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1.
The effect of the state of hydrated surface of the bulk oxide photocatalysts, TiO2, CeO2, and ZnO on the rate of UV-induced oxidation of CO with atmospheric oxygen was studied. The activity of dehydroxylated catalyst samples evacuated at temperatures of >350 °C toward CO photooxidation decreases in the series CeO2 > ZnO ≈ TiO2, while that of partially hydrated samples after pretreatment at 20 °C changes in the order TiO2 > ZnO ≥ CeO2 ≈ 0. According to the results, the difference in the photocatalytic activity toward CO oxidation on the dehydrated ZnO, TiO2, and CeO2 catalysts is attributable to different concentrations of oxygen vacancies, which are formed more readily after high-temperature treatment on ZnO and CeO2 and thus promote higher rate of CO photooxidation. Using a new technique for recording transmittance IR spectra, it was found that photoirradiation in the presence of adsorbed water and O2 gives peroxides and hydroperoxides, with their concentrations decreasing in the series TiO2 >> ZnO >> CeO2. Most likely, these species are active intermediates of CO photooxidation with oxygen in the presence of adsorbed water. The hydrophobization effect was detected upon TiO2 modification with zinc, resulting in removal of surface acid sites capable of adsorbing water. The TiO2 modification with zinc increases the activity of CO photooxidation with respect to the oxidation catalyzed by samples pretreated at low temperatures (20—60 °C). 相似文献
2.
(2S,4S)-2-(tert-Butyl)-5-oxo-1,3-dioxolan-4-acetic acid ( 1 ) was dilithiated to the enolate 2 in toluene and THF with lithium diisopropylamide (LiN(i-Pr)2) under various conditions. Deuteration experiments with 2 showed that two different stable forms of the enolate could be produced, depending on whether the deprotonation of 1 had been carried out in toluene or THF. The generated (i-Pr)2NH was coordinated to the enolate and, hence, served as a strong lipophilic solvating agent. LiN(i-Pr)2 could substitute the amine ligands of the two species to a different extent. THF was partially able to displace (i-Pr)2NH that solvated the species produced in toluene, but the coordination of the amine to the one produced in THF was quantitive. Correlations with given explanations are made. 相似文献
3.
《应用有机金属化学》2017,31(12)
A series of zinc silylamido complexes bearing non‐symmetric β ‐diketiminate ligands were synthesized and structurally characterized. Ring‐opening polymerization (ROP) of rac ‐lactide catalyzed by these zinc complexes afforded heterotactic polylactides at room temperature (P r = 0.79 ~ 0.83 in THF). The steric and electronic characteristics of the ancillary ligands showed significant influence on the polymerization performance of the corresponding zinc complexes. All these zinc complexes also showed moderate activities toward the polymerization of ε ‐caprolactone at ambient temperature in toluene, producing polycaprolactones (PCLs) with high molecular weights and moderate polydispersities. PCL‐b ‐PLLA copolymers could be obtained via three different copolymerization strategies (one‐pot polymerization, and sequential addition of the two monomers in either order) by adopting complex 6 as the initiator through the adjustment of reaction temperatures. The diblock nature of the copolymers was confirmed by 13C NMR spectroscopy and DSC analysis. 相似文献
4.
Reactivity of mixed organozinc and mixed organocopper reagents: 11. Nickel‐catalyzed atom‐economic aryl–allyl coupling of mixed (n‐alkyl)(aryl)zincs
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Melike Kalkan 《应用有机金属化学》2014,28(9):725-732
Group selectivity in the allylation of mixed (n‐butyl)(phenyl)zinc reagent can be controlled by changing reaction parameters. CuCN‐catalyzed allylation in tetrahydrofuran (THF)–hexamethylphosphoric triamide is n‐butyl selective and also γ‐selective in the presence of MgCl2, whereas CuI‐catalyzed allylation in THF in the presence of n‐Bu3P takes place with a n‐butyl transfer:phenyl transfer ratio of 23:77 and an α:γ transfer ratio of phenyl of 76:24. NiCl2(Ph3P)2‐catalyzed allylation in the presence of LiCl is phenyl selective with an α:γ ratio of 65:35. The reaction of methyl‐ or n‐butyl(aryl)zinc reagents with an allylic electrophile in THF at room temperature in the presence of NiCl2(Ph3P)2 catalyst and LiCl as an additive provides an atom‐economic alternative to aryl–allyl coupling using diarylzincs. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
5.
A Cationic Zinc Hydride Cluster Stabilized by an N‐Heterocyclic Carbene: Synthesis,Reactivity, and Hydrosilylation Catalysis
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Dr. Arnab Rit Dr. Alessandro Zanardi Dr. Thomas P. Spaniol Prof. Dr. Laurent Maron Prof. Dr. Jun Okuda 《Angewandte Chemie (International ed. in English)》2014,53(48):13273-13277
The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4(THF)](BPh4)2 ( 1 ) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Brønsted acid or by addition of the putative zinc dication [(IMes)Zn(THF)]2+. A triply bridged thiophenolato complex 2 was formed upon oxidation of 1 with PhS? SPh. Protonolysis of 1 by methanol or water gave the corresponding trinuclear dicationic derivatives. At ambient temperature, 1 catalyzed the hydrosilylation of aldehydes, ketones, and nitriles. Carbon dioxide was also hydrosilylated under forcing conditions when using (EtO)3SiH, giving silylformate as the main product. 相似文献
6.
Chiral Gallium and Indium Alkoxometalates Li2(S)‐BINOLate ((S)‐BINOL = (S)‐(–)‐2,2′‐Dihydroxy‐1,1′‐binaphthyl) generated by dilithiation of (S)BINOL with two equivalents nBuLi was reacted with GaCl3 und InCl3 in THF to the alkoxometalates [{Li(THF)2}{Li(THF)}2{Ga((S)‐BINOLate)3}] ( 1 ) and [{Li(THF)2}2{Li(THF)}{In((S)‐BINOLate)3}] · [{Li(THF)2}{Li(THF)}2{In((S)‐ BINOLate)3}]2 ( 3 ), respectively. 1 and 3 crystallize from THF/toluene mixtures as 1 · 2 toluene and 3 · 8 toluene. The treatment of PhCH2GaCl2 with Li2(S)‐BINOLate in THF under reflux, followed by recrystallization of the product from DME gives the gallate [{Li(DME)}3{Ga((S)BINOLate)3}] · 1.5 THF ( 2 · 1.5 THF). 1 – 3 were characterized by NMR, IR and MS techniques. In addition, 1 · 2 toluene, 2 · 1.5 THF and 3 · 8 toluene were investigated by X‐ray structure analyses. According to them, a distorted octahedral coordination sphere around the group 13 metal was formed, built‐up by three BINOLate ligands. The three Li+ counter ions act as bridging units by metal‐oxygen coordination. The coordination sphere of the Li+ ions was completed, depending on the available space, by one or two THF ligands ( 1 · 2 toluene, 3 · 8 toluene) and one DME ligand ( 2 · 1.5 THF), respectively. The sterical dominance of the BINOLate ligands can be shown by the almost square‐planar coordination of the Li+ ions in 2 · 1.5 THF giving a small twisting angle of only 17°. 相似文献
7.
Cédric Balan Roxana Pop Virginie Comte Didier Poinsot Virginie Ratovelomanana‐Vidal Pierre Le Gendre 《应用有机金属化学》2014,28(7):517-522
The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)‐SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation under argon atmosphere or under hydrogen pressure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Lanthanide‐catalyzed addition of diethyl phosphite with chalcones was achieved under mild conditions. The reaction exhibited good product selectivity using different catalysts. γ‐Oxophosphonates were obtained in high yields in the reactions catalyzed by Yb(OAr)3(THF)2, while those catalyzed by [(Me3Si)2N]3La(μ‐Cl)Li(THF)3 afforded 1,2‐oxaphospholane‐5‐phosphonates as the main products in moderate to good yields. This methodology provides facile and practical approaches to the corresponding organophosphorus compounds with biological interest. 相似文献
9.
A Highly Red‐Emissive Lead‐Free Indium‐Based Perovskite Single Crystal for Sensitive Water Detection
Lei Zhou Jin‐Feng Liao Zeng‐Guang Huang Jun‐Hua Wei Xu‐Dong Wang Wen‐Guang Li Hong‐Yan Chen Dai‐Bin Kuang Cheng‐Yong Su 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5331-5335
Low‐dimensional luminescent lead halide perovskites have attracted tremendous attention for their fascinating optoelectronic properties, while the toxicity of lead is still considered a drawback. Herein, we report a novel lead‐free zero‐dimensional (0D) indium‐based perovskite (Cs2InBr5?H2O) single crystal that is red‐luminescent with a high photoluminescence quantum yield (PLQY) of 33 %. Experimental and computational studies reveal that the strong PL emission might originate from self‐trapping excitons (STEs) that result from an excited‐state structural deformation. More importantly, the in situ transformation between hydrated Cs2InBr5?H2O and the dehydrated form is accompanied with a switchable dual emission, which enables it to act as a PL water‐sensor in humidity detection or the detection of traces of water in organic solvents. 相似文献
10.
Fulu Zhao 《Tetrahedron》2004,60(44):9945-9951
The reaction of 2-fluoroalkyl-1-iodoethylenes with arylamines (1) and the subsequent acid promoted transformation of the products were described. In the presence of ZnCl2 and triethylamine, 1 reacted readily with various p-substituted anilines in HMPA under a vacuum of 60-70 mmHg to give the corresponding enaminoaldehydes (2) as a mixture of E- and Z-isomers. Cyclization of 2, without further purification in refluxing toluene, catalyzed by strong acids such as p-toluene sulfonic acid and trifluoromethanesulfonic acid gave 2-fluoroalkylquinolines (3) in good yields, while fluoroalkylated enaminoketones (4) were obtained predominantly when 2 was treated with acids in aqueous THF solution. A possible mechanism was proposed for the formation of 3 and 4. 相似文献
11.
Kentaro Okuma Jun-ichi Seto Ken-ichi Sakaguchi Saori Ozaki Noriyoshi Nagahora Kosei Shioji 《Tetrahedron letters》2009,50(24):2943-1400
Reaction of 2-phenylethynyl N-tosylanilide prepared by Pd-free procedure with ZnBr2 (3 equiv) in refluxing toluene gave N-tosyl-2-phenylindole in 93% yield. Treatment of 2-phenylethynylaniline with ZnBr2 (1 equiv) in refluxing toluene resulted in the formation of 2-phenylindole in 91% yield. Catalytic ZnBr2 (0.05 equiv) effectively reacted with 2-alkynylanilines to afford 2-substituted indoles in high yields. Thus, complete Pd-free zinc catalyzed hydroamination of 2-alkynylanilines was achieved. 相似文献
12.
Heimei Yuki Yoshio Okamoto Yoshiteru Kuwae Koichi Hatada 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1933-1946
o-Methoxystyrene was polymerized with n-butyllithium (n-BuLi), Na naphthalene, and K dispersion as initiators in tetrahydrofuran (THF) and toluene. The stereoregularity of the polymer was investigated by means of the NMR spectroscopy. The methoxy resonance of the spectrum split into ten components due to the tactic pentads. It was found by x-ray examination that the polymer obtained by n-BuLi in toluene at ?45°C was crystalline and highly isotactic. In THF, the stereospecificity of the polymerization was independent of the initiator, and the isotacticity of the polymer increased with increasing reaction temperature. In toluene, the stereospecificity depended on the initiator; i.e., n-BuLi gave a polymer with higher isotacticity than that given by phenylsodium. The fraction of isotactic triad of the polymer obtained by n-BuLi in toluene at ?78°C was more than 90%, but 50% at 50°C. The presence of ca. 1% THF in toluene led to a steep decrease in the isotacticity even at ?78°C. The tacticity of the polymer given by Na naphthalene was not affected by the existence of NaB(C6H5)4 in THF. The polymerization in THF could be explained by Bovey's “single σ” process, while a penultimate effect was observed in the polymerization by n-BuLi in toluene. 相似文献
13.
Markus A. Putzer Astrid Pilz Ulrich Müller Bernhard Neumüller Kurt Dehnicke 《无机化学与普通化学杂志》1998,624(8):1336-1340
Amido Complexes of Manganese(II). Syntheses and Crystal Structures of [Mn(NPh2)2(THF)]2 and Na2[Mn(NPh2)4] · 2 C7H8 The silylated amido complex [Mn{N(SiMe3)2}2 · (THF)] reacts in toluene solution with diphenylamine under ligand exchange to form the diphenylamido complex [Mn(NPh2)2(THF)]2 ( 1 ), which forms orange-red columnar crystals. 1 reacts in THF solution with NaN(SiMe3)2 and after crystallization from toluene yellow-orange Na2[Mn(NPh2)4] · 2 C7H8 ( 2 ) is obtained. According to the crystal structure analyses the manganese atoms in 1 (space group P21/c, Z = 2) are linked via the N atoms of two of the NPh2– groups to form centrosymmetric Mn2N2 four-membered rings with Mn–N bonds of almost the same length. 2 (space group I41/a, Z = 4) forms a three-dimensional space-lattice structure, which arises from ”︁inner solvation”︁”︁ of the sodium atoms with the phenyl rings of the NPh2– group. 相似文献
14.
Yuko Suzuki Prof. Dr. Takahiro Sasamori Dr. Jing‐Dong Guo Prof. Dr. Shigeru Nagase Prof. Dr. Norihiro Tokitoh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13784-13788
Treatment of 2,5‐di(3,5‐tert‐butylphenyl)‐1‐lithioferrocene with GeCl2?dioxane afforded the corresponding chlorogermylenoid that exhibited an ambident reactivity in different solvents; it displayed a behavior characteristic for a dichlorogermylene anion in THF, while it exhibited the typical reactivity of a chlorogermylene in toluene. X‐Ray diffraction analysis of a single crystal of this chlorogermylenoid, obtained from recrystallization in THF, revealed a separated‐ion‐pair structure in the solid state. 相似文献
15.
Annika Katharina Reitz Qian Sun René Wilhelm Dirk Kuckling 《Journal of polymer science. Part A, Polymer chemistry》2017,55(5):820-829
The synthesis of poly(trimethylene carbonate) via carbene catalyzed ring‐opening polymerization (ROP) was investigated. The N‐heterocyclic carbenes were protected as CO2‐adducts to improve their handling (e.g., carbene generation without base). The influence of catalyst structure, different solvents and microwave radiation on conversion, molecular weight and end groups was investigated to gain an insight into the reaction mechanism. Different NHC structures were investigated for their catalytic activity toward the ROP of trimethylene carbonate. The analytic studies were performed by using NMR spectroscopy, SEC and ESI‐IMS mass spectrometry. It was found that the reaction can be performed in acetonitrile, toluene, THF and CH2Cl2. Synthesis in CH2Cl2 allows the best control over the resulting polymer with regards to polydispersity and molecular weight. Microwave radiation accelerates the reaction at 80 °C. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 820–829 相似文献
16.
E. Klähne C. Giannotti H. Marquet-Ellis G. Folcher R.D. Fischer 《Journal of organometallic chemistry》1980,201(2):399-410
Photo-induced reduction of two organouranium complexes of the type Cp3UR (R = CH3 and n-C4H9) was studied in toluene and THF solution at various temperatures. Optimal conditions for the production of Cp3U . THF as the final product involve UV/VIS irradiation in THF at ca. 60°C. Spin trap experiments indicate that, at least in THF, intermediate free radicals participate. The results, including gas chromatographic, mass spectroscopic and 1H NMR spectroscopic measurements, are discussed in terms of a virtually first order multi-step process involving discrete radical pairs kept together efficiently by solvent cages so that H-atom abstraction from a Cp ligand followed by decomposition of the organometallic product is largely avoided. 相似文献
17.
J. Michalik J. Sadlo T. Kodaira S. Shimomura H. Yamada 《Journal of Radioanalytical and Nuclear Chemistry》1998,232(1-2):135-138
Silver cationic clusters formed in γ-irradiated AgCs-rho zeolites in hydrated and dehydrated forms have been studied by electron
spin resonance (ESR) spectroscopy and diffuse reflectance spectrophotometry. It was found that tetrameric silver clusters,
Ag
4
3+
in dehydrated zeolites and Ag
4
2+
in hydrated samples, are stabilized at room temperature. Tetrameric silver is trapped inside octagonal prism of zeolite framework
and does not show any noticeable decay as far as samples are evacuated. 相似文献
18.
Syntheses and Structure Elucidations of Novel (Ironcarbonyl)zinc and ‐cadmium Chloride Derivatives Reactions of zinc/cadmium chloride with Na2[Fe(CO)4] lead to a number of new (iron carbonyl)zinc/cadmium chlorides, wherein the reaction course depends on the used solvent used. In the reaction of ZnCl2 with Na2[Fe(CO)4], three new substances can be prepared. The compound [Zn2Cl2Fe(CO)4(THF)2] ( 1 ), which consists of neutral polymeres, is formed in THF, the ionic compound [Na(DME)3][Zn2Cl3Fe(CO)4] ( 2 ) forms in DME, and from a mixture of THF and TMEDA the compound [Zn2Cl2Fe(CO)4(TMEDA)2] ( 3 ) is obtained as a monomere. Also by using CdCl2, the reaction with Na2[Fe(CO)4] in THF leads to the polymeric compound ([(Cd4Cl6)Fe(CO)4(THF)5] ( 4 )). Carrying out the reaction in a mixture of toluene and DME leads to the formation of the ionic compound [Na(DME)3]2[Cd6{Fe(CO)4}6Cl2(DME)2] ( 5 ) in which an annular dianion consisting of twelve metal atoms is found. From an aqueous solution and subsequent work‐up in THF, the compound [Fe(THF)4(H2O)2][Cd8{Fe(CO)4}4Cl9(THF)6]2 ( 6 ) can be prepared which contains an cluster anion that is built of anellated six membered rings. 相似文献
19.
In combination with non-corrosive and low-toxic boric acid, AlCl3 · 6H2O was found to be effective for the synthesis of 5-hydroxymethylfurfural (5-HMF) from glucose. In this work, a 5-HMF yield of ≈ 60 % was obtained at 170°C for 40 min in a H2O/THF biphasic solvent mixture. An addition of NaCl not only improved the partition coefficients but also inhibited by-product formation. THF was identified as an ideal extraction solvent in biphasic systems containing C4 solvents. However, low concentration of ZnCl2, CoCl2 · 6H2O, MnCl2 · 4H2O, NiCl2 · 6H2O, FeCl3 · 6H2O were not suitable for the catalyst system, while ZrOCl2 · 8H2O, InCl3 · 4H2O showed high activity for the reaction. Boric acid increased the amount of Lewis acid sites in the reactive phase and enhanced the isomerization of glucose to fructose. A mechanism of the AlCl3 · 6H2O and boric acid catalyzed glucose dehydration reaction was proposed to proceed through the isomerization of glucose to fructose followed by the transformation of fructose to 5-HMF. 相似文献
20.
On The Remarkably Different Role of Salt in the Cross‐Coupling of Arylzincs From That Seen With Alkylzincs
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Lucas C. McCann Prof. Michael G. Organ 《Angewandte Chemie (International ed. in English)》2014,53(17):4386-4389
The role of halide salt additives has been investigated in the Negishi reaction involving aryl zinc reagents. Diarylzincs readily transmetallate to Pd in relatively non‐polar media (e.g., THF) with zero salt present and coupling proceeds. Arylzinc halides (ArZnX) fail to couple in THF without salt, but do couple with it. However, unlike alkylzincs that form higher‐order zincates in order to facilitate transmetallation, all that is required with arylzincs in an increase in solvent dielectric as even ZnX2 works as an additive, which completely terminates alkylzinc coupling. 相似文献