茚三酮缩7-氨基-8-羟基喹啉-5-磺酸催化荧光测定痕量钒(Ⅴ)及其催化反应机理

合成了新型席夫碱类试剂茚三酮缩7－氨基－8－羟基喹啉－5－磺酸，建立了该试剂催化荧光测定痕量钒（Ⅴ）的新体系，反应在盐酸体系中进行，其λex／λm为325／448（nm），钒（Ⅴ）的量在0～40．0μg／L、40.0～160．0μg／L呈良好线性关系，检测下限为1.7μg／L，方法用于水样痕量钒的测定，结果令人满意。此外，还详细探讨了反应机理和动力学方程。     

停流流动注射—动力学方法多组份同时测定的研究：铁（Ⅱ）,钛（Ⅲ）和…

依据诱导反应原理，提出了同时测定多组份的动力学方法，并以停流流动注射分析研究了Ｆｅ（Ⅱ），Ｔｉ（Ⅲ）及Ｖ（Ⅳ）诱导的Ｃｒ（Ⅵ）－Ｉ＾－反应体系，建立了铁，钛和钒同时测定的条件。对铁，钛和钒测定的线性范围分别为０－２．２μｇ／ｍｌ，０－３．１μｇ／ｍｌ及０－１．８μｇ／ｍｌ，检测限分别为０．０１２，０．０２０和０．０１８μｇ／ｍｌ。     

催化动力学光度法测定痕量钒（Ⅴ）的研究

本文研究了在酸性介质中痕量钒（Ⅴ）催化氯酸钾氧化变色酸及抗坏血酸体系的反应和动力学条件，建立了催化动力学光度法测定痕量钒（Ⅴ）的新方法。该方法的检出限为０．０８ｎｇ／ｍＬ Ｖ（Ⅴ），线性范围为０～０．３μｇ／２５ｍＬ Ｖ（Ⅴ）。将该方法用于水样及人发中痕量钒（Ⅴ）测定，结果令人满意。     

无机还原剂与光泽精化学发光反应的研究Ⅲ．钒（Ⅱ）－光泽精体系的化学发光反应

本文采用装有Ｊｏｎｅｓ柱的流动注射系统，研究了钒（Ⅱ）－光泽精体系的化学发光反应。在此基础上建立了痕量钒测定的新方法。方法的检出限３×１０￣（－１０）ｇ·ｍＬ￣（－１）；对于１．０×１０￣（－７）ｇ·ｍＬ￣（－１）钒标准溶液测定的相对标准偏差为２％（ｎ＝１１）；线性范围１．０×１０￣（－９）～９．０×１０￣（－５）ｇ·ｍＬ￣（－１），相关系数大于０．９９８０。该方法已用于水样中痕量钒的测定。对于反应机理，本文也进行了探讨。     

氯酸钾－二甲基黄－钒（Ⅴ）体系催化光度法测定痕量钒

本文研究了氯酸钾－二甲基黄－钒（Ⅴ）体系催化光度法测定痕量钒的条件及应用。钒含量在０～６０ｎｇ／１０ｍＬ范围内与ｌｇ（Ａ＿０／Ａ）有良好的线性关系，检出限１．０×１０￣（－１１）ｇ／ｍＬ。方法简便快速，应用于水及食品中痕量钒测定，结果满意。     

吖啶橙催化荧光法测定痕量钒

研究了在酸性介质中柠檬酸存在下,痕量钒（Ｖ）催化溴酸钾氧化吖啶橙退色及其动力学条件,建立了催化荧光法测定痕量钒（Ｖ）的新方法。钒（Ｖ）的线性范围为 ０．２～２．８ μｇ／Ｌ,检出限为 ５．８× １０－８ｇ／Ｌ。３０多种离子基本不干扰测定,将方法用于矿泉水,枸杞和人发样品中钒（Ｖ）的含量的测定,结果满意。此外,还对反应机理进行了初步探讨。     

树脂相吸光光度法测定痕量钒

提出了ＤＦＢ－Ｖ（Ⅴ）体系树脂相光度法测定痕量钒的方法，灵敏度高，选择性好，除Ｆｅ（Ⅲ）外其它离子基本无明显干扰，测定范围为０．２－４５ｎｇ．ｍｌ＾－１。实测了天然不中钒，结果令人满意。     

钒（V）—桑色素—溴化十六烷基三甲铵胶束增敏荧光光度法的研究和应用

研究了在pH2．5的HCI－NaAc介质中,溴化十六烷基三甲铵（CTMAB）对桑色素（morin)和钒（V）配合物荧光的增敏作用,建立了利用钒（V－morion-CTMAB胶束增敏荧光反应测定痕量钒的荧光光度新方法。方法的检出限为0．92μg/L,荧光强度与钒的含量在0．010－6．0μg/10mL范围内呈线性关系,配合物中钒（V）与桑色素的组成比为：V（V）：morin=1:1。方法可应用于天然水和食品中微量钒的测定。     

铁(Ⅲ)-高碘酸钾-过氧化氢-变色酸2R催化动力学光度法测定痕量铁的研究

研究了测定铁的一种新指示反应，在稀硫酸介质中，痕量铁（Ⅲ）对高碘酸钾与过氧化氢协同氧化变色酸２Ｒ的褪色反应具有强烈催化作用，其反应的动力学条件，表观活化能Ｅ′＝１８９．８１ｋＪ／ｍｏｌ，表观反应速率常数Ｋ＝５．６７×１０－４／ｓ，半衰期ｔ１／２＝２０．３７ｍｉｎ。反应温度为９０℃，试验表明ｌｇＡ０／Ａ与Ｆｅ（Ⅲ）的浓度在３０～１００ｎｇ／２５ｍＬ范围内符合Ｂｅｒ定律，建立了催化动力学光度法测定痕量铁的新方法。方法的检测限为１．２５×１０－９ｇ／Ｌ，加入回收率在９７．０％～１０２％，应用于测定西洋参口服液、美国花旗参茶和天然矿泉水中铁的含量结果满意。     

茚三酮缩7—氨基—8—羟基喹啉—5—磺酸催化荧光测定痕量钒（Ⅴ）及其…

合成了新型席夫碱类试剂茚三酮缩７－氨基－８－羟基喹啉－５－磺酸，建立了该剂催化荧光测定痕量钒的 新体系，反应在盐酸体系中进行，其λｅｘ／λｅｍ为３２５／４４８（ｎｍ），钒（Ⅴ）的量在０－４０．０μｇ／Ｌ、４０．０－１６０．０μｇ／Ｌ呈良好线性关系，检测下限为１．７μｇ／Ｌ，方法用于水样痕量钒的测定，结果令人 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.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.