等度反相高压液相色谱法同时测定艾叶中四种黄酮化合物的含量

建立艾叶中槲皮素、山萘酚、木犀草素、芹菜素含量测定方法。反相高效液相色谱法,色谱柱ZORBAX SB-C18(150×4.6 mm,5μm);检测波长360 nm;V(甲醇)∶V(0.2%H3PO4)=45∶55为流动相;柱温30℃;流速1.0 mL/min。槲皮素、山萘酚、木犀草素、芹菜素理论板数分别为槲皮素:大于5000山萘酚:大于6000木犀草素:大于6000芹菜素:大于7000;4种化合物的分离度均大于1.5。槲皮素、山萘酚、木犀草素、芹菜素回归曲线分别为:Y=1504.412X 9.9756,Y=1991.745X 8.6051,Y=567.591X 2.5397,Y=1811.803X 0.3074,在5.5216×10-2~19.3256×10-2μg/mL、4.608×10-2~16.128×10-2μg/mL、12.5504×10-2~43.9264×10-2μg/mL、6.0288×10-2~21.1008×10-2μg/mL范围内线性关系良好,相关系数r为0.99992~0.99998,加样回收率分别为102.0%、100.2%、100.1%、100.4%,RSD分别为2.97%、2.61%、2.66%、3.45%。样品分别含槲皮素、山萘酚、木犀草素、芹菜素0.754、0.841、1.629、0.79 mg/g。本法为艾叶提供了分析4种黄酮化合物方法,该法简便可行,重复性好,数据及结果可靠。     

高效液相色谱法同时测定不同产地及不同药用部位景天三七中4种黄酮类成分的含量北大核心CSCD

建立了同时测定不同产地及不同药用部位景天三七中槲皮素、木犀草素、山奈酚和异鼠李素含量的高效液相色谱(HPLC)法。采用TOP ODS-AQ色谱柱(250×4.6mm,5μm),以甲醇-0.1%磷酸溶液为流动相梯度洗脱,检测波长为365nm。结果表明,槲皮素、木犀草素、山奈酚和异鼠李素的浓度分别在1.90~189.90μg·mL-1(r=0.99996),1.12~112.00μg·mL-1(r=0.99998),3.71~370.56μg·mL-1(r=0.99995)和0.98~97.60μg·mL-1(r=0.99996)范围内与其色谱峰面积呈良好线性关系;平均加标回收率分别为99.79%、100.06%、100.19%和100.00%,且不同产地及不同药用部位的4个黄酮类成分在数量上或质量上有明显差异。该方法快速、准确,重现性好,可用于同时测定景天三七中槲皮素、木犀草素、山奈酚和异鼠李素含量。     

HPLC法同时测定24种花中的5种活性成分含量

建立了高效液相色谱法(HPLC)同时测定24种花中绿原酸、金丝桃苷、槲皮素、木犀草素和异鼠李素含量的方法。采用C18柱(250 mm×4.6 mm,5μm),流动相为甲醇-0.2%冰乙酸溶液梯度洗脱,检测波长350 nm,柱温35℃,流速0.8 mL/min。绿原酸、金丝桃苷、槲皮素、木犀草素和异鼠李素分别在0.0208~104.00μg/mL(r=0.99993),0.017~85.00μg/mL(r=0.99998),0.0172~86.00μg/mL(r=0.99997),0.0304~152.00μg/mL(r=0.99997),0.0168~84.00μg/mL(r=0.99986)范围内与峰面积呈良好的线性关系,平均加标回收率(n=9)92.26%~99.09%,仪器精密度(n=6)RSD均小于3.1%,方法重复性(n=6)的RSD均小于3.6%。方法可同时测定这24种花中绿原酸和黄酮类物质的含量,可作为花中活性成分定量分析的方法。     

高效液相色谱法测定北柴胡地下部分黄酮类化合物的含量

建立了高效液相色谱法测定北柴胡地下部分黄酮类化合物含量的方法。采用SepaxGP-C18色谱柱(250×4.6 mm,5μm),流动相为乙腈-0.4%磷酸(体积比35∶65),检测波长360 nm,柱温30℃,流速1.0 mL/min。结果表明,北柴胡地下部分含有槲皮素。芦丁、木犀草素、槲皮素、山奈酚、芹菜素分别在0.0050～0.0248、0.0050～0.0248、0.0051～0.0256、0.0046～0.0232、0.0054～0.0272 mg/mL范围内线性关系良好,相关系数分别为0.9957、0.9995、0.9998、0.9998、0.9998,槲皮素的平均回收率为98.34%,相对标准偏差(RSD)为0.76%。该法简便,快速,准确,重复性好,可作为北柴胡药材质量控制的方法。     

高效液相色谱法同时测定枸杞中槲皮素、山柰酚和异鼠李素

建立了高效液相色谱同时检测枸杞中槲皮素、山柰酚和异鼠李素的分析方法。样品经过甲醇超声提取后,用甲醇-25%HCl水解1 h,采用Inertsustain C18色谱柱进行分离,以甲醇-0.4%H3PO4溶液(48∶52,V/V)为流动相,进行等度洗脱,流速为1.0 m L/min,二极管阵列检测器检测,检测波长为360 nm,柱温为40℃。槲皮素,山柰酚,异鼠李素在40 min内实现分离,并分别在0.053~21.2μg/m L,0.053~4.24μg/m L和0.046~3.72μg/m L范围内具有良好的线性关系,相关系数为0.9972~0.9992,测得槲皮素、山柰酚、异鼠李素的加标回收率为99.2%~103.1%,95.6%~101.8%,93.2%~109.1%;相对标准偏差分别为0.95%~2.8%,0.55%~2.3%,0.81%~2.4%。对槲皮素、山柰酚和异鼠李素的检出限分别为0.04,0.05,0.03 mg/kg。方法可用来测定枸杞中3种黄酮苷元的含量。     

反相高效液相色谱法对秦岭21种蕨类植物中槲皮素与山柰酚含量的测定

运用反相高效液相色谱(RP/HPLC)法对21种蕨类植物中槲皮素、山柰酚的含量进行测定。使用Shimadzu C18(250 mm×4.6 mm,5μm)色谱柱,以甲醇-水溶液为流动相进行等度洗脱,流速1.0 mL/min,检测波长360 nm,进样量20μL,柱温28℃。各对照品的质量浓度与色谱峰面积线性关系良好,具有较好的精确度和重复性,槲皮素、山柰酚的加标回收率分别为93%和95%。采用该方法分别对采自秦岭的21种蕨类植物的地上和地下部分进行测定,地上部分有19种含槲皮素、15种含山柰酚,其中毡毛石韦中槲皮素含量最高(2.11 mg/g),蜈蚣草中山柰酚含量最高(19.80 mg/g);而地下部分除有边瓦韦、大瓦韦含槲皮素(含量分别为0.11、0.12 mg/g)外,其余根状茎中几乎没有这两种黄酮类化合物;表明槲皮素与山柰酚在蕨类植物的地上部分广泛存在。     

鱼腥草中3种有效成分含量的测定

建立鱼腥草不同品种、不同部位绿原酸、芸香苷和槲皮素的测定方法. 以90% EtOH为溶剂, 采用索氏提取器提取, 利用HPLC测定3种活性成分的含量. 采用DiamonsilTMC18 (4.6 mm×150 mm, 5 μm)为色谱柱, 流动相分别为0.06 mol/L V(NaH2PO4)∶V(MeOH)＝7.3∶2.7、 V(MeOH)∶V(H2O)∶V(HAc)＝48∶50∶2, 流速为1 mL/min, 绿原酸检测波长为326 nm, 芸香苷和槲皮素为254 nm. 绿原酸、芸香苷、槲皮素的线性范围分别为4.6～30.7 μg/mL、 0.30～7.5 μg/mL、 0.034～0.85 μg/mL, 平均回收率和RSD分别为99.3%、 1.0%, 98.9%、 1.6%, 98.7%、 0.7%. 该方法可用于鱼腥草原料选择和制剂质量的控制.     

高效液相色谱法测定星状凤毛菊中木樨草素的含量

采用动态微波提取技术和反相高效液相色谱法测定了星状凤毛菊中木樨草素的含量。色谱条件:色谱柱Phenomenex Fusion-Rp column(250mm×4.6mm i.d.,4μm);流动相:甲醇-0.2%磷酸水溶液(50∶50,v/v);流速:1.0mL/min;检测波长:360 nm;柱温:30℃。标准曲线方程为y=2014.93x+83.2(r=0.9997),木樨草素对照品进样量在1.2~6.0μg范围内线性关系良好。结果表明,木樨草素在星状凤毛菊中的含量为81.69μg/g。     

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。     

RP-HPLC法测定水母雪莲中木樨草素的含量

采用动态微波提取技术和反相高效液相色谱方法来测定水母雪莲中木樨草素的含量。色谱条件:色谱柱Phenomenex Fusion-Rp column(250mm×4.6mm i.d.,4μm);流动相:甲醇-0.2%磷酸水溶液(50∶50,v/v);流速:1.0mL/min;检测波长:360 nm;柱温:30℃。标准曲线方程为y=2014.93x+83.2(r=0.9997),木樨草素对照品进样量在1.2~6.0μg范围内线性关系良好。木樨草素在水母雪莲中的含量为107.10μg/g。     

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%.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

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.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

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.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

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).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

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.