共查询到20条相似文献,搜索用时 437 毫秒
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筛选出适合分离大豆甾醇的最佳反相色谱柱W aters symm etry C18(4.6mm×250mm)和流动相(乙腈-异丙醇,95∶5,V/V),考察了流动相配比和柱温对大豆甾醇分离的影响。从大豆甾醇产品中基线分离出豆甾醇、β-谷甾醇和菜油甾醇及菜籽甾醇这4种主要甾醇,还通过对分离出的其它多个未知峰馏分收集制备后作GC/MS分析,鉴定为γ-谷甾醇、24-β-菜油甾醇、表菜籽甾醇和豆甾醇异构体。在优化的色谱条件下,利用HPLC测定了大豆油和脱臭馏出物及大豆甾醇产品的部分样品中各甾醇组分的含量,豆甾醇和β-谷甾醇的检出限为14.4 ng和10.6 ng,HPLC测定大豆油样品中这2种甾醇的平均回收率为97.3%和96.9%。 相似文献
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采用反相高效液相色谱法,建立了检测禾谷丝核菌中麦角甾醇和羊毛甾醇含量的方法.样品经过破碎、离心、皂化后定量测定.采用DiamonsilTMC18色谱柱(250 mm×4.6 mm i.d, 5 μm i.d.),流动相为100%甲醇,流速为1 mL/min,紫外检测波长为210 nm,保留时间定性,外标法定量.麦角甾醇和羊毛甾醇的保留时间分别为21 min和27min.麦角甾醇在0.125~12.5 mg/L、羊毛甾醇在0.1~10.0 mg/L 范围内,两者峰面积与浓度均呈线性关系,相关系数分别为0.9993和0.9983.添加回收率实验表明,2种甾醇的平均添加回收率为91.8%~99.7%;相对标准偏差为2.8%~7.8%;麦角甾醇和羊毛甾醇的最小检出量分别为1.0和0.8 ng,最低检出浓度分别为0.05和0.04 mg/L.本方法准确、简便、重现性好. 相似文献
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《分析试验室》2021,40(6):654-658
建立了超高效液相色谱法(UPLC)测定柱花草中水杨酸、原苯甲酸三乙酯、吲唑、大豆甾醇B的检测方法。样品经乙酸乙酯提取,用C18固相吸附剂净化,采用Luna Omega C18(2.1 mm×100 mm,1.6μm)色谱柱分离,以20 mmol/L乙酸铵水溶液/甲醇为流动相,梯度洗脱,流速0.3 mL/min,检测波长为210 nm和240 nm,柱温:35℃,进样量1.5μL。在该色谱条件下,4种次级代谢物均呈良好的线性关系,大豆甾醇B线性范围为5.0~500μg/mL,其他3种次级代谢物线性范围为1.0~100μg/mL,相关系数r≥0.996,水杨酸、原苯甲酸三乙酯、吲唑、大豆甾醇B方法检出限分别为0.01,0.01,0.02,0.3 mg/kg,定量限分别为0.5,0.5,0.5,2 mg/kg;在3个不同浓度添加水平下,平均加标回收率为76.0%~115.1%,方法的相对标准偏差(RSDs)为1.1%~9.1%,仪器的精密度(RSDs)为0.2%~3.6%。本研究建立的方法在批量测定柱花草中次级代谢物的含量具有较好的应用前景。 相似文献
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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%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
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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%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
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. 相似文献