Capillary electrophoretic determination of lignin degradation products obtained by permanganate oxidation

A new capillary electrophoretic (CE) technique was developed for the separation of lignin degradation products after permanganate oxidation, yielding information about quality and quantity of various linkages in the lignin molecule. This CE method is a promising alternative to existing gas chromatographic (GC) methods. An advantage in comparison with GC is the short separation time and the fact that the oxidation products (aromatic acids) can be analyzed without derivatization. The selectivity and sensitivity of CE combined with UV detection is adequate and makes it suited for fast routine characterization of lignins. If necessary, the CE method can be coupled with electrospray ionization mass spectrometry in order to make a clear assignment of the peaks.     

XPS study of interactions between linear carbon chains and colloidal Au nanoparticles

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烯丙位氧化的几种方法

综述了近年来烯丙位氧化的研究进展，详细讨论了过渡金属及其络合物、硒化 合物在烯丙位氧化中的应用，并简述了丁基锂方法、固相催化方法、生物氧化方法 和次氯酸钠氧化方法在烯丙位氧化中的应用．     

漆树漆酶的催化氧化作用——Ⅳ.二茂铁及其衍生物的酶促氧化

In phosphate buffer-diethylene glycol monobutyl ether(DGBE), the oxidations of ferrocene and 15 derivatives were investigated in the presence of Rhus vernicifera laccase. The results showed that ferrocene and 11 derivatives can be oxidized. The mechanism of Laccase catalyzed oxidation of ferrocene was put forward.     

RuO2 electrode surface effects in electrocatalytic oxidation of glucose

We have studied the electrocatalytic activity of RuO₂-PVC film electrodes, fabricated using RuO₂ powders prepared at five different temperatures, viz., 300, 400, 500, 600 and 700°C, for the oxidation of glucose in high alkaline media, 1 to 3 M NaOH. The RuO₂-PVC film electrodes have been first characterized in 1 to 3 M NaOH solution by cyclic voltammetry (CV) and rotating disc electrode (RDE) techniques in a wide potential range −1,100 to 450 mV (SCE), and three redox pairs representing Ru(IV)/Ru(III), Ru(VI)/Ru(IV) and Ru(VII)/Ru(VI) transitions have been identified. The voltammetric peaks at low sweep rates have been analyzed using surface activity theory formulated for interacting electroactive adsorption sites, and interaction terms have been evaluated. The total voltammetric surface charges have been analyzed as per Trassatti’s formalism with respect to their dependence on potential sweep rate, and charges associated with less accessible and more accessible surface sites have been calculated. For glucose oxidation, the results have indicated that RuO₂ (700°C)-PVC electrode shows two oxidation peaks in contrast to RuO₂ (300°C)-PVC electrode. Also, RuO₂ (700°C)-PVC electrode exhibits higher intrinsic electrocatalytic activity than the 300°C electrode, although the former possesses lower electrochemically active surface area. Additionally, kinetic analyses made from RDE results with reference to Michealis–Menten (MM) enzyme catalysis has shown that RuO₂ (700°C) electrode possesses extended glucose-sensing range in terms of MM kinetic constant, K _M , compared to other electrodes. Possible reasons for such differences in the behavior of the electrodes of different temperatures towards glucose oxidation are identified from studies on oxidation of glucose in solutions of different pH, oxidation of different glucose derivatives, and also from physicochemical results from BET, XRD, SEM, DTGA, XPS analysis of RuO₂ powder samples.     

Dynamic study of photosensitized one-electron oxidation of polyG by menadione

Quinones including menadione are ubiquitous in nature. They play important roles in aerobic respira- tion and photosynthesis[1,2]. In addition, exogenous quinones are used as antibiotics and anticancer drugs. Their function is closely related to their red…     

One-pot synthesis of phenol and cyclohexanone from cyclohexylbenzene catalyzed by N-hydroxyphthalimide (NHPI)

Synthesis of phenol and cyclohexanone in one pot was examined by means of the NHPI-catalyzed aerobic oxidation of cyclohexylbenzene. The aerobic oxidation of cyclohexylbenzene catalyzed by NHPI followed by treatment with sulfuric acid afforded phenol and cyclohexanone in good selectivities. Thus, the reaction of cyclohexylbenzene under atmospheric dioxygen (1 atm) by NHPI at 100 °C for 3 h followed by treatment with 0.3 M sulfuric acid at room temperature for 2 h resulted in phenol and cyclohexanone in 96 and 91% selectivity, respectively, at 25% conversion. This method was successfully extended to the one-pot synthesis of 4-hydroxyacetophenone and cyclohexanone.     

Redox behavior of V/MgO catalyst in H2S wet oxidation at room temperature

The room temperature wet catalytic oxidation was conducted in a batch reactor with V/MgO catalyst. The XRD study of the catalyst used indicated that V/MgO could not only oxidize H2S to sulfur selectively, but also prevent the sulfidation of metal oxide effectively at the room temperature. The XPS study indicated that the H2S oxidation with V/MgO could proceed by a redox mechanism (V⁵⁺↔ V⁴⁺) and that V³⁺ formation (V⁴⁺→ V³⁺), was responsible for the deactivation of V/MgO. This revised version was published online in June 2006 with corrections to the Cover Date.     

A Novel Environmentally Benign Method for the Selective Oxidation of Alcohols to Aldehydes and Ketones

In the presence of [Ru(terpyridine)(2,6‐pyridinedicarboxylate)], aliphatic and benzylic alcohols are oxidized to the corresponding aldehydes or ketones with high selectivity by using hydrogen peroxide as the oxidant. There is no need for the addition of co‐catalysts or organic solvents. By applying an optimized reaction protocol, high catalyst productivity (turnover number>10 000) and activity (turnover frequency up to 14 800 h^?1) has been achieved.     

CO2部分氧化乙烷制乙烯Pd—Cu／MoO3—SiO2催化剂的研究

用化学吸附－红外光谱、化学吸附－程序升温脱附（ＴＰＤ）和微型反应技术研究了Ｐｄ－Ｃｕ／ＭｏＯ３－ＳｉＯ２（ＭｏＳＯ）催化剂对ＣＯ２和乙烷的吸附活化和部分氧化反应性能．结果表明，乙烷以Ｃ—Ｈ键中的Ｈ吸附于ＭｏＳＯ载体表面ＭｏＯ键的端基氧上；Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂对ＣＯ２有良好的化学吸附活化性能，ＣＯ２的吸附除有线式吸附态和剪式吸附态外，还有一种新的卧式吸附态；Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂的晶格氧参与了化学反应．探讨了在Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂上ＣＯ２的部分氧化乙烷反应机理