铟-8-氨基喹啉络合吸附波的研究

在0.04Mol/L HAc-0.36Mol/L NaAc(pH5.7)和3.5×10~(-4)Mol/L 8-氨基喹啉(8-Aminoquinoline)溶液中,用单扫示波极谱法可得到In(Ⅲ)-8-氨基喹啉络合吸附波,峰电位在-0.78V处。其导数峰高与铟在5.0×10~(-8)-4.0×10~(-6)Mol/L范围内的浓度呈线性关系,最低检出限为2.0×10~(-8)Mol/L。研究确定该波为1∶1铟-8-氨基喹啉络合物的吸附波。测定了几种地球化学标准样品中的锢,结果满意。     

In(Ⅲ) -NCP体系配位吸附波研究及应用

在0.15 mol/L HAc-NaAc(pH 3.2)介质中,In(Ⅲ)-NCP(2,9-二甲基邻菲咯啉)配合物在2.5次微分极谱图上产生良好的吸附还原波.其峰电位为-0.40 V,峰电流与In(Ⅲ)浓度在4.0×10-8～2.0×10-6 mol/L范围内呈良好的线性关系,检出限为8.0×10-9 mol/L.应用该法测定了氢氧化铝和陶瓷颜料中的微量铟,结果满意.研究了配合物的组成、极谱波的性质及其机理.     

铟(Ⅲ)-2-巯基苯骈噻唑-7-碘-8-羟基喹啉-5-磺酸三元络合物吸附波研究

在HCl-NaAc介质(pH 2.5)中,用单扫示波极谱法可获得高灵敏的In(Ⅲ)-2-疏基苯骈噻唑(MBT)-7-碘-8-羟基喹啉-5-磺酸(Ferron)三元络合物吸附波.峰电位在—0.64V(vs.SCE),峰电流与铟浓度在7.0×10~(-10)mol/L～8.8×10~(-7)mol/L之间呈线性关系.检出限可达3.0×10~(-10)mol/L.测得电活性络合物的组成为In(Ⅲ):MBT:Ferron=1:1:1.研究了极谱波的性质和机理.本法选择性较好,用于工业废水和地下水中痕量铟的测定,结果满意.     

铟—檞皮素极谱络合吸附波测定锌盐中的痕量铟

在pH5的醋酸盐缓冲底液中,可获得灵敏的铟(Ⅲ)—檞皮素的络合吸附波。铟浓度由1.O×10~(-9)—1.0×10~(-6)mol/L与其二阶导数波峰高有正比关系,检出限为5.0×10~(-10)mol/L,用于测定了试剂硫酸锌中的痕量铟,测得电活性络合物的组成为:In(Ⅲ):檞皮素=1:2,还讨论了络合物在汞电极上的吸附行为。     

铟-二甲酚橙络合吸附波的研究

铟(Ⅲ)在0.03mol/l邻苯二甲酸氢钾(KHP)、5×10~(-6)mol/l二甲酚橙(XO)溶液(pH3.9)中,出现一良好的示波极谱图,峰电位E_p=-0.68V(vs.SCE),其峰电流与铟的浓度在1.0×10~(-7)～3.0×10~(-6)mol/l范围内成线性关系,检测下限为5.0×10~(-8)mol/l。用等摩尔连续变化法确定络合物的络合比为In(Ⅲ):XO=1:1。用循环伏安法等电化学手段研究极谱波的性质及其反应机理。并测定了不同铟浓度时体系的吸附量。体系的吸附符合Frumkin吸附等温式,吸附系数β=4.3×10~5,吸引因数α=-1.75。实验表明,该波属于络合吸附波。     

铋-N-苯甲酰苯胲络合吸附波的研究

在pH5.6的0.2mol/L NH_4Ac-3×10~(14)mol/L N-苯甲酰苯胲(N-BPHA)底液中,用单扫示波极谱法可得到Bi(Ⅲ)的络合物吸附波,峰电位-0.33V(vs.SCE)左右。导数峰高与铋的浓度在5.0×10~(-8)～4.0×10~(-6)mol/L的范围内呈线性关系,检出限为2.0×10~(-8)mol/L。实验表明,该极谱峰属于络合物吸附波,测定其络合比为Bi(Ⅲ):N-BPHA=1:3。测定了该体系的吸附量;Bi(Ⅲ)-N-BPHA络合物在悬汞电极上的吸附符合Frumkin等温式,测得吸附系数β=2.87×10~5,吸引因子α=0.984。用于矿石中微量铋的测定。     

铟(Ⅲ)-芦丁极谱络合吸附波的研究

在pH6.0的乙酸盐缓冲底液中,用单扫极谱法可获得高灵敏度的铟(Ⅲ)-芦丁的络合吸附波,其检测下限达3.0×10~(-10)mol/L。成功地用于纯金属锌中10~(-5)％铟的测定。测得吸附电活性络合物的组成为:In(Ⅲ):芦丁=1∶2,条件稳定常数为1.8×10~(10)。电极反应是吸附络合物中的In(Ⅲ)还原为In(Hg)。测得电极反应的转移系数α=0.51,表面电化学反应的标准速率常数k_s=0.43/s     

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.     

Fe(Ⅲ)-8-羟基喹啉极谱络合吸附波的研究

以8-羟基喹啉作为络合剂,用单扫描极谱仪对微量Fe(Ⅲ)的络合吸附波进行了研究。8-羟基喹啉用量为2×10~(-3)mol/L时,用氢氧化钾溶液调节pH值至碱性条件(pH约为12.0),于-0.37V(vs. SCE)处,有一灵敏的阴极波。Fe(Ⅲ)浓度在2.1×10~(-8)～2.6×10~(-6)mol/L范围内与一阶导数波峰高成线性关系。该法可用于准确测定样品中痕量Fe(Ⅲ)。     

锑(Ⅲ)-5-Br-PADAP极谱络合吸附波研究

在0.20mol/L甲酸盐缓冲溶液(pH3.8)中,Sb(Ⅲ)-5-Br-PADAP络合物在单扫示波极谱仪上产生一良好的极谱波,峰电位-0.53V(vs.SCE),峰电流与锑浓度在4.1×10~(-8)～8.2×10~(-6)mol/L范围内呈线性关系。实验表明,该波属于络合吸附波。方法已应用于铜合金中锑的测定。     

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%.     

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.     

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.     

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.     

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.