共查询到20条相似文献,搜索用时 781 毫秒
1.
Ping Yan Patrice Batamack G. K. Surya Prakash George A. Olah 《Catalysis Letters》2005,101(3-4):141-143
Gallium triflate catalyzed dehydration of aldoximes to nitriles is described in good to excellent yields. Good catalytic and dehydrating capabilities of gallium triflate are demonstrated through this dehydration reaction. 相似文献
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Catalytic Friedel–Crafts acylation of heteroaromatics has been achieved using metal triflates as catalysts. While conventional Friedel–Crafts acylation often requires the use of more than stoichiometric amounts of aluminum chloride, metal triflates such as tin(II) triflate, scandium triflate, and gallium triflate, etc. have enabled efficient acylation reactions by catalytic use. 相似文献
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通过对陇东南地区5号煤层煤样的显微煤岩组分分析、工业分析以及微量元素分析统计,得出该研究区内镓元素含量与灰分产率、煤灰中Al2O,和SiO2呈正相关,由于受陆源碎屑影响,主要以无机态赋赋存于粘土矿物之中;砷含量随煤中全硫增长而增大,以有机结合态存在;磷元素以无机态为主,与煤中全硫、砷元素含量正相关。 相似文献
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An efficient solid Lewis acid, has been synthesized by loading cerium triflate (7 wt%) on the acid activated fly ash with high silica content (81%). The physico-chemical properties of synthesized fly ash-supported cerium triflate catalyst (CFT) were monitored by XRD, FT-IR spectroscopy, FT-IR spectroscopy of the ammonia adsorbed catalyst, SEM-EDAX, TEM, Flame Atomic Absorption Spectrophotometer and TG-DTA study. The increased concentration of silica surface hydroxyl groups on activated fly ash have a major influence on the loading of cerium triflate. The catalytic activity of the catalyst CFT was tested in the acylation of veratrole using acetic anhydride as the acylating agent. The proposed model structure of CFT shows that the triflate species withdraws the electron density from the surface cerium making it electron deficit and generate Lewis acidity on the surface of fly ash as confirmed by NH3 adsorbed FT-IR spectrum. The activity data indicate that this heterogeneous catalyst is very active, corresponding to high conversion (88%) of veratrole to 3,4-dimethoxyacetophenone. The catalyst could be easily recovered and reused giving similar conversion up to three reaction cycles indicating its stability under experimental conditions. Thus fly ash-supported cerium triflate is a novel and efficient catalyst and is a promising way of bulk utilization of waste fly ash by developing cost effective catalyst system for industrially important Friedel–Crafts acylation reactions. 相似文献
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Thierry Ollevier Etienne Nadeau Jean‐Christophe Eguillon 《Advanced Synthesis \u0026amp; Catalysis》2006,348(15):2080-2084
Bismuth triflate was found to be an efficient catalyst in the Mannich‐type reaction of silyl enolates with N‐alkoxycarbonylamino sulfones. The reaction proceeded smoothly with a low catalyst loading of bismuth triflate (0.5–1.0 mol %) to afford the corresponding protected β‐aminocarbonyl compound in very good yields (up to 96 %). 相似文献
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Summary The ring-opening polymerization of 2-phenyl aziridine was studied with several catalyst systems: boron trifluoride etherate, chlorhydric acid, perchloric acid, dimethyl sulfate and methyl triflate. The corresponding polyamine was obtained as a pale yellow solid with a number average molecular weight around 2,000–3,000.A kinetic study is discussed in the case of perchloric acid and methyl triflate. 相似文献
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Zhiyuan Chen Xingxin Yu Mingchao Su Xiaodi Yang Jie Wu 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2702-2708
An efficient tandem reaction of 2‐alkynylbenzaldoximes with isocyanides co‐catalyzed by silver triflate and bismuth triflate has been developed, which gives rise to the unexpected N‐(isoquinolin‐1‐yl)formamides in good to excellent yields. The iodo‐ and bromo‐containing products could be obtained as well by variation of the reaction conditions. 相似文献
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介绍了一步关环合成2-丁基-6-硝基吲哚的新方法。室温氮气保护下,2-氨基-4硝基苯酚与三氟乙酰酐反应进行氨基保护,得到的2-(N-三氟甲基乙酰基)氨基-4-硝基苯酚与N-苯基双(三氟甲烷磺酰)亚胺(PhNTf2)在强碱 NaH作用下,生成三氟甲基磺酸酯,收率82.6%。之后,70~80 ℃氮气保护下,Pd(PPh3)4催化剂作用,与正己炔一步关环合成2-丁基-6-硝基吲哚,收率33.3%。产物结构经红外光谱、核磁共振和质谱检测并证实。将目标产物进行单晶培养,经单晶X衍射检测表征,阐明了结构。 相似文献
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Michael J Erickson 《Polymer》2004,45(10):3389-3397
Gel electrolytes were prepared by crosslinking low molecular weight poly(ethylenimine) (PEI) with tetraethylene glycol diacrylate (TEG) in the presence of 2-methoxyethyl ether (diglyme) and lithium triflate (LiTf). Impedance and infrared (IR) spectroscopies were used as complimentary tools for studying the mode of ion conduction in these gel electrolytes. Ionic conductivity measurements for all samples tested exhibited significant LiTf and diglyme composition dependency. The maximum ionic conductivity at 20 °C was 2×10−4 S/cm with moderate LiTf and high diglyme compositions. The calculated molal concentration of non-ionically bound ‘free’ triflate ion was found to vary directly with ionic conductivity with the highest molality ‘free’ triflate samples yielding the highest ionic conductivity. Lithium ion interactions with the triflate ion, diglyme and the crosslinked polymer matrix were observed with IR spectroscopy. A lower frequency shoulder on the vs(CO) vibrational mode increases in intensity as LiTf composition is increased. Curve fitting and molar calculations suggest that over 85% of the total lithium ions available are coordinated to the TEG carbonyl at dilute LiTf compositions. 相似文献
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The preparation of polycrystalline gallium beta-alumina samples using molten gallium and gallium dichloride is described. Gallium was selectively electrochemically transferred through a gallium beta alumina membrane from a gallium tin alloy. 相似文献
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Zhiyuan Chen Qiuping Ding Xingxin Yu Jie Wu 《Advanced Synthesis \u0026amp; Catalysis》2009,351(10):1692-1698
Different outcomes were generated under different conditions for the tandem reactions of N′‐(2‐alkynylbenzylidene)hydrazides with dimethyl acetylenedicarboxylate (DMAD) catalyzed by silver triflate or in the presence of electrophiles. The unexpected isoquinoline‐based azomethine ylides were obtained when the reaction was catalyzed by silver triflate or in the presence of bromine, while the fused 1,2‐dihydroisoquinolines were afforded when iodine was employed in the above tandem reactions. 相似文献
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Silicon - In this paper, Gallium Nitride (GaN) based Dielectric Engineered High-K GaN Schottky Nanowire Field Effect Transistor (DE-HK-GaN-SNWFET) is examined for enhancing analog performance for... 相似文献
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Shahzada Ahmad M. Deepa Vikram Sen Samrana Kazim S. K. Agarwal 《Polymer Engineering and Science》2011,51(8):1513-1518
The electropolymerization of pyrrole in ionic liquid media was carried out to produce an adherent, uniform, and durable polypyrrole (PPy) films with enhanced electrical properties. A threefold increase in the conductivity value can be attained with the selective choice of polymerizing media and ambient temperature dc conductivity value of 43, 15, and 13 S cm?1 for films grown in 1‐ethyl‐3‐methylimidazolium bis(perfluoroethanesulfonyl)imide, 1‐ethyl‐3‐methylimidazolium triflate and in lithium triflate in acetonitrile respectively. The corresponding localization lengths were found to be 17, 33, and 48 nm indicate that carriers are strongly localized. At low temperature, all three types of PPy films show metallic type behavior. Though transition is observed above 200 K for all the three films, the charge transport mechanism remains unaltered at higher temperatures for the films grown in ionic liquids, while the film grown in lithium triflate in acetonitrile assumes a three‐dimensional variable range hopping conduction behavior. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers 相似文献
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《Catalysis communications》2008,9(3):465-469
The direct alkylation of caffeine (1), by ethyl triflate gave 1,3,7-trimethyl-9-ethylxanthinium triflate (2) which led to 1,3,7-trimethyl-9-ethylxanthinium bis(trifluoromethanesulfonyl)amide (3) after methathesis with LiNTf2; 3 proved to be an ionic solid which can be used for the recovery of metal triflates (M(OTf)n with M = Sc, La, Yb, Cu, Hf, Bi). These reusable catalysts proved to be efficient Lewis acids for Diels–Alder reactions leading to very little or no polymerisation of the diene. In the case of bismuth (III) triflate, the catalyst can be recovered and reused at least 10 times without loss of activity. 相似文献
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Sridhar Madabhushi Venkata Sairam Vangipuram Kishore Kumar Reddy Mallu Narsaiah Chinthala China Ramanaiah Beeram 《Advanced Synthesis \u0026amp; Catalysis》2012,354(8):1413-1416
The synthesis of polyfunctionalized pyrroles by reaction of a ketoxime with dimethyl acetylenedicarboxylate using europium(III) triflate as the catalyst is described. 相似文献
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K Srinivasa Rao D Sarangi PK Dash G Roy Chaudhury 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(5):555-561
Gallium extraction studies were carried out using resin containing an hydroxamic acid functional group. Extraction was dependant on reaction time and alkali concentration. The resin did not extract aluminium. Vanadium extraction kinetics were slower than those of gallium. The gallium and vanadium separation efficiency increased with decreasing contact time with extractions of 64% and 32% respectively after 1 min. Gallium extraction was independent of alkali concentration up to 250 g dm?3 and thereafter decreased with increasing alkali concentration. Vanadium extraction decreased with increasing alkali concentration. Cyclic batch and column studies were carried out with synthetic as well as actual Bayer liquor to test the stability and preferential extraction of gallium using the resin. It was observed that using resin partially loaded with gallium, the co‐extraction of vanadium could be minimised. Copyright © 2003 Society of Chemical Industry 相似文献
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Yan‐Chao Wu Hui‐Jing Li Li Liu Nicolas Demoulin Zhe Liu Dong Wang Yong‐Jun Chen 《Advanced Synthesis \u0026amp; Catalysis》2011,353(6):907-912
The direct Friedel–Crafts reaction of chromene hemiacetals with indoles, furans and sterically hindered anilines has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of hafnium triflate [Hf(OTf)4, 0.1 mol%, 0–40 °C]. The mild conditions tolerate various sensitive functional and protecting groups, and the products were confirmed unambiguously from their spectra and by single‐crystal X‐ray analysis. This direct Friedel–Crafts reaction of chromene hemiacetals should inspire and encourage the consideration of hafnium triflate in the development of mild reaction conditions for the efficient derivatization of hemiacetal‐containing compounds. 相似文献