模拟胃液下柿叶提取物清除亚硝酸盐的研究

在模拟人体胃液条件下,采用分光光度法测定了柿叶提取液对亚硝酸盐的清除能力,研究了影响柿叶提取液清除亚硝酸盐的因素。结果表明,在模拟胃液下柿叶黄酮对亚硝酸盐具有很强的清除能力,当加入总黄酮含量为0.12mg·ml-1的柿叶提取液3m L,反应30min后,对50μg亚硝酸盐清除作用可达到99.9%。柿叶不同提取部位均有一定亚硝酸盐清除能力,其中以乙酸乙酯部位活性最好,明显优于抗坏血酸,与芦丁效果相当。     

超临界二氧化碳萃取柿叶黄酮的工艺研究

本文研究了超临界流体萃取柿叶总黄酮苷类化合物的影响因素,并对生产工艺进行了优化设计。试验结果表明:萃取时压力、温度、时间、CO2流量对萃取率的影响程度依次递减。最佳工艺条件为:萃取压力30MPa、萃取温度50℃、萃取时间3h、CO2流量30kg·h-1。用超临界流体萃取法得到的柿叶总黄酮苷类化合物萃取物纯度高,无异味,色泽金黄。     

离子色谱法测定柿叶中有机酸和无机阴离子

以0．75mmol.L^-1邻苯二甲酸和0．35mmol.L^-1三羧甲基氨基甲烷的混合溶液为淋洗液，利用单柱阴离子交换色谱法，直接电导检测，对肺叶的水溶液进行了分析，检测出柿叶中主要含有机酸是琥珀酸和苹果酸，阴离子是H2PO^-4,Cl^-,NO^-3,SO^2-4。方法简便，快速。     

超声波辅助提取柿子树叶单宁的研究

以70%的丙酮溶液为提取溶剂,采用超声波辅助提取野柿叶中的单宁,考察了超声波的功率、提取温度、提取时间等因素对单宁提取量的影响.采用响应面法对提取条件进行优化,并建立了二次回归模型.实验结果显示:当提取温度为52℃、超声波功率为80 W、提取时间为42 min,在此条件下单宁的提取量为203.15 mr/g,比无超声波...     

高效液相色谱法同时测定柿叶和连翘中黄酮和三萜类化合物的含量

建立了一种同时测定黄酮类和三萜类化合物的反相高效液相色谱法。采用Eclipse XDB-C18(150 mm×4.6 mm,5μm)色谱柱,以甲醇-乙腈-0.05%H3PO4(三乙胺调pH 3.0)为流动相,采用梯度洗脱,柱温为30℃,检测波长采用波长程序。芦丁、金丝桃苷、槲皮素、齐墩果酸和熊果酸的线性范围分别为1.632~489.6、1.045~522.5、1.349~134.9、5.290~529.0、5.075~507.5 mg/L,相关系数均大于0.999。检测限分别为0.096、0.196、0.043、0.639、0.733 mg/L。该方法可用于柿叶和连翘中黄酮和三萜类化合物的分离测定。     

反相高效液相色谱法同时测定柿叶中齐墩果酸和熊果酸

建立反相高效液相色谱法同时测定柿(Diospyros koki Linn.f.)叶中齐墩果酸和熊果酸的含量.采用Kromasil C18色谱柱(4.6 mm×250 mm,5 μm);流动相:V(甲醇):V(0.2%磷酸水溶液)=87:13;流速:0.8 mL/min;检测波长:210nm;柱温:30℃.齐墩果酸进样量在0.0848～1.696 μg范围内线性关系良好,r=0.9996,平均加样回收率为101.3%;熊果酸进样量在0.1408～2.816 μg范围内线性关系良好,r=0.9995,平均加样回收率为99.0%.3批样品测定结果表明,本法可作为柿叶中齐墩果酸和熊果酸含量测定的方法.     

非水体系中磺酸铜型树脂对有机碱的配位吸附

研究了磺酸铜型树脂在乙醇、乙酸乙酯和正己烷中对苯胺、N 甲基苯胺和N ,N 二甲基苯胺的吸附规律 ,并与水中的结果相对照 .树脂在正己烷中对苯胺等的吸附量最大 ,在乙醇、乙酸乙脂和水中依次减小 .在4种不同的介质中 ,树脂对苯胺的吸附均表现出相同的吸附选择性 ,即对苯胺的吸附亲合性最大 ,N ,N 二甲基苯胺最小 .在不同的介质中 ,树脂对苯胺的吸附基本符合Freundlich吸附方程 ,并计算了在不同介质中对苯胺吸附的吸附焓 .在水中 ,吸附速率最高 ,在乙醇、乙酸乙酯和正己烷中 ,吸附速率依次降低     

水产品中微囊藻毒素检测方法的研究进展

微囊藻毒素是蓝藻暴发中出现频率最高、产生量最大和造成危害最严重的藻毒素,具有多器官毒性、遗传毒性和致癌性。水产品中微囊藻毒素的残留会对人体产生危害,并对我国公众健康构成巨大威胁。因此,水产品中微囊藻毒素的检测和控制变得非常重要,迫切需要建立一种简便、快速、灵敏度较高的检测方法,以对水产品中的微囊藻毒素进行监控。为加强水产品中微囊藻毒素的痕量分析技术研究,对水产品中残留的微囊藻毒素开展监测,综述了国内外有关水产品中微囊藻毒素污染检测的提取、净化及分析技术进展。     

湿法磷酸中钾、钠、钙、镁的原子吸收光谱法测定

在湿法磷酸生产过程中,为了对生产流程和产品质量进行控制,有必要对湿法磷酸中微量的钾、钠、钙、镁含量进行分析。用火焰原子吸收光谱法测定湿法磷酸中钾、钠、钙、镁受基体和背景以及溶液粘度的影响很大,特别是对钙含量的测定,干扰最严重[1]。为此本文提出用离子交换树脂分离     

微波辅助提取石蒜和虎杖中有效成分的动力学模型

基于微波辅助提取(MAE)中药材中化学成分的非稳态扩散过程, 根据Fick第二定律建立了石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中白藜芦醇和大黄素微波辅助提取过程的动力学模型. 研究了提取时间、提取温度及药材粒度等因素对石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中大黄素和白藜芦醇的提取率的影响, 采用Matlab软件编程对动力学模型进行回归分析, 拟合的动力学模型与实验结果吻合. 根据模型计算了石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中大黄素和白藜芦醇在MAE提取过程中的扩散系数D, 与溶剂加热回流法(SRE)比较, 引入增强因子γ, 表征了微波对溶质分子扩散传质的影响及其对不同基质药材作用的差异.     

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.