Molecular Imprinted Polymers Prepared by Electropolymerization of Ni-(Protoporphyrin IX)

Abstract

The features of combining a chemically modified electrode (CME) with an artificial receptor system, prepared by imprinting electropolymerized [Ni

(Protoporphyrin IX) dimethyl ester] [Ni-(PPIX)] in the presence of nitrobenzene, were studied. The responses of the modified glassy carbon electrode towards template molecules were analyzed by cycling over the nitrobenzene reduction wave. The specific signal was much higher than the non-specific one which demonstrates the selectivity of such a system.

This approach has potential for preparation of selective polymeric films on the surface of different transducers.

     

Mechanistic study of the oxidation of -ascorbic acid by chloranil at the nitrobenzene water interface

The redox reaction between -ascorbic acid in water and chloranil in nitrobenzene has been studied by means of polarography with an ascending water electrode as well as cyclic voltammetry with a stationary interface. Through accurate measurement of the limiting currents, it has been suggested that the redox reaction should be a two-electron reaction rather than a one-electron reaction described previously. A spectrophotometric technique has also been used to observe that the redox reaction proceeds spontaneously under certain conditions even without electrochemical control. Based on these findings, it has been concluded that the present heterogeneous charge transfer reaction is the ion transfer of chloranil semiquinone radical, which is driven by the homogeneous electron transfer between ascorbic acid and chloranil in the aqueous phase.     

Additivity of theHammett reaction constants ion pairs effect in the polarographic reduction of nitrobenzene and 9,10-anthraquinone derivatives

An attempt has been made to estimate the effect of the subsequent ion pairs formation on the value of theHammett reaction constant measured polarographically. To this purpose, the reduction ofpara-substituted nitrobenzenes and 2-substituted 9,10-anthraquinones was studied at a dropping mercury electrode in N,N-dimethylformamide. The ion pairs reaction constant of substituted nitrobenzene radical anions with tetraethylammonium cations is equal to –1.49 V/ unit. The corresponding reaction constant for the semiquinone—Li⁺ series was estimated to be –0.90 V/ unit. The method of calculation was based on the additivity rule withinHammett's treatment.

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Zur Additivität derHammet'schen Reaktionskonstanten. Paar-Effekte bei der polarographischen Reduktion von Nitrobenzol und 9,10-Anthrachinonderivaten

Zusammenfassung Es wurde eine Abschätzung des Effekts der nachfolgenden Ionenpaarbildung auf den polarographisch bestimmten Wert derHammet'schen Reaktionskonstanten versucht. Dazu wurde die Reduktion vonpara-substituierten Nitrobenzolen und 2-substituierten 9,10-Anthrachinonen an der tropfenden Quecksilberelektrode in N,N-Dimethylformamid untersucht. Die Ionenpaar-Reaktionskonstanten von substituierten Nitrobenzol-Radikalanionen mit Tetraethylammoniumkationen ist gleich –1.49 V/-Einheiten. Die ents prechende Reaktionskonstante für die Semichinon-Li⁺ Serie wurde mit –0.9 V/-Einheiten abgeschätzt. Die Berechnungsmethode basiert auf der Additivitätsregel derHammet'schen Reaktionskonstanten.

     

贮氢合金用作硝基苯电解加氢的催化电极研究

贮氢合金用作硝基苯电解加氢的催化电极研究卢世刚，杨汉西，王长发（武汉大学化学系，武汉１３００７２）混合稀土贮氢合金是近年来发展起来的新型功能材料。在室温下它可以吸收比自身体积大几百倍的氢原子形成金属氢化物．这种金属氢化物可作为氢源提供高反应活性的氢原...     

One-pot preparation of azobenzenes from nitrobenzenes by the combination of an indium-catalyzed reductive coupling and a subsequent oxidation

We demonstrated how a reduction step with a reducing system comprised of In(OTf)₃ and Et₃SiH and a subsequent oxidation that occurred under an ambient (oxygen) atmosphere allowed the highly selective and catalytic conversion of aromatic nitro compounds into symmetrical or unsymmetrical azobenzene derivatives. This catalytic system displayed a tolerance for the functional groups on a benzene ring: an alkyl group, a halogen, an acetyl group, an ester, a nitrile group, an acetyl group, an ester moiety, and a sulfonamide group.     

固相萃取-毛细管气相色谱法测定生活饮用水中16种硝基苯类化合物

建立了生活饮用水中16种硝基苯类物质的固相萃取-毛细管气相色谱-电子捕获检测方法.实验优化了色谱柱、升温程序等色谱条件,并对影响固相萃取效果的主要因素(萃取小柱、洗脱剂和洗脱体积)进行了考察.水样中16种硝基苯类物质经Oasis HLB固相萃取柱吸附、正己烷-丙酮(3∶1,V/V)洗脱后,采用DB-1701毛细管气相色谱柱程序升温分离、ECD检测,在33 min内完成所有待测组分的测定.16种硝基苯类组分在各自的线性范围内相关系数r≥0.998,方法的检出限为0.01 ～0.77 μg/L(S/N=3),定量限为0.03 ～2.57 μg/L(S/N=10),日内精度和日间精度分别在1.0％ ～ 3.8％和2.3％～4.8％间,样品加标回收率为83.6％～ 111.8％,加标样品的RSD为1.2％ ～5.1％.应用本方法对50份水样进行了分析,结果表明,本方法准确、灵敏、快速,适用于水质的常规分析,可为水样中硝基苯类物质的污染评价提供技术支持.     

Preparation of phenothiazine bonded silica gel as sorbents of solid phase extraction and their application for determination of nitrobenzene compounds in environmental water by gas chromatography-mass spectrometry

In this paper, two phenothiazine bonded silica (PTZ-Si) sorbents were prepared and used as sorbents of solid-phase extraction (SPE) for the determination of nitrobenzene compounds in environmental water samples by gas chromatography-mass spectrometry (GC-MS). Different synthesis routes were proposed to obtain high bonded amount of PTZ on the surface of silica gel. PTZ molecule was derived to its amino or acyl chloride derivatives for reacting with isocyanate or amino silane coupling agent, which was further reacted with the surface silanol groups of silica gel to obtain the PTZ-Si sorbents. The resultant PTZ-Si sorbents were characterized by nitrogen sorption porosimetry (NSP), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to assure the successful bonding of PTZ on the surface of silica gel. Then the PTZ-Si sorbents were served as SPE sorbents for the enrichment of nitrobenzene compounds. Several parameters affecting the extraction performance were investigated. Under the optimized conditions, the proposed method was applied to the analysis of six nitrobenzene compounds in environmental water samples. Good linearities were obtained for all nitrobenzene compounds with R(2) larger than 0.9958. The limits of detection were found to be in the range of 0.06-0.3 ng/mL. The method recoveries of nitrobenzene compounds spiked in water samples were from 71.4% to 124.3%, with relative standard deviations (RSDs) less than 10.1%.     

气相色谱法分离和测定溶剂型木器涂料中正丁醇与苯系物

在气相色谱法测定溶剂型木器涂料中正丁醇及苯系物(包括苯、甲苯及二甲苯)时采用了VF-200MS型号的毛细管色谱柱。由于此型号的毛细管柱具有较强极性,不仅能达到正丁醇与苯系物之间的有效而满意的分离,而且还能使苯系物(包括苯、甲苯、乙苯、二甲苯)之间和二甲苯的同分异构体之间的有效分离。测定中采用正戊烷作内标和用火焰离子检测器检测。此方法的检出限(2S/N)在1.7~3.5 ng之间。用一含有正丁醇的硝基漆样品按所提出的方法进行多次重复测定,并在此样品的基础上加入各被测化合物的标准后进行测定,从而对方法的回收率和精密度作了测试,测得其回收率在87.8%~100.0%之间,测定值的相对标准偏差(n=6)均小于2.5%。     

Synthesis and Mesomorphic Characterisation of Chiral Homologues

Abstract

Chiral liquid crystals have attracted considerable interest as they exhibit a good variety of modulated phases. We have synthesised a homologous series viz., 4-(4^!-n-alkoxy benzoyloxy) benzylidene-4^!!?1-(s)-methyl propoxy anilines, incorporating a terminal chiral centre, inorder to obtain better understanding of the relationship between molecular structure and appearance of SmC* phase in the molecules. It is observed that, in the present series the lower members upto butyl are pure nematogens, while pentyl to hexadecyl derivatives exhibit classical smectic as well as nematic mesophases. An additional smectic C* phase is observed in the middle octyl to dodecyl homologues. The homologues have been characterised by IR, NMR and DSC. Their mesomorphic properties have been compared with structurally related homologous series.