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1.
Ken‐ichi Itoh Takamitsu Utsukihara Kenji Funayama Hiroshi Sakamaki Miyuki Kanamori T. Tomoyoshi Takahashi Yoshikazu Saitoh Masatoshi Matsushita Liangyou He Chikao Hashimoto Takashi Sugiyama C. Akira Horiuchi 《应用有机金属化学》2007,21(12):1029-1032
The reaction of α,β‐unsaturated ketones with cerium (IV) sulfate tetrahydrate [Ce(SO4)2·4H2O, CS] in acetic acid gave the corresponding β‐acetoxy ketones. In the case of 2‐cyclohexen‐1‐one with CS in acetic acid, benzobicyclo[2.2.2]octen‐2‐one was obtained. The reaction mechanism also was proposed. Moreover, we report the aromatization and esterification of (R)‐(?)‐carvone by CS in acetic acid. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
2.
A new method for the direct conversion of oximes into aldehydes and ketones by treatment with cerium(IV) salts is described. Cerium(IV) salts can be used as an effective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield. The solvent effects are discussed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
3.
Davir González-Calderón Carlos A. González-González Aydeé Fuentes-Benítez Erick Cuevas-Yáñez David Corona-Becerril Carlos González-Romero 《Tetrahedron letters》2013
Tetrahydropyranyl (THP), methoxymethyl (MOM), and benzyloxymethyl (BOM) phenyl/alkyl ethers were efficiently cleaved to the corresponding parent hydroxyl compounds in good yields using catalytic amounts of Ce(SO4)2·4H2O by microwave-assisted or conventional heating in methanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of THP ethers in the presence of triisopropylsilyl (TIPS) and tert-butyldiphenylsilyl (TBDPS) phenyl ethers. 相似文献
4.
硫酸高铈催化炔烃的水合反应研究 总被引:1,自引:0,他引:1
炔烃经水合反应生成酮是有机合成中最重要和最基本的进行官能团转换的方法之一. 我们提供了一种价廉且具有高选择性的硫酸高铈催化炔烃水合方法. 实验结果表明: 在硫酸高铈(0.1 mmol)、浓硫酸(0.06 mL)、水(0.02 mL)和苯(5 mL)且反应温度为70 ℃的反应条件下, 炔烃(1 mmol)可以顺利发生水合反应生成酮. 相似文献
5.
An efficient method has been developed for the synthesis of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-naphthols promoted by NaBr/K2S2O8/Ce(NH4)2(NO3)6. Using this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields (17 examples, 70–92% yields). The reactions may proceed through the following steps: bromination of 2-naphthols by in-situ-generated bromine from NaBr and K2S2O8 to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-2-ols with anilines to afford the corresponding amines, and subsequent oxidation of the amines into the products by Ce(NH4)2(NO3)6. These newly obtained α-imine ketones have great potentials for synthesis of special optical materials bearing naphthalene moiety. 相似文献
6.
Single crystals of Sr[B(C6H5O7)2](H2O)4 · 3H2O, a new borate‐citrate material, were grown with sizes up to 8 × 6 × 2 mm by slow evaporation of water at room temperature. The structure of Sr[B(C6H5O7)2](H2O)4 · 3H2O was determined by single‐crystal X‐ray diffraction. It crystallizes in the monoclinic space group P21/c, with a = 11.363(3) Å, b = 18.829(4) Å, c = 11.976(3) Å, β = 110.736(3)°, and Z = 4. The SrO8 dodecahedra, BO4 tetrahedra and citrate groups are linked together to form chains. The compound was characterized by IR and UV/Vis/NIR transmittance spectroscopy as well as thermal analysis. 相似文献
7.
Single Crystals of the Cerium(IV) Oxotellurate(IV) CeTe2O6 Orange‐red, coffin‐shaped single crystals of CeTe2O6 (monoclinic, P21/n; a = 703.71(5), b = 1106.32(8), c = 735.24(5) pm, β = 108.066(6)°; Z = 4) were obtained by the reaction of admixtures of cerium dioxide and tellurium dioxide (CeO2, TeO2; molar ratio 1 : 2) in the presence of fluxing CsCl (750 °C, 4 d) in evacuated silica tubes. The crystal structure contains eightfold coordinated Ce4+ cations, which are surrounded by irregular trigonal dodecahedra of oxygen atoms. The interconnection of these [CeO8] polyhedra occurs via two edges (O2–O2′ and O3–O3′) with equatorial orientation relative to each other forming zigzag chains {[CeO4/1O4/2]8–} which run parallel to [100] and arrange as a hexagonal packing of rods. Both crystallographically different Te4+ cations exhibit trigonal non‐planar coordination figures (ψ1 tetrahedra) with three oxygen atoms each as a result of the stereochemical activity of the non‐binding electron pairs (“lone pairs”). They also are responsible for the necessary cross‐linkage of the anionic {[CeO6]8–} chains. The isotypical relationship with Ce(SeO3)2 therefore justifies the formulation Ce(TeO3)2 for CeTe2O6. 相似文献
8.
The oxidation of a range of alcohols to ketones or carboxylic acids proceeds in good yield using catalytic quantities of cerium(IV) phosphonate modified silica and sodium bromate as the re-oxidant. 相似文献
9.
合成了两种固态稀土丙氨酸配合物[Ho2(Ala)4(H2O)8]Cl6和[ErY(Ala)4(H2O)8](ClO4)6 (Ala为丙氨酸),用量热和热分析方法研究了这两种配合物的热力学性质.用全自动高精密绝热量热计测定了在78~377 K温区内的低温热容.对于[Ho2(Ala)4(H2O)8]Cl6,在214~255 K温区内发现一固-固相变,其相变温度为235.09 K.对于[ErY(Ala)4(H2O)8](ClO4)6,在99~121 K温区内也发现一固-固相变,其相变温度为115.78 K. [Ho2(Ala)4(H2O)8]Cl6固-固相变焓为3.02 kJ• mol-1,相变熵为12.83 J•K-1•mol-1; [ErY(Ala)4(H2O)8](ClO4)6 固-固相变焓为1.96 kJ•mol-1,相变熵为16.90 J•K-1•mol-1.同时,用TG技术在40~800 ℃温区研究了两配合物的热稳定性.由TG/DTG曲线分析可知, [Ho2(Ala)4(H2O)8]Cl6从80 ℃到479 ℃热分解分两步完成, [ErY(Ala)4(H2O)8](ClO4)6从120 ℃到430 ℃热分解分三步完成. 相似文献
10.
Low-temperature heat capacities of the compound Ni(C4H7O5)2·2H2O(S) have been measured with an auto- mated adiabatic calorimeter. A thermal decomposition or dehydration occurred in 350--369 K. The temperature, the enthalpy and entropy of the dehydration were determined to be (368.141 ±0.095) K, (18.809±0.088) kJ·mol ^-1 and (51.093±0.239) J·K^-1·mol^-1 respertively. The experimental values of the molar heat capacities in the temperature regions of 78-350 and 368-390 K were fitted to two polynomial equations of heat capacities (Cp,m) with the reduced temperatures (X), [X=f(T)], by a least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated on the basis of the fitted polynomials. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K. 相似文献
11.
搅拌釜中制备草酸铈的团聚尺寸模型研究 总被引:6,自引:0,他引:6
以硝酸铈和草酸铵反应生成草酸铈沉淀为研究对象,探讨了搅拌釜中输入功率、溶液过饱和度与产物团聚尺寸之间的变化关系并在团聚和破碎动力学的基础上建立了团聚尺寸模型。根据草酸铈沉淀实验中得到的实验结果求得了一定反应体系浓度下的模型K1,K2和K3值,最后通过-↑LtE,max的模型计算值与实验值,ε--↑LtE的模型曲线与实验曲线的比较初步证明了该模型的实际适用性。 相似文献
12.
Novel Halogenochalcogeno(IV) Acids: [H3O(Benzo‐18‐Crown‐6)]2[Te2Br10] and [H5O2(Dibenzo‐24‐Crown‐8)]2[Te2Br10] Systematic studies on halogenochalcogeno(IV) acids containing tellurium and bromine led to the new crystalline phases [H3O(Benzo‐18‐Crown‐6)]2[Te2Br10] ( 1 ) and [H5O2(Dibenzo‐24‐Crown‐8)]2[Te2Br10] ( 2 ). The [Te2Br10]2‐ anions consists of two edge‐sharing distorted TeBr6 octahedra, the oxonium cations are stabilized by crownether. ( 1 ) crystallizes in the monoclinic space group P21/n with a = 14.520(5) Å, b = 22.259(6) Å, c = 16.053(5) Å, β = 97.76(3)° and Z = 4, whereas ( 2 ) crystallizes in the triclinic space group with a = 11.005(4) Å, b = 12.103(5) Å, c = 14.951(6) Å, α = 71.61(3)°, β = 69.17(3)°, γ = 68.40(3)° and Z = 1. 相似文献
13.
The crystal structures of Na2Mg3(OH)2(SO4)3 · 4H2O and K2Mg3(OH)2(SO4)3 · 2H2O, were determined from conventional laboratory X‐ray powder diffraction data. Synthesis and crystal growth were made by mixing alkali metal sulfate, magnesium sulfate hydrate, and magnesium oxide with small amounts of water followed by heating at 150 °C. The compounds crystallize in space group Cmc21 (No. 36) with lattice parameters of a = 19.7351(3), b = 7.2228(2), c = 10.0285(2) Å for the sodium and a = 17.9427(2), b = 7.5184(1), c = 9.7945(1) Å for the potassium sample. The crystal structure consists of a linked MgO6–SO4 layered network, where the space between the layers is filled with either potassium (K+) or Na+‐2H2O units. The potassium‐bearing structure is isostructural to K2Co3(OH)2(SO4)3 · 2(H2O). The sodium compound has a similar crystal structure, where the bigger potassium ion is replaced by sodium ions and twice as many water molecules. Geometry optimization of the hydrogen positions were made with an empirical energy code. 相似文献
14.
K. G. Varshney A. Agrawal S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2005,81(1):183-189
Summary Pectin based cerium (IV) and thorium (IV) phosphates have been synthesized as new phases of hybrid fibrous ion exchangers. Both materials were characterized using X-ray diffraction, infrared (IR) spectra, thermogravimetric analysis (TG), differntial thermogravimetry (DTG), differntial thermal analysis (DTA) and scanning electron microscopy (SEM), as well as the determination of their ion exchange capacity, elution and pH titration. The X-ray study reveals the amorphous nature of the materials, while SEM studies confirm the fibrous nature of the materials. The thermal studies of these materials indicate that both of them are highly stable on heating as they retain about 97% of their ion-exchange capacity (i.e.c.) on heating up to 100°C and about 81% on heating up to 200°C. 相似文献
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《Magnetic resonance in chemistry : MRC》2002,40(4):289-292
The 17O NMR spectra of 17O isotope‐enriched tributyltin(IV) acetate (1) and dibutyltin(IV) diacetate (2) were recorded in various solvents over wide temperature ranges. Only a single 17O signal was observed for both oxygen atoms of the —COOSn—groups under these experimental conditions, in both non‐coordinating and coordinating solvents. The 17O NMR spectra of tert‐butyl acetate (3) were obtained for comparison. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
18.
The adsorption and decomposition of H2O on GaN(0001) surface have been explored employing density functional theory (DFT). Two distinct adsorption features of H2O on GaN(0001) corresponding to molecular adsorption and H-OH dissociative adsorption are revealed by our calculations. The activities of the surface reactions of H2O on GaN(0001) surface are investigated. For the stepwise processes of H2O decomposition into H2 in gas phase and adsorbed O atom (H2O(g)→H2O(chem)→OH(chem) + H(chem)→2H(chem) + O(chem)→H2(g) + O(chem)), the first and second steps are facile and can even occur at room temperature; while the last two have high barriers and thus are difficult to proceed, especially the fourth step is endothermic. In short, H2O adsorption and decomposition into H2 in gas phase and adsorbed O atom on GaN(0001) surface are exothermic by -43.98 kcal/mol. 相似文献
19.
Theoretical investigation of the structures and spectroscopic properties of (H2O4)n (n = 1–4) clusters 下载免费PDF全文
Hong‐Dal Kim Hyun‐Il Seo Hui‐Seong Song Seung‐Joon Kim 《International journal of quantum chemistry》2016,116(19):1427-1436
Density functional theory and ab initio calculations were performed to elucidate the hydrogen interactions in (H2O4)n (n = 1–4) clusters. The optimized geometries, binding energies, and harmonic vibrational frequencies were predicted at various levels of theory. The trans conformer of the H2O4 monomer was predicted to be the most stable structure at the CCSD(T)/aug‐cc‐pVTZ level of theory. The binding energies per H2O4 monomer increased in absolute value by 9.0, 10.1, and 11.8 kcal/mol from n = 2 to n = 4 at the MP2/cc‐pVTZ level of theory (after the zero‐point vibrational energy and basis set superposition error corrections). This result implies that the intermolecular hydrogen bonds were stronger in the long‐chain clusters, that is, the formation of the longer chain in the (H2O4)n clusters was more energetically favorable. 相似文献
20.
Saturating solid phases, Ce2(SO4)3·hH2O, with hydrate numbers h equal to 12, 9, 8, 5, 4 and 2, have been identified by critical evaluation of the solubility data
in the system Ce2(SO4)3—H2O over the temperature range 273–373 K. The results are compared with the respective TG—DTA—DSC and X-ray data. The solubility
smoothing equations, transition points and solution enthalpy estimators of the identified hydrates are given. The stable equilibrium
solid phases are concluded to be only Ce2(SO4)3·9H2O at 273–310 K, Ce2(SO4)3·4H2O at 310–367 K and Ce2(SO4)3·2H2O at 367–373 K. Divergencies of up to 185% in the reported solubility data are mainly due to a variety of metastable equilibria
involved in the close crystallization fields, and incorrect assignments of the saturating solid phases. Since a similar variety
of the hydrate numbers exists for the analogous La(III) system, it most probably also occurs for the corresponding Pu(III),
Np(III) and U(III) systems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献