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81.
O. A. Kholdeeva R. I. Maksimovskaya G. M. Maksimov K. I. Zamaraev 《Reaction Kinetics and Catalysis Letters》1998,63(1):95-102
Alkylammonium salts of Ti(IV)-substituted heteropolytungstate, PW11TiO
10
5−
, catalyze the oxidation of methyl phenyl sulfide with hydrogen peroxide. The yield of the corresponding sulfoxide and sulfone
is practically quantitative. A31P NMR study confirms the formation and reactivity of the PW11O39TiO
2
5−
peroxo complex in organic media. 相似文献
82.
刘晓庚 《理化检验(化学分册)》2006,42(10):809-812
联合应用BPO与KIO3(在KI存在下)的倍增反应和光度滴定数据的二阶导数法处理,使面粉中微量BPO测定的灵敏度较常规碘量法提高了200倍,方法的检出限可达0.1 mg.L-1。在面粉实样分析中,测定结果的RSD值在1.3%~2.8%之间,加标回收率在98.6%~102.2%之间。提出的方法所得测定结果与国标法(GB/T 18415-2001)所得结果一致。 相似文献
83.
Sodium tetrafluoroborate (NaBF4) is found to catalyze the three component condensation of an aldehyde, 1,3‐dicarbonyl compound and urea or thiourea to afford the corresponding 3,4‐dihydropyrimidin‐2(1 H)‐ones and thiones in high yields. This method is very useful for the synthesis of a wide range of 3,4‐dihydropyrimidin‐2(1 H)‐ones and thiones from aromatic, heterocyclic, α,β‐unsaturated aldehydes and aliphatic aldehydes. 相似文献
84.
Guangdong Zhou Zhanlin Xu Xiaohong Guo Hong Zhuang Yanan Li Xueju Lü Tiexin Cheng Wenxing Li Kaiji Zhen 《Reaction Kinetics and Catalysis Letters》2005,85(1):57-64
Summary The oxidation of hexanol in the presence of the Keggin-type heteropoly compounds (HPCs) H3PMonW12-nO40 (denoted as PMonW12-n, n=0,1) and Na5PW11ZO39 (denoted as PW11Z, Z = Mn, Fe, Co, Ni, Cu and Zn) was carried out to produce hexanal and hexanoic acid. The reaction was conducted in tert-butanol (t-BuOH), using cetylpyridinium bromide (CPB) salts of HPA and 15% aqueous H2O2 as oxidant under mild condition. The PMoW11 catalyst showed higher hexanol conversion of 25%, the lowest selectivity to hexanal of 64.4% and an efficient utilization of H2O2 of 34%. Over the transition metal substituted PW11Z catalysts decomposition of H2O2 was rapid. For these PW11Z catalysts, the efficient utilization of H2O2 decreased to 9% or even lower. By means of IR, UV-visible and GC-MS techniques the catalysts were characterized. 相似文献
85.
Poly(N‐vinyl‐2‐pyrrolidone‐crotonic acid) [P(VP/CrA)] hydrogels were prepared by irradiating the ternary mixture of VP/CrA and crosslinking agent ethylene glycol dimethacrylate (EGDMA) in water by γ rays at ambient temperature. Differential scanning calorimetry and thermogravimetric analysis were performed to evaluate the thermal properties of ionized networks and to establish if they showed thermal differences that could be related to the CrA content in the gel system. The volume swelling ratio of P(VP/CrA) hydrogels were investigated as a function of the pH in the immersing solution. The volume swelling ratio of these hydrogels increased with an increase in pH and a decrease CrA content in the hydrogel. The volume swelling ratio of the hydrogels was also evaluated using an equation, based on the Flory—Huggins thermodynamic theory, the phantom network theory of James–Guth and Donnan theory of swelling of weakly charged ionic gels for determination of the molecular weight between crosslinks and the polymer–solvent interaction parameter (χ). Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
86.
Robert Franzén 《高等学校化学研究》2006,22(5):602-605
IntroductionAqueous hydrogen peroxide is considered to be a“green”oxidant with a high oxidation efficiency due toits low molecular weight,cleanness in the oxidationprocess in which only harmless water is produced,lowcost of production and safe transport… 相似文献
87.
《Electroanalysis》2006,18(3):259-266
In this paper, a new strategy for constructing a mediator‐type amperometric hydrogen peroxide (H2O2) microbiosensor was described. An electropolymerized thionine film (PTH) was deposited directly onto a gold electrode surface. The resulting redox film was extremely thin, adhered well onto a substrate (electrode), and had a highly cross‐linked network structure. Consequently, horseradish peroxidase (HRP) was successfully immobilized on nanometer‐sized Au colloids, which were supported by thiol‐tailed groups of 11‐mercaptoundecanoic acid (11‐MUA) monolayer covalently bound onto PTH film. With the aid of the PTH mediator, HRP‐labeled Au colloids microbiosensor displayed excellent electrocatalytical response to the reduction of H2O2. This matrix showed a biocompatible microenvironment for retaining the native activity of the covalent HRP and a very low mass transport barrier to the substrate, which provided a fast amperometric response to H2O2. The proposed H2O2 microbiosensor exhibited linear range of 3.5 μM–0.7 mM with a detection limit of 0.05 μM (S/N=3). The response showed a Michaelis‐Menten behavior at larger H2O2 concentrations. The KMapp value for the biosensors based on 24 nm Au colloids was found to be 47 μM, which demonstrated that HRP immobilized on Au colloids exhibited a high affinity to H2O2 with no loss of enzymatic activity. This microbiosensor possessed good analytical performance and storage stability. 相似文献
88.
In this paper, the levels and the torsional microstates of hydrogen peroxide are determined from fully optimized ab initio calculations using a nuclear model in one dimension. Calculations have been performed at the MP2 level with the 6-311 G(2df,2pd), 6-31 1+G(2df,2pd), cc-pVTZ and AUG-cc-pVTZ basis sets including polarization orbitals and diffuse functions. The most stable conformation, calculated with the MP2/AUG-cc-pVTZ approach, is a trans–gauche conformer lying at 67.5° from the trans structure. By using the same level of calculations, the heights of the trans and cis barriers have been determined to be 386.5 and 2643.8 cm−1 in a good agreement with the experimental data. The variational torsional levels split into four components by the tunnelling effect of the barriers. The splitting of the fundamental level caused by the trans barrier has been found to be 11.8683 cm−1, whereas the splitting caused by the cis barrier is insignificant under n=2. Current ab initio energies confirm the experimental assignments and verify the separability of the torsion from the rest of the vibrations. However, the experimental relation of dependence on the torsion of the rotational constants cannot be reproduced in one-dimension and depends on several additional vibrational effects. 相似文献
89.
Xiaofei Han Run Liu Zhude Xu Weixiang Chen Yifan Zheng 《Electrochemistry communications》2005,7(12):1195-1198
Nanocrystalline cadmium peroxide thin film has been electrodeposited on indium doped tin oxide glass substrate from aqueous solution at room temperature. The grain size of the nanocrystals of the film is estimated from XRD and is about 14 nm. The deposits are decomposed at 228 °C by formation of CdO, releasing plentiful heat at same time. The band-gap of the nanocrystalline CdO film made from decomposition of electrodeposited CdO2 is around 2.4 eV. 相似文献
90.
Fourier transform Raman spectra of eight mixtures of four organic solids, namely dicyandiamide, melamine, acetamide and urea were measured. Matrices formed from these spectra were first subjected to singular value decomposition to obtain the right singular vectors. The right singular vectors were then subjected to blind source separation using band-target entropy minimization (BTEM), thus no a priori information (i.e. involving the nature of the components present, their spectra, nor their concentrations) was included in the analysis. The recovered pure component spectra are of exceptionally high quality and are consistent with pure reference spectra. Various empirical and statistical tests, such as the Euclidean norm and target transform factor analysis, were employed to assess the quality of the recovered spectra. The present results indicate the applicability of combined Raman and BTEM analysis for solid mixtures. 相似文献