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排序方式: 共有833条查询结果,搜索用时 0 毫秒
91.
92.
JimmyA. van Rijn Martin Lutz LarsS. vonChrzanowski AnthonyL. Spek Elisabeth Bouwman Eite Drent 《Advanced Synthesis \u0026amp; Catalysis》2009,351(10):1637-1647
A new catalytic method has been investigated to obtain either O‐ or C‐allylated phenolic products using allyl alcohol or diallyl ether as the allyl donor. With the use of new cationic ruthenium(II) complexes as catalyst, both reactions can be performed with good selectivity. Active cationic Ru(II) complexes, having cyclopentadienyl and bidentate phosphine ligands are generated from the corresponding Ru(II) chloride complexes with a silver salt. The structures of three novel (diphosphine)Ru(II)CpCl catalyst precursor complexes are reported. It appears that the structure of the bidentate ligand has a major influence on catalytic activity as well as chemoselectivity. In addition, a strong cocatalytic effect of small amounts of acid is revealed. Model experiments are described that have been used to build a reaction network that explains the origin and evolution in time of both O‐allylated and C‐allylated phenolic products. Some mechanistic implications of the observed structure vs. performance relation of the [(diphosphine)RuCp]+ complexes and the cocatalytic role of added protons are discussed. 相似文献
93.
94.
氧化亚锡催化合成环烷酸酯的研究 总被引:8,自引:1,他引:8
介绍了用氧化亚锡非酸性催化剂催化合成环烷酸系列酯的方法。讨论了醇酸摩尔比、催化剂用量和反应时间等因素对酯化反应的影响 ,最佳反应条件为催化剂用量为反应液的 2 % ( w) ,醇酸摩尔比为 2∶ 1 ,酯化反应时间为 4 h。试验表明氧化亚锡非酸性催化剂是环烷酸和高沸点伯醇、异辛醇、正癸醇、正十二醇等直接酯化的特效催化剂 相似文献
95.
96.
M. Lakshmi Kantam Ujjwal Pal B. Sreedhar Suresh Bhargava Yasuhiro Iwasawa Mizuki Tada B.M. Choudary 《Advanced Synthesis \u0026amp; Catalysis》2008,350(9):1225-1229
The selective oxidation of various alcohols into their corresponding aldehydes and ketones was achieved by ruthenium species stabilized on the nanocrystalline magnesium oxide (NAP‐MgO) by the incorporation of choline hydroxide, a basic ionic liquid, in excellent yields. The procedure is simple, efficient and environmentally benign. The catalyst can be used for four cycles with almost consistent activity. 相似文献
97.
The hydrogenation of dimethyl oxalate(DMO) for the producing of C2-C4 alcohols with methanol as solvent was researched at the temperature of 270 °C to 310 °C. Ethylene glycol(EG) was the main product at low temperature and the selectivity of which was 61.9% at 230 °C. However, EG selectivity decreased sharply with the increase of temperature while ethanol became the main liquid products with the selectivity of 43.5% at 270 °C. It can be ascribed to a thorough hydrogenation of DMO at a high temperature. In addition, the promotion of Guerbet reaction led to the production of propanol and butanol. Simultaneously, the amount of gas products including CO, CO_2 and dimethyl ether(DME) also increased, which became a competition factor in the conversion of DMO to liquid products including C2-C4 alcohols. The blank test was carried out with pure methanol as feedstock with and without Cu/SiO_2 catalyst, which revealed that methanol was involved in the formation of gas products and higher alcohols on Cu-based catalyst, and the main gas product was CO. 相似文献
98.
Maximilian Dyga Andreas Keller Hans Hasse 《American Institute of Chemical Engineers》2022,68(4):e17573
Formaldehyde is an important chemical that is mostly handled in aqueous solutions, which generally also contain methanol; furthermore, also solutions of formaldehyde in other alcohols are used. The density of these solutions is an important thermophysical property. The available models of the density of formaldehyde-containing solutions, however, all have shortcomings, such as a poor accuracy or a limited range of applicability. Therefore, in the present work, a new model of the density in systems of the type (formaldehyde + water + alcohol) was developed. The alcohols that are presently included in the new model are methanol, 1-propanol, and isoprenol; an extension to other alcohols is straightforward. The model was developed using literature data and extensive new density data measured in this work covering binary, ternary, and quarternary solutions of formaldehyde in water, methanol, 1-propanol, and isoprenol at temperatures of K and formaldehyde concentrations of 0.06 − 0.30 g g−1. 相似文献
99.
100.