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1.
Cu–Zr and V–Cu–Zr catalysts were prepared by a precipitation procedure. BET and copper metallic surfaces areas were determined. TOF values indicate that the reaction was structure insensitive and that V imposes a common TOF.
Cu–Zr V–Cu–Zr . . , .相似文献
2.
Takahashi T Tsai FY Li Y Wang H Kondo Y Yamanaka M Nakajima K Kotora M 《Journal of the American Chemical Society》2002,124(18):5059-5067
Selective preparation of pyridine derivatives from two different alkynes and a nitrile was achieved by a novel procedure in which an alkyne and a nitrile couple first to give an azazirconacyclopentadiene followed by reaction with the second alkyne in the presence of 1 equiv of NiCl(2)(PPh(3))(2). This procedure gives only single products of pyridine derivatives from two different symmetrical alkynes and a nitrile. Our novel procedure can be used even with two similar alkyl-substituted alkynes such as 3-hexyne and 4-octyne. Two possible pyridine isomers from 3-hexyne, 4-octyne, and acetonitrile could be completely and independently prepared as single products by this method. The origin of the selectivity comes from the addition order of two different alkynes. This method was applied for the formation of pyridones and iminopyridines using isocyanate and carbodiimide derivatives instead of nitriles, respectively. Reaction of an alkyne with Cp(2)ZrEt(2) and an isocyanate or a carbodiimide gives an azazirconacycle. Treatment of the azazirconacycle with the second alkyne in the presence of 1 equiv of NiCl(2)(PPh(3))(2) gave a pyridone or an iminopyridine derivative. The use of two different unsymmetrical alkynes afforded the pyridine with five different substituents when the first alkyne has a trialkylsilyl group and the second alkyne has a phenyl group as functional groups. On the other hand, azazirconacyclopentadienes reacted with propargyl bromide in the presence of CuCl with excellent regioselectivity to give tetrasubstituted pyridine derivatives as single products. With the assistance of the trialkylsilyl groups, pyridines with all different substituents including H were also prepared. 相似文献
3.
Takahashi T Liu Y Iesato A Chaki S Nakajima K Kanno K 《Journal of the American Chemical Society》2005,127(34):11928-11929
The reaction of diarylalkynes with Cp2ZrBu2 and successive treatment with CrCl3 afforded linear tetramers of diarylalkynes, (1E,3E,5E,7E)-octatetraenes. On the other hand, dialkylalkynes did not give the corresponding octatetraenes but cyclized products, such as pyridines and pyridones, by the reaction with nitriles and isocyanates. 相似文献
4.
Crossing paths with rhodium: A cationic Rh(I)/H(8)-BINAP complex has been found to catalyze the linear cross-trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides to give substituted trienes. The asymmetric linear cross-trimerization, giving substituted chiral dienes, has also been achieved by using monosubstituted alkenes and (R)-BINAP instead of terminal alkynes and H(8)-BINAP (see scheme; H(8)-BINAP = 2,2'-bis(diphenylphosphino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl; BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl]). 相似文献
5.
Although the high sensitivity, high selectivity and fast response make emission (fluorescence) based technique as one of the most promising tool for developing the chemosensors for metal ions, the past few years have witnessed a demand for the absorption based chemosensors for paramagnetic heavy metal ions, especially Cu2+. Being paramagnetic, Cu2+ leads to the low signal outputs (“turn-off”) caused by decreased emission which may sometimes give false positive response, rendering the emission based technique less reliable for analytical purposes. Herein, we report synthesis and characterization of a hetarylazo derivative, characterized by a strong charge-transfer band which gets attenuated convincingly in the presence of Cu2+ leading to distinct naked-eye color change (yellow to purple), and to a lesser extent in the presence of Cd2+, Zn2+, Co2+, Pb2+, Fe2+, Ni2+, Fe3+ and Hg2+ for which the naked eye sensitivity was comparatively (w.r.t. Cu2+) much less. No response was observed for the other metal ions including Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Ag+, Zn2+, Cd2+, Pb2+, and lanthanides Ce3+, La3+, Pr3+, Eu3+, Nd3+, Lu3+, Yb3+, Tb3+, Sm3+, Gd3+. The proposed sensing mechanism has been ascribed to the stabilization of LUMO after complexation with Cu2+ and a 1:1 stoichiometry has been deduced. 相似文献
6.
1,2-Dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides can be selectively realized through using different reaction conditions. α,β-Dihalo alkenes were obtained exclusively using THF as solvent without using any catalyst, while α,α-dihalo ketones were synthesized using a mixed solvent of THF and H2O in the presence of FeCl3·6H2O. Terminal aromatic alkynes are smoothly transformed into α,α-dihalo ketones on water without a catalyst. 相似文献
7.
Reusable Cu2O/PPh3/TBAB system for the cross-couplings of aryl halides and heteroaryl halides with terminal alkynes 总被引:1,自引:0,他引:1
An efficient and reusable Cu2O/PPh3/TBAB (n-Bu4NBr) system for the cross-coupling reactions of aryl and heteroaryl halides with terminal alkynes has been developed. Four types of Cu2O, including bulky Cu2O, cubic Cu2O nanoparticles, octahedral Cu2O nanoparticles, and spherical Cu2O nanoparticles, were examined, and the octahedral Cu2O nanoparticles were found to be the most effective catalyst for the reaction. In the presence of the octahedral Cu2O nanoparticles, PPh3, and TBAB, a variety of aryl and heteroaryl halides were reacted with alkynes including alkynols smoothly in moderate to good yields. Noteworthy is that the Cu2O/PPh3/TBAB system can be recovered and reused several times without loss of any activities. 相似文献
8.
H. Sharghi R. Khalifeh F. Moeini M. H. Beyzavi A. Salimi Beni M. M. Doroodmand 《Journal of the Iranian Chemical Society》2011,8(1):S89-S103
The use of 2 mol% of Cu/C nanoparticles, as an easily accessible and inexpensive heterogeneous catalyst, promoted a one-pot three-component condensation of an amine, aldehyde, and an alkyne in water to produce the corresponding propargylamine in good to high yields. This method was proved to be applicable to a wide range of substrates and is especially practical for the synthesis of new azacrown ether derivatives. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for at least ten times with almost consistent activity. 相似文献
9.
《应用有机金属化学》2017,31(12)
In the presence of a catalytic amount of KI combined with oxidant m CPBA, a convenient catalytic procedure is developed for the preparation of 3‐selanylindoles from indoles and diselenides. In this protocol, KI is first oxidized by m CPBA into hypoiodous acid, which reacts with diselenide to cleave Se‐Se bond. The in situ generated active electrophilic selenium species then reacts with indole, affording 3‐selanylindole via an electrophilic substitution mechanism. This catalytic selenation of indoles has mild reaction conditions and is a simple procedure, which extends the synthetic application of KI in organic synthesis. 相似文献
10.
The new Cu-Co based (Cu/Co/Zn/Zr) catalysts for higher-alcohol synthesis were prepared using coprecipitation method, plasma enhanced method and reverse coprecipitation method under ultrasound irradiation. The catalysts were investigated by the means of BET, SEM, XRD, H2-TPR and XPS. Catalytic properties of the catalysts prepared by various methods were examined using CO hydrogenation reaction. It was found that plasma enhanced method and reverse coprecipitation method under ultrasound irradiation were both effective in enhancing the catalytic properties of Cu/Co/Zn/Zr mixed oxides. The small particle size, high dispersion of active components, the improvement of specific surface area and surface contents of active phases could account for the excellent performance of the experimental Cu/Co/Zn/Zr catalysts. 相似文献
11.
Although the high sensitivity, high selectivity and fast response make emission (fluorescence) based technique as one of the most promising tool for developing the chemosensors for metal ions, the past few years have witnessed a demand for the absorption based chemosensors for paramagnetic heavy metal ions, especially Cu(2+). Being paramagnetic, Cu(2+) leads to the low signal outputs ("turn-off") caused by decreased emission which may sometimes give false positive response, rendering the emission based technique less reliable for analytical purposes. Herein, we report synthesis and characterization of a hetarylazo derivative, characterized by a strong charge-transfer band which gets attenuated convincingly in the presence of Cu(2+) leading to distinct naked-eye color change (yellow to purple), and to a lesser extent in the presence of Cd(2+), Zn(2+), Co(2+), Pb(2+), Fe(2+), Ni(2+), Fe(3+) and Hg(2+) for which the naked eye sensitivity was comparatively (w.r.t. Cu(2+)) much less. No response was observed for the other metal ions including Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ba(2+), Mn(2+), Ag(+), Zn(2+), Cd(2+), Pb(2+), and lanthanides Ce(3+), La(3+), Pr(3+), Eu(3+), Nd(3+), Lu(3+), Yb(3+), Tb(3+), Sm(3+), Gd(3+). The proposed sensing mechanism has been ascribed to the stabilization of LUMO after complexation with Cu(2+) and a 1:1 stoichiometry has been deduced. 相似文献
12.
Kawaguchi S Nagata S Nomoto A Sonoda M Ogawa A 《The Journal of organic chemistry》2008,73(20):7928-7933
A novel transition-metal-catalyzed hydrophosphination of terminal alkynes using a diphosphine-hydrosilane binary system takes place regioselectively to provide vinylic phosphines, which undergo air oxidation during workup, affording the corresponding vinylphosphine oxides in good yields. In this hydrophosphination, hydrosilanes act as a useful hydrogen source, and furthermore, small amounts of oxygen is required to accomplish the reaction efficiently. 相似文献
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14.
Yasuo Wakatsuki 《Journal of organometallic chemistry》2004,689(24):4092-4109
This review focuses on the tautomerization mechanism between alkynes and vinylidene units taking place in the coordination sphere of transition metal fragments. Reactions of vinylidene complexes as well as catalytic reactions involving a metal-vinylidene intermediate are also reviewed from the mechanistic point of view. 相似文献
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16.
Sibo Chen Kai Mei Yaru Luo Liang-Xin Ding Haihui Wang 《Journal of Energy Chemistry》2023,(10):439-446
The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of th... 相似文献
17.
Mariappan Periasamy Mallesh Beesu D. Shyam Raj 《Journal of organometallic chemistry》2008,693(17):2843-2846
Iron carbonyl complexes prepared in situ using the Fe(CO)5/NaH/MeI reagent combination and alkynes at 25 °C give the corresponding cyclobutenediones in 50-65% yields after CuCl2 · 2H2O oxidation. 相似文献
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19.
Masaaki Yoshifuji Kerrie I. Gell Jeffrey Schwartz 《Journal of organometallic chemistry》1978,153(2):C15-C18
Alkynes induce reductive elimination of alkane from Cp2Zr(H)(R); zirconacyclopentadienes are formed as well. 相似文献
20.