Summary. A variety of 1,3-diyne compounds are prepared in a solvent-free reaction on KF/alumina in the presence of catalytic amounts
of Cu(OAc)2·H2O with up to 96% yields at room temperature. 相似文献
Summary. The oxidation of arenes and sulfides by potassium permanganate was accomplished in good yields under solvent free and heterogeneous
conditions when manganese(II) sulfate is used as a solid support. After extraction of the organic products, the inorganic
products can be reoxidized to permanganate. This result is important because it provides an approach to oxidation reactions
that is, in theory, infinitely sustainable. 相似文献
Summary. The palladium-catalyzed coupling reaction of aryl bromides with various amines under microwave irradiation was studied using
PdCl2 [P(o-tolyl)3]2 which gave various aryl amines in good yields. The reactions were carried out under normal atmospheric conditions.
Received September 3, 2001. Accepted October 10, 2001 相似文献
Dye decolorization is currently measured by the reduction of dye absorption, based on its linear optical properties in solution. However, this method is not suitable for high dye concentrations with linear attributes in the absorption spectra. In this work, nonlinear optical properties are used to study dye decolorization of Crocin and Rhodamine B treated with a bacterial laccase. For this purpose, the Z-scan was used to obtain the nonlinear refractive indices and nonlinear absorption coefficient of Rhodamine B and Crocin in the presence and absence of the bacterial laccase enzyme. The results showed that nonlinear optical properties could be used to study dye decolorization in solutions. 相似文献
An organic‐inorganic material (NH4)2(MimAM)40[Mo132O372(CH3COO)30(H2O)72] have been synthesized by reacting [(NH4)42[MoVI72 MoV60O372(CH3COO)30(H2O)72] with the ionic liquid 3‐Aminoethyl‐1‐methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H2O2 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n‐heptane reached to 98.3% yield at 40 °C using 2.5 mmol H2O2 and 100 mg of (NH4)2(MimAM)40[Mo132O372(CH3COO)30(H2O)72] after 90 min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6‐DMDBT (4,6‐dimethyl‐dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6‐dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity. 相似文献
Two novel plasma chemistries, BI3and BBr3, have been employed for dry etching of LaCaMnO3thin films. For both mixtures there is some chemical enhancement of etch rates at low halide compositions in the discharge, and the rates are a strong function of ion/neutral ratio. Maximum rates are obtained at ratios near 0.02. Etch yields are typically low (<0.3) under inductively-coupled plasma (CICP) conditions. Smoothdsurface morphologies are obtained over a wide range of conditions, with high-fidelity pattern transfer using SiO2or SiNxmasks.相似文献
Textile is one of the main components in the municipal waste which is to be diverted from landfill for material and energy recovery. As an initial investigation for energy recovery from textile residues, the combustion of cotton fabrics with a minor fraction of polyester was investigated in a packed bed combustor for air flow rates ranging from 117 to 1638 kg/m2 h (0.027–0.371 m/s). Tests were also carried out in order to evaluate the co-combustion of textile residues with two segregated waste materials: waste wood and cardboard.
Textile residues showed different combustion characteristics when compared to typical waste materials at low air flow rates below 819 kg/m2 h (0.186 m/s). The ignition front propagated fast along the air channels randomly formed between packed textile particles while leaving a large amount of unignited material above. This resulted in irregular behaviour of the temperature profile, ignition rate and the percentage of weight loss in the ignition propagation stage. A slow smouldering burn-out stage followed the ignition propagation stage. At air flow rates of 1200–1600 kg/m2 h (0.272–0.363 m/s), the bed had a maximum burning rate of about 240 kg/m2 h consuming most of the combustibles in the ignition propagation stage. More uniform combustion with an increased burning rate was achieved when textile residues were co-burned with cardboard that had a similar bulk density. 相似文献
Cytidine triphosphate synthetase (CTPS) catalyzes the formation of cytidine triphosphate from glutamine, uridine-5'-triphosphate (UTP), and adenosine-5'-triphosphate. Inhibitors of CTPS are of interest because of their potential as therapeutic agents. One approach to potent enzyme inhibitors is to use analogues of high energy intermediates formed during the reaction. The CTPS reaction proceeds via the high energy intermediate UTP-4-phosphate (UTP-4-P). Four novel analogues of uridine-4-phosphate (U-4-P) and 3-deazauridine-4-phosphate (3-deazaU-4-P) were synthesized in which the labile phosphate ester oxygen was replaced with a methylene and difluoromethylene group. The methylene analogue of U-4-P, compound 1, was prepared by a reaction of the sodium salt of tert-butyl diethylphosphonoacetate with protected, 4-O-activated uridine followed by acetate deprotection and decarboxylation. It was found that this compound undergoes relatively facile dephosphonylation presumably via a metaphosphate intermediate. The difluoromethylene derivative, compound 2, was prepared by electrophilic fluorination of protected 1. This compound was stable and did not undergo dephosphonylation. Synthesis of the methylene analogue of 3-deazaU-4-P, compound 3, was achieved by ribosylation of protected 4-(phosphonomethyl)-2-hydroxypyridine. Electrophilic fluorination was also employed in the preparation of protected 4-(phosphonodifluoromethyl)-2-hydroxypyridine which was used as the key building block in the synthesis of difluoro derivative 4. These compounds represent the first examples of a nucleoside in which the base has been chemically modified with a methylene or difluormethylenephosphonate group. 相似文献