催化动力学极谱法测定痕量甲醛

在稀硫酸介质中,痕量甲醛对溴酸钾氧化甲基红的反应有很强的催化作用.而甲基红及其氧化产物均能在滴汞电极上产生灵敏的极谱吸附波,其峰电位依次为-0.57 V及-0.49 V(vs.SCE).在-0.57 V处测得的甲基红的峰电流的二阶导数值与反应体系中的甲醛浓度在0.2～6.5 mg·L-1之间呈线性关系,方法的检出限为0.041 mg·L-1,对2.5 mg·L-1甲醛测定8次,得出RSD值为1.8%,标准加入法回收率试验的结果在97.0%～104.0%之间.     

单扫描极谱法测定注射液及血清中维生素K1

建立了维生素K1的极谱测定方法.在0.05 mol·L-1 NH4Cl-NH3(pH 8.58)缓冲溶液中,维生素K1可产生一极谱还原峰,峰电位Ep为-0.39 V ;其二阶微分峰峰电流ip″与维生素K1的浓度在1.1×10-7 ～2.2×10-5 mol·L-1范围内呈线性关系,相关系数r=0.998 6(n= 9 );方法的检出限为4.0×10-8 mol·L-1.13次平行测定2.2×10-5 mol·L-1维生素K1还原波二阶导数峰峰电流ip″的相对标准偏差(RSD)为1.83%.本法可直接用于注射液及血清中维生素K1含量的测定.     

单扫描示波极谱法测定药物中头孢曲松钠含量

研究了用单扫描示波极谱法测定药物中头孢曲松钠含量的方法。pH 4．5的草酸-草酸钾缓冲溶液中,头孢曲松钠在-768 mV(vs．SCE)处有一灵敏的极谱还原峰,在6～18 mg·L1范围内呈良好的线性关系。样品测定结果与药典中HPLC法相比较,相对偏差为0．74％,加标回收率在90．0%～120．0%之间。     

吡啶阳离子表面活性剂的示波极谱测定方法研究

在 0 .0 4mol·L- 1Na2 HPO4 KH2 PO4 (pH 8.0 )底液中 ,氯化十六烷基吡啶在汞电极上峰电位 - 1.35V(vs .SCE)处产生灵敏的还原波 ,其浓度在 0～ 0 .6mg·L- 1范围内与极谱波二阶导数的峰高 (H)呈正比 ,检出限 (3S/k)为 0 .0 1mg·L- 1。该极谱波具有吡啶阳离子表面活性剂的典型特征 ,特异性强 ,多种共存物质无干扰。用于生活饮用水中吡啶阳离子表面活性剂总量的测定 ,获得了满意的结果     

硒(Ⅳ)的示波极谱测定

在0.2mol·L-1的甲酸 甲酸钠缓冲液(pH3.5)中,硒(Ⅳ)于-0.70V(vs.SCE)处有一灵敏的极谱波。在1×10-5～0.5g·L-1范围内峰电流与其浓度呈线性关系,检出限为1×10-6g·L-1,加标回收率为95.0%～114.5%,相对标准偏差为4.44%～7.39%。方法适于试样中微量硒的测定。     

Sn(Ⅳ)-PAN极谱络合吸附波的研究

在乙酸-乙酸钠缓冲溶液中(pH 4.4),锡与1-(2-吡啶偶氮)-2-萘酚(PAN)形成电活性络合物,在单扫描极谱仪上,于-0.61 V(vs.SCE)处产生一灵敏的导数极谱波,其峰电流与5.0×10-9~2.0×10-6mol.L-1锡浓度呈线性关系,检出限达2.0×10-9mol.L-1。用等摩尔连续变化法测得络合物的摩尔比为nSn(Ⅳ)∶nPAN=1∶2。机理研究表明,极谱波为吸附在电极表面的络合物中PAN还原产生。此法可用于测定罐头食品中锡,测定结果的RSD值小于4%,回收率为98%~103%。     

锌(Ⅱ)-邻菲罗啉络合物的极谱行为及应用

在0.075 mol.L-1硼酸-氢氧化钠的缓冲溶液中(pH 8.9),锌(Ⅱ)与邻菲罗形成的络合物是电活性的,于-1.30 V(vs.SCE)产生较灵敏的极谱峰,峰电流与锌(Ⅱ)浓度在4.0×10-8~2.0×10-6mol.L-1之间存在线性关系(r=0.998 6),检出限为2.0×10-8mol.L-1。利用线性扫描极谱法探讨了极谱峰的电化学性质及电极反应机理,并将该法成功应用于测定葡萄糖酸锌口服液中锌的含量。     

酸性铬蓝K-蛋白质结合反应体系的极谱分析

酸性铬蓝K(ACBK)在pH3.0Britton Robinson(B R)缓冲溶液中,于-0.41V(vs.SCE)产生一个灵敏的线性扫描二阶导数极谱峰。当在上述溶液中加入人血清白蛋白(HSA)后,由于HSA带正电,而ACBK带负电,两者之间主要通过静电引力形成一种超分子复合物,该复合物无电化学活性,使ACBK在溶液中的游离浓度降低,相应其在-0.41V处的极谱峰电流降低。优化了结合反应的条件和电化学测定条件。在最佳条件下,峰电流的降低值与HSA的加入量在3.0～20.0mg·L-1范围内呈线性关系,应用于人血清样品的测定,试验结果同考马斯亮蓝光度法一致。     

表面活性剂增敏2.5次微分极谱测定香豆素

拟定了表面活性剂增敏、2 .5次微分极谱测定香豆素的方法。在含 6.0× 10 -6 mol·L-13 氯 2 羟丙基 三甲基氯化铵的 0 .1mol·L-1KH2 PO4 Na2 HPO4 (pH 6.8)缓冲液中 ,香豆素还原波 [峰电位Ep=- 1.60V(vs .SCE) ]的 2 .5次微分极谱峰峰电流e″p 与其浓度在 4 .0× 10 -7～ 6.0× 10 -5mol·L-1范围内呈良好线性关系 (r =0 .9998,n =10 ) ,检出限为 1.2× 10 -7mol·L-1。 13次平行测量 8.0× 10 -6 mol·L-1香豆素的峰电流 ,RSD为 1.5 %。该方法可用于中药白芷中香豆素的直接测定     

级联人工神经网络结合单扫描示波极谱法同时测定对硝基氯苯和邻硝基苯酚

在pH 6.5的0.3 mol·L-1氯化钾介质中,在电位值-0.71 V 及-0.74 V处可分别见到对硝基氯苯及邻硝基苯酚的灵敏极谱峰,可分别对此两种化合物进行测定,但因两者相互干扰不能在混合物中同时测定.将改进的小波神经网络与BP神经网络相结合,提出一种新的混级联神经网络结构,并用于单扫描示波极谱法同时测定对硝基氯苯和邻硝基苯酚.通过对网络结构的优化和网络参数的调整,加快了训练速度,提高了预测的准确度.该法用于混合样品中同时测定对硝基氯苯和邻硝基苯酚,其相对误差和回收率分别为3.76%,96.2%;4.05%,96.0%.     

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.