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141.
142.
《Comptes Rendus Chimie》2016,19(10):1203-1225
This review paper presents an overview of heterogeneous selective ammoxidation and oxidative dehydrogenation (ODH) of light alkanes, particularly of ethane. The conversion of ethane to ethene is in great demand in the domestic and worldwide chemical industry. The review has been voluntarily restricted to metal oxide-type catalysts, as it is devoted to the special issue honouring Edmond Payen and is based on 30 years of experience and discussions with pioneering scientists in the field. The main key factors, designated by Grasselli as the “7 pillars”, have been emphasised: isolation of active sites, M–O bond strength, crystalline structure, redox features, phase cooperation, multifunctionality and the nature of the surface oxygen species. The main features and physical and chemical properties of solid catalysts for selective oxidation compared to total oxidation have also been emphasised. Several case studies have been presented to illustrate the concept and importance of the key factors of catalyst preparation and activation and of the catalytic atmosphere. Based on such analysis and recent discoveries and process developments perspective views are also given. 相似文献
143.
Minghao LiYanlong Gu 《Tetrahedron》2011,67(43):8314-8320
An electrophilic ring-opening reaction of 2-aryl-3,4-dihydropyran with many nucleophiles, such as thiophenols, thiols, benzenesulfinic acid, resorcin, 2-methylfuran, benzamide and allyltrimethylsilane, was developed. In the presence of an appropriate catalyst, a product that contains not only a moiety of the nucleophile but also a fragment of 1,3-dicarbonyl compound was obtained. 相似文献
144.
Loutfy H. Madkour Amera M. Hassanein Mohamed M. Ghoneim Safwat A. Eid 《Monatshefte für Chemie / Chemical Monthly》2001,132(2):245-258
Summary. The inhibition of corrosion of iron in 2 M nitric acid and 2 M sulfuric acid solutions by substituted phenylhydantoin, thiohydantoin, and dithiohydantoin compounds was measured using thermometric,
weight loss, and polarization methods. The three methods gave consistent results. The polarization curves indicated that the
hydantoin compounds act as mixed-type inhibitors. The adsorption of the inhibitors were found to obey the Temkin adsorption isotherm. The higher inhibition efficiency of the additives in nitric with respect to sulfuric acid solution may
be attributed to the reduced formation of soluble quaternary nitrogen salts in nitric acid medium, favouring adsorption of
the parent additive on the metal surface. The obtained results indicate that the corrosion rate of iron in both acids increases
with increasing temperature, both in absence and presence of the tested inhibitors. Kinetic-thermodynamic model functions
and Temkin isotherm data are compared and discussed. The synergistic effect of halide anions on the inhibition efficiency of the hydantoin
compounds was also investigated.
Received June 5, 2000. Accepted (revised) September 13, 2000 相似文献
145.
Matthias Westerhausen Sabine Weinrich Manfred Oßberger Norbert W. Mitzel 《无机化学与普通化学杂志》2003,629(4):575-577
The reaction of calcium‐bis[bis(trimethylsilyl)amide] with two equivalents triethylgallium yields nearly quantitatively the addition product. In the solid state the calcium atoms are coordinated by two nitrogen atoms and two ethyl groups, whereas in solution all ethyl substituents are magnetically equivalent even at low temperatures. The Ca‐C‐Ga two‐electron three‐center bonds show mean Ca‐N and Ca‐C distances of 243 and 268 pm, respectively. 相似文献
146.
147.
钒(Ⅴ)-7-碘-8-羟基喹啉-5-磺酸显色体系测定钢样中的钒 总被引:1,自引:1,他引:0
研究了7-碘-8-羟基喹啉-5-磺酸(H2QSI)在乙醇存在下分光光度法测定钡(Ⅴ)的最佳条件。在乙醇存在下pH4的硫酸介质中,(H2QSI)与V(Ⅴ)形成了红棕色配合物,最大吸收位于506nm处,表观摩尔吸光系数εmax=2.9×103L·mol-1·cm-1,有色配合物组成为V(Ⅴ):(H2QSI)=1:3。钒(Ⅴ)在0-14μg/25mL符合比耳定律、本法用于钢样中的测定,结果满意。H2QSI是光度分析中的一种显色剂,近年来,8-羟基喹啉类试剂用于钒(Ⅴ)的测定已有报道[1]:,H2QSI曾见用于稀土元素的光度测定[2],但用于钒(Ⅴ)的测定尚未见报道。本文研究了V(Ⅴ)与H2QSI的显色反应条件及组成,在pH4的乙醇介质中,V(Ⅴ)与H2QSI生成红棕色配合物ε506nm=2.9×103L·mol-1·cm-1。本方法用于低碳合金钢中钒的测定,结果满意。 相似文献
148.
A new method for introduction w-side chain of prostanoid was described in this note. Starting from acid chloride (3), via Barton radical reaction, a trans α,β-unsaturated ketone sython was introduced. 相似文献
149.
本实验建立了以抗坏血酸为基体改进剂测定蚝油中铅的方法。研究了多种基体改进剂消除蚝油基体对测铅的干扰,方法的相对标准偏差为4.9%,回收率为94%-96%,检出限为1.5ng/mL。本方法可用于蚝油、贻贝油等调味品中铅含量的测定。 相似文献
150.