高碘酸钾氧化酸性铬蓝K催化光度法测定痕量锰

研究了测定痕量锰的新催化光度法，在pH11.90的条件下，锰（Ⅱ）催化高碘酸钾氧化酸性铬蓝K的反应。测定锰的线性范围为0—8．0ng／mE，检出限为0．05ng／mL。用于饮用水中锰的测定，方法的回收率在94．3％-102．7％范围内，结果令人满意。     

煌焦油蓝-溴酸钠体系催化动力学光度法测定痕量甲醛

基于H2SO4介质中甲醛催化NaBrO3氧化煌焦油蓝的褪色反应，建立了测定痕量甲醛的催化动力学分析方法。探讨了该方法的反应机理，对其反应条件进行了研究。测定线性范围为0．16～2．00μg／mL，检出限为8ng／mL。方法已应用于海产品水发液中痕量甲醛的测定。     

催化荧光法测定痕量铜—Cu（Ⅱ）—藏红T—H2O2体系

本文研究了在氨性介质中,铜(Ⅱ)催化过氧化氢氧化藏红T褪色,使荧光减弱的指示反应。建立了催化荧光法测定痕量铜的新方法。铜量在0.1～2ng/mL范围内呈线性关系。应用于食品中痕量铜的测定,结果满意。     

阻抑次甲基蓝褪色反应动力学法测定痕量钒

在硫酸介质中,基于钒对次甲基蓝与溴酸钾和抗坏血酸的催化氧化还原反应的抑制作用,建立了高灵敏度测定痕量钒新的动力学分析方法。其检出限为3．5×10－11g／mL,线性范围0～10μg／L。方法可用于食物、药材及水中钒的测定,结果均较为满意。     

催化动力学光度法测定铜的研究

建立一种在氢氧化钠介质中．借铜催化过氧化氢氧化甲基百里酚蓝褪色反应测定微量铜。方法的检出限为0．056μg／25ml，线性范围为0．5～5．0μg／25ml。     

催化荧光光度法测定砷的研究

在硫酸介质中，痕量砷对碘酸钾与罗丹明6G的氧化还原反应有催化作用，使罗丹明6G的荧光减弱，据此建立了催化荧光法测定痕量砷的新方法。方法检出限为0.26ng/mL，测定范围4.12ng/mL-82.4ng/mL。已用于环境和生物样品测定。     

催化H2O2氧化2, 3, 4, 9-四氢-9-羟基-1, 10-蒽醌荧光猝灭法测定痕量砷

基于HCl介质中和α,α-联吡啶存在下,As(V)可催化H2O2氧化2,3,4,9-四氢-9-羟基-1,10-蒽醌(R)转化无荧光化合物,导致体系荧光急剧猝灭,据此建立了催化H2O2氧化R荧光猝灭法测定痕量砷的新方法.在最佳条件下,As(V)含量在0.004 0~0.400 0 ng/mL范围内与荧光光强度的△If值符合比尔定律,工作曲线的回归方程△If=11.94 233.7 CAs(V)(ng/mL),n=7,相关系数r=0.9994,检出限为6.2×10-13g As(V)/mL,n=11.对0.004 0和0.400 0 ng/mL As(V)分别进行11次的测定,其RSD为2.6%与3.8%.该方法重现性好、灵敏、准确,用于实际中砷含量的测定,结果满意.还报道了R的合成,并借助核磁共振谱、红外光谱及质谱等谱学方法确定了其结构.     

铜(Ⅱ)催化过氧化氢氧化5-Cl-PADAT褪色反应的动力学研究及其应用

在KH2PO4 NaOH介质中研究了铜(Ⅱ)催化H2O2氧化5 Cl PADAT的褪色反应,测定了反应动力学参数,并建立了测定痕量铜的新方法。本法检出限为6.25×10-11g mL,铜(Ⅱ)的质量浓度在0～2.24ng mL范围内与log(A0 A)呈良好的线性关系。该法已用于核桃、人发样中痕量铜的测定。     

双波长双指示剂催化光度法测定铜的研究

研究了在pH 4.0的HAc～NaAc缓冲介质中,利用痕量铜(Ⅱ)催化过氧化氢氧化罗丹明B和亚甲基蓝褪色的指示反应,通过测量540 nm和660 nm下,催化体系和非催化体系吸光度的变化,建立了双波长双指示剂催化动力学光度法测定痕量铜的新方法.方法的线性范围为0.00080～0.048μg/mL,检出限为4.0×10~(-11) g/mL.方法可用于水中铜的测定.     

阻抑动力学光度法测定痕量邻苯二酚

在pH8．0的KH2PO4-Na2HPO4缓冲介质中，Mn(Ⅱ)催化高碘酸钾氧化二甲酚橙的褪色反应，邻苯二酚可灵敏地阻抑。研究了该指示反应的动力学参数及阻抑反应的机理，建立了动力学光度法测定痕量邻苯二酚的新方法。方法检出限为12．3ng／mL，线性范围在0．5～5．0μg／25mL和6．0～11．0μg／25mL。采用分馏法用于污水中邻苯二酚的测定，结果满意。     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.