RP-HPLC/二极管阵列检测器同时测定飞机草中3种黄酮

应用高效液相色谱法/二极管阵列检测器同时测定了飞机草中木犀草素、槲皮素和山柰酚的含量。色谱柱HiQ sil C18W柱(4.6 mm×25 cm,5μm),流动相V(甲醇)∶V(水)∶V(磷酸)=50∶49.8∶0.2,检测波长槲皮素254 nm,木犀草素和山柰酚360 nm,温度30℃,流速1 mL/min,进样量10μL。确定了以超声波提取法制备飞机草分析样品的方法:溶剂为体积分数85%的乙醇,液固比为10∶1(mL/g),提取时间为1 h。结果表明,3种黄酮在0.01×10-3~0.10×10-3g/mL范围内呈现良好线性关系(R2>0.999 0),平均加样回收率分别为99.601 7%、99.032 6%和99.450 8%,RSD<2%。该方法操作简便、准确度高,可快速测定飞机草中木犀草素、槲皮素和山柰酚3种物质的含量。     

毛细管电泳紫外检测法测定莲须中的槲皮素、木犀草素、山萘酚、异槲皮甙

采用毛细管区带电泳紫外检测法(CZE-UV)同时测定中药莲须中槲皮素、木犀草素、山萘酚、异槲皮甙4种有效成分.研究了缓冲溶液的离子浓度、pH值和电压对分离度和迁移时间的影响,得到了最佳分离实验条件.在离子浓度为40 mmol/L Na2B4O7缓冲溶液(pH 9.0)中,分离电压为16 kV,波长为254 nm时,槲皮素、木犀草素、山萘酚、异槲皮甙4种物质在10 min内得到了良好的分离测定,其检出限分别为5.0、6.7、4.5和6.0 mg/L.本方法应用于实际样品的测定,结果令人满意.     

微柱高效液相色谱法测定丹参中的几种有效成分

研究了用微柱高效液相色谱法测定丹参中的4种有效成分(丹参素,原儿茶酸,原儿茶醛,丹酚酸B)的方法。丹参样品中的几种有效成分用体积分数40%的甲醇超声振荡提取,然后以WatersXterraTMRP18(1.0×50mm,2.5μm)微柱为固定相,甲醇和体积分数1%的HAc溶液梯度洗脱为流动相分离,在该色谱条件下,丹参中的4种有效成分在4.0min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97%~102%,相对标准偏差为1.6%~2.3%。用此方法可测定几种丹参样品中的有效成分。     

微柱高效液相色谱法测定苦荞中芦丁和槲皮素

研究了用微柱高效液相色谱法测定苦荞中芦丁和槲皮素的方法。苦荞中的芦丁和槲皮素用90%甲醇加热回流提取,以Waters XterraTMRP18(1.0 mm×50 mm,2.5μm)色谱柱为固定相,1%的乙酸和甲醇为流动相,在该色谱条件下,苦荞中芦丁和槲皮素在2.0 min内可达到基线分离,用紫外二极管矩阵检测器检测,方法用于4种苦荞试样中芦丁和槲皮素的测定,分析结果的RSD在0.51%~1.20%之间,回收率在98%~102%间。     

微柱高效液相色谱法测定葛根中的几种黄酮类成分

研究了用微柱高效液相色谱法测定葛根中的四种黄酮类成分。样品中的黄酮用甲醇超声振荡提取,然后用WatersXteraTMRP18(50×1.0mm,3.5μm)微柱吸附,以1%的乙酸溶液和甲醇为流动相梯度洗脱分离,用紫外二极管阵列检测器检测,结果满意。     

毛细管区带电泳法测定芹菜素木犀草素和异槲皮甙

建立了毛细管区带电泳法(CZE)分析测定芹菜素、木犀草素和异槲皮甙的方法。研究了缓冲溶液的浓度、pH、分离电压等对分离的影响。在优化条件下,三种被测物质可以在11min内实现良好的分离。芹菜素、木犀草素和异槲皮甙的峰面积与浓度分别在0.001250~0.8000,0.002500~0.1000和0.002500~0.1000g.L-1浓度范围内呈良好的线性,线性相关系数分别为0.9995,0.9995和0.9981。检出限(S/N=3)分别为0.00042,0.0005和0.00082g.L-1。并对银菊珍珠胶囊中的芹菜素、木犀草素和异槲皮甙进行了测定,结果满意。     

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。     

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。     

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。     

β-环糊精修饰区带毛细管电泳法测定野菊花中刺槐素、木犀草素和槲皮素

通过研究缓冲溶液pH和浓度、工作电压、SDS浓度和-βCD浓度等条件,建立了β-环糊精修饰区带毛细管电泳法测定野菊花中刺槐素、木犀草素和槲皮素的方法。在优化的条件下,3种物质在8min内得到良好分离。刺槐素、木犀草素和槲皮素峰面积和质量浓度分别在2~400,2~500和2~500mg.L-1范围内呈良好线性,检出限分别为0.6,0.5和0.6mg.L-1。该方法被用于分析实际样品并得到满意的结果。     

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%.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

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.