吸附溶出催化伏安法测定人参中的锗

本文提出了利用吸附溶出催化伏安法测定人参中锗的方法。最佳体系为:2.5×10~(-2)mol/LH_2O_2、2.0×10~(-2)mol/L邻苯二酚、2.0×10~(-3)mol/L H_2SO_4。线性范围为2.0×10~(-9)～2.0×10~(-7)mol/L。当富集时间为4 min时,最低检测浓度为4.0×10~(-10)mol/L。此法己成功地应用于测定人参中的锗。     

导数示波极谱法测定大气和水中痕量硫化物

本文提出以导数示波极谱法直接测定各种水质和大气中痕量硫化物,底液为0.032mol/LEDTA—0.10mol/L NaOH—0.040mol/L抗坏血酸。在—0.70V(V_·SCE)处,获得一灵敏的导数峰电流。硫化物浓度在9.38×10~(-9)～5.16×10~(-4)mol/L之间与峰电流有线性关系。检测限为3.12×10~(-9)mol/L。用本方法分别测定大气中的H_2S和水中的硫化物,获得满意结果。     

三维荧光光谱法连续测定苯胺、二苯胺和N-甲基苯胺

本文比较了苯胺、二苯胺、N-甲基苯胺的二维荧光光谱和三维荧光光谱。提出了同时测定苯胺,二苯胺和N甲基苯胺的分析方法,它们的浓度分别在2.0×10~(-7)～5.0×10~(-6)mol/L,9.0×10~(-8)～7.4×10~(-6)mol/L,1.3×10~(-7)～2.0×10~(-8)mol/L范围内有良好的线性关系,检出限为1.0×10~(-7)mol/L,8.0×10~(-9)mol/L,1.0×10~(-7)mol/L.相对标准偏差分别为5％,7％,7％.此方法用于混合样品和工业废水的分析,获得较满意的结果.     

过氧化物模拟酶在介体型生物传感器方面应用初探

meso-四(4-磺基苯)卟啉锰(Ⅲ)作为过氧化物模拟酶可催化H_2O_2与K_4Fe(CN)_6反应。电流响应与H_2O_2浓度在3.0×10~(-4)～1.0×10~(-3)mol/L范围内呈线性关系。重现性和回收率良好。抗坏血酸和DL-半胱氨酸干扰严重。     

痕量硫代硫酸根的示波极谱法测定

在Fe~(2+)-NO_2~--VC体系中,在单扫示波极谱仪上,有一很灵敏的S_2O_3~(2-)阴极波,峰电位为-0.37伏(vs. SCE)。阴极导数波高与S_2O_3~(2-)浓度在6×10~(-8)mol/L—1×10~(-6)mol/L之间成线性关系,出限为5×10~(-8)mol/L。该法可用于环境水中痕量S_2O_3~(2-)的测定。该波具有吸附性质,系三元络合物Fe·S_2O_3-No催化溶解氧还原所致。     

铜-铋试剂配合物吸附波的研究

本文提出极谱测定微量铜的铜-铋试剂新体系。在0.064mol/L KOH,0.16mol/L NH_3·H_2O,1.28×10~(-4)mol/L铋试剂溶液中,铜(Ⅱ)-铋试剂配合物在单扫示波极谱上有一灵敏的配合物吸附波。铜浓度在8×10~(-9)～8×10~(-7)g/ml范围内与导数波高成良好的线性关系。将该休系应用于铝合金中痕量铜的测定,结果满意。     

过氧化物酶模拟酶催化荧光反应的研究(Ⅰ)——MnTPPS_4-HVA-H_2O_2体系

首次研究了meso-四(4-磺基苯)卟啉和锰的络合物(MnTPPS_4)作为过氧化物酶模拟酶对高香草酸(HVA)和H_2O_2荧光反应的催化作用,拟订了用模拟酶测定痕量H_2O_2和葡萄糖的荧光测定方法,并对模拟酶和天然酶的性能进行了比较。用MnTPPS_4测定H_2O_2和葡萄糖的灵敏度分别可以达到8.5×10~(-8)mol/L的H_2O_2和0.5μgmL~(-1)的葡萄糖。     

一种基于形成杂多核络合物的荧光增敏效应的研究 Ⅲ.锰(Ⅱ)、钴(Ⅱ)的混合荧光增敏及其连续测定

本文研究了Mn~(2+)和Co~(2+)对7-(8-羟基-3,6-二磺基萘偶氮)-8-羟基喹啉-5-磺酸-硼砂反应体系的混合荧光增敏作用。实验条件下,荧光增敏强度满足线性加和关系的范围是:Mn~(2+)浓度0～2.9×10~(-7)mol/L;Co~(2+)浓度0～8.8×10~(-7)mol/L;总浓度不超过1.0×10~(-6)mol/L。检出限量为Mn~(2+)4.5×10~(-9)mol/L和Co~(2+)1.4×10~(-8)mol/L。实现了Mn~(2+)和Co~(2+)的连续测定。     

溶出伏安法同时测定水中痕量铀和镍

本文报道了同时测定钴和镍的一种方法.在 0.01mol/L NH_3·H_2O-0.01mol/LNH_4Cl-3.0×10~(-5)mol/L安息香缩氨基硫脲(BTSC)溶液中,钴(Ⅱ)和镍(Ⅱ)均产生非常灵敏的还原波,其峰电位分别是:-0.94和-0.75V(vs.SCE),峰电流与钴和镍的浓度分别在2.0×10~(-8)~1.0×10~(-6)和1.0×10~(-8)~8.0×10~(-7)mol/L范围内成直线关系,该方法用于测定水中痕量钴和镍,相对标准偏差分别为1.4~2.0%和2.1~2.5%,回收率分别在98.0%~101.8%和97.9%~102.1%之间.     

络合吸附波测定微量硅的研究

建立了硅锑钼三元杂多酸体系导数极谱测定微量硅的新方法。在0.6mol/L硫酸-20％乙醇介质中,于55℃时,硅(Ⅳ)、锑(Ⅲ)和钼(Ⅷ)形成具有电活性的硅锑钼三元杂多酸;在0.3 mol/L硫酸-10％乙醇介质中,于-0.47V(vs. SCE)处产生一灵敏的还原峰,其二阶导数电流峰高与硅的浓度在6.8×10~(-9)～7.4×10~(-7)mol/L范围内呈线性关系,检出限为4.3×10~(-9)mol/L,应用于水样及矿石中硅的测定,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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.