阻抑动力学光度法测定食品中痕量单宁

基于在硫酸介质中,溴化十六烷基吡啶对于溴酸钾氧化曙红Y褪色反应的增敏作用和单宁对此反应的阻抑作用,建立了阻抑动力学光度法测定痕量单宁的方法.研究了该体系的最佳反应条件和动力学参数.方法的线性范围为0.02～0.35 mg·L-1,检出限为0.01 mg·L-1,方法可直接测定茶叶和啤酒中痕量单宁,相对标准偏差在0.78%～2.36%之间,回收率在99.6%～101.0%之间.对阻抑褪色反应的机理进行了探讨.     

阻抑反应动力学光度法测定微量钙

提出了测定微量钙的阻抑反应动力学光度法。在0．012mol/L硫酸中,KBrO3氧化偶氮氯磷Ⅲ褪色,Ca^2 可阻抑该褪色反应的速度。最大吸收波长为550nm,Ca^2 浓度在0－1．4mg/L范围内与ΔSA呈线性关系,检出限0．0042mg/L。方法准确,灵敏,简便,用于直接测定水样中的微量钙,获得满意的结果。     

Sm(Ⅲ)-KBrO3-瑞士色素体系阻抑动力学光度法测定微量钐(Ⅲ)

研究发现在稀HCl介质中,微量钐(Ⅲ)对溴酸钾氧化瑞士色素褪色反应有很好的阻抑作用。据此建立了阻抑动力学光度法测定微量钐(Ⅲ)的新方法。确定了反应的最佳条件,并讨论了动力学参数。方法线性范围为0.0~0.32mg/L,检出限为6.47×10-6g/L。     

阻抑催化褪色光度法测定痕量绿原酸

在盐酸介质中 ,绿原酸能灵敏地阻抑铁 催化过氧化氢还原亮绿SF的褪色指示反应 ,据此建立了测定痕量绿原酸的阻抑 催化动力学光度分析方法。该方法测定绿原酸的线性范围为 0～ 0 .12mg/L ;检出限为4 .2× 10 -6g/L。对浓度为 0 .0 8mg/L绿原酸标准溶液 6次平行测定的相对标准偏差为 3.8% ;回收率为 93.4 %～ 10 5 %。考察了反应的最佳条件和动力学参数 ,探讨了反应机理。该方法应用于金银花浸取液中绿原酸含量的测定 ,结果满意     

阻抑-褪色光度法测定痕量间苯二酚

在NH3 NH4Cl介质中 ,间苯二酚能阻抑Fe(Ⅲ )为催化剂 ,邻菲罗啉为活化剂的过氧化氢氧化甲酚红的褪色反应。研究了该反应的最佳条件和动力学参数。建立了一种测定痕量间苯二酚的新方法。方法检出限为 3 5× 1 0 - 4 g·L- 1 ,测定范围为 0 .30mg/L～ 7.0mg/L ,方法可用于废水中间苯二酚的测定     

阻抑动力学光度法测定废水中的痕量对苯二胺

在硫酸介质中,对苯二胺能灵敏地阻抑Cu（Ⅱ）催化高碘酸钾氧化孔雀绿的褪色反应。研究了该阻抑褪色反应的最佳条件,并据此建立了测定痕量对苯二胺的阻抑催化动力学光度分析方法,对苯二胺的线性范围为0．6～4．0mg／L,检出限为0．33mg／L。将该方法应用于模拟废水中对苯二胺含量的测定,测定结果的相对标准偏差为2．1％～2,3％,对苯二胺的加标回收率为99％-103％。     

阻抑溴酸钾氧化茜素红褪色动力学光度法测定药物中水杨酸

在稀盐酸介质中,水杨酸的存在对溴酸钾氧化茜素红褪色反应有很强的阻抑作用,利用光度法监测反应过程中茜素红浓度的变化,建立了水杨酸-溴酸钾-茜素红体系阻抑动力学光度法测定水杨酸含量的方法。在选定条件下,方法的线性范围是0.008μg·m L~(-1)-1.2μg·m L~(-1),检出限为0.0017μg·m L~(-1)。     

阻抑动力学光度法测定白鼠肝脏中的超痕量镍(Ⅱ)

在 NH3- H2 O- NH4 Cl介质中 ,超痕量镍 ( )能阻抑 H2 O2 氧化甲基紫褪色的指示反应 ,研究了阻抑褪色反应的最佳条件和动力学参数 ,建立了测定超痕量镍 ( )的新方法。方法检出限为 4.4× 1 0 -11g/m L Ni( ) ,测定范围为 0～1 .0μg/2 5m L。方法已用于测定生物样品中的 Ni( )。     

二甲酚橙-KBrO_3体系阻抑反应动力学光度法测定蛋白质

在稀硫酸介质中,蛋白质可灵敏地阻抑溴酸钾氧化二甲酚橙褪色的兰多尔特(Landolt)反应,据此建立了阻抑动力学光度法测定痕量蛋白质的新方法.在优化实验条件下,于430 nm波长处进行测定,蛋白质含量在0.2～2.0 mg/L范围内与吸光度呈线性关系,检出限为0.141 mg/L,标准加入回收结果满意.     

表面活性剂增敏阻抑动力学光度法测定痕量草酸

在稀盐酸介质中，微量草酸对H2O2氧化靛红的褪色反应有显著的阻抑作用，非离子表面活性剂Triton X-100对此体系有强烈的增敏作用，据此建立了表面活性剂增敏阻抑动力学光度分析测定微量草酸的新方法。方法的线性范围是0．005-0．50mg/L，检出限为0．005mg/L。方法简便，快速，灵敏度高，用于菠菜和尿样中草酸含量的测定，结果满意。     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.