条件为:Hypersil C18色谱柱,流动相为V(甲醇)∶V(乙醇)=80∶20,流速为1.0mL/min,紫外检测波长为215 nm,柱温30℃。实验结果表明,该方法在茄尼醇进样量1.3~4.6μg时具有良好的线性关系(Y=1685.1X 10.358,R=0.9996);加样回收实验(n=5)的平均回收率为98.2%,RSD为1.32%。     

高效液相色谱法测定双黄连制剂中绿原酸和黄芩苷

建立同时测定双黄连制剂中绿原酸(CGA)和黄芩苷(BCL)的高效液相色谱法.采用梯度洗脱,色谱柱为Waters Symmetry C18>(3.9 mm×150 mm,5μm)柱,以甲醇-0.06 mol·L-1磷酸为流动相,流速为0.8 mL·min-1,检测波长为320 nm.绿原酸的线性范围为1.72～137.6 mg·L-1,回归方程y=-28 900.12 23 036.71 x(r=0.999 6),平均回收率为95.8%,相对标准偏差为3.53%(n=7);黄芩苷的线性范围为3.35～267.9 mg·L-1,回归方程y=19 940.40 13 564.15 x(r=0.999 8),平均回收率为97.3 %,相对标准偏差为2.85%(n=7).     

金银花不同部位中绿原酸和木犀草苷含量的测定

利用HPLC法测定金银花不同部位中绿原酸和木犀草苷。采用ODS-C18色谱柱(250 mm×4.6 mm,5μm),以甲醇-水(0.03 mol/L磷酸)为流动相进行梯度洗脱,流速:1.0 mL/min,检测波长:350 nm,柱温:室温。绿原酸浓度在0~0.4 mg/mL内与峰面积呈良好线性关系(r2=0.999 6),回收率为101.9%~105.2%,相对标准偏差为3.18%(n=6)。木犀草苷浓度在0~0.1 mg/mL内与峰面积呈良好线性关系(r2=0.999 1),平均回收率为100.5%~104.0%,相对标准偏差为3.42%(n=6)。结果表明:金银花、芽等部位绿原酸和木犀草苷的含量较高。     

HPLC法测定新疆红景天根中总黄酮的含量

建立测定红景天根中总黄酮含量的HPLC法。采用Thermo-C18(4.6 mm×200 mm,5μm)为色谱柱,V(甲醇)∶V(0.4%H3PO4溶液)=50∶50为流动相,流速1.0 mL/min,检测波长360 nm,柱温25℃。槲皮素、山奈酚、异鼠李素的线性范围分别为O.0128~0.0384、0.24~0.48及0.12~0.44μg;平均回收率分别为106.30%(RSD=1.97%)、102.30%(RSD=1.69%)和100.90%(RSD=1.62%)。所建立的HPLC法可用于测定红景天属植物中总黄酮的含量。     

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.     

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.     

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.     

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.     

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.     

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.     

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.