共查询到20条相似文献,搜索用时 15 毫秒
1.
Roberta Bernini Enrico Mincione Maurizio Barontini Giancarlo Fabrizi Sabrina Tempesta 《Tetrahedron》2006,62(33):7733-7737
Alkylated phenol and methoxytoluene derivatives were catalytically and selectively oxidized to the corresponding 1,4-benzoquinones in good conversions and yields. Reactions were performed with hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3) in 1-butyl-3-methylimidazolium tetrafluoroborate [bmim]BF4, a neutral ionic liquid. Compounds were tested in vitro for their antifungal activity against the growth of several widespread soil fungi. Some of them were proved to be potent inhibitors of Fusarium sp. than ketoconazole, a commercially available and expensive antifungal agent. 相似文献
2.
A convenient and efficient application of hydrogen peroxide/methyltrioxorhenium in ionic liquids [bmim]BF4 and [bmim]PF6 for the oxidation of hydroxylated and methoxylated benzaldehydes and acetophenones to the corresponding phenols is described. Good yields of products were obtained in short reaction times. 相似文献
3.
采用G3B3方法构建反式2-甲基-2-丁烯酸甲酯与O3反应体系以及后续Criegee自由基有、无水分子参与下异构化反应的势能面剖面.结果表明,反式2-甲基-2-丁烯酸甲酯与O3反应首先生成一个稳定的五元环中间体,此中间体按断键位置不同后续裂解反应存在两条路径,分别生成产物P1(CH3CHOO+CH3OC(O)C(CH3)O)和P2(CH3CHO+CH3OC(O)C(CH3)OO).利用经典过渡态理论(TST)并结合Wigner矫正模型计算了200-1200 K温度区间内标题反应的速率常数kTST/W.计算结果显示,294 K时,该反应速率常数为7.55×10-18cm3molecule-1s-1,与Bernard等对类似反应所测实验值非常接近.生成的Criegee自由基(CH3CHOO和CH3OC(O)C(CH3)OO)可分别与水分子发生α-加成及β-氢迁移反应,其中Criegee自由基与水的α-加成反应较其与水的β-氢迁移反应具有优势.另外与无水分子参与CH3CHOO和CH3OC(O)C(CH3)OO异构化反应相比,水分子的参与使得异构化反应较为容易进行. 相似文献
4.
采用溶剂热法-旋涂法构建了Sb2O3/BiVO4/WO3半导体异质结,并采用X射线衍射、扫描电子显微镜、X射线光电子能谱等手段表征了其物化性质。在1.23 V(vs RHE)电位下,BiVO4/WO3的光电流密度相对于BiVO4提高了2倍。进一步复合Sb2O3之后,虽然Sb2O3/BiVO4/WO3薄膜的光电流密度有所下降,但其光电催化产H2O2的法拉第效率和产生速率得到明显提升。在1.89V(vs RHE)电位下,3c-Sb2O3/BiVO4/WO3薄膜产H2O2的法拉第效率提高到约19%;1c-Sb2O 相似文献
5.
采用溶剂热法-旋涂法构建了Sb2O3/BiVO4/WO3半导体异质结,并采用X射线衍射、扫描电子显微镜、X射线光电子能谱等手段表征了其物化性质。在1.23 V(vs RHE)电位下,BiVO4/WO3的光电流密度相对于BiVO4提高了2倍。进一步复合Sb2O3之后,虽然Sb2O3/BiVO4/WO3薄膜的光电流密度有所下降,但其光电催化产H2O2的法拉第效率和产生速率得到明显提升。在1.89V(vs RHE)电位下,3c-Sb2O3/BiVO4/WO3薄膜产 H2O2的法拉第效率提高到约 19%;1c-Sb2O3/BiVO4/WO3薄膜 H2O2产生速率从约2.1 μmol·h-1·cm-2提高到约3.6 μmol·h-1·cm-2。此外,Sb2O3的复合显著提高了BiVO4/WO3电极材料的光电催化稳定性。 相似文献
6.
合成了稀土(钬, Ho)-氨基酸(甘氨酸, C2H5O2N)二元配合物Ho(NO3)3(C2H5O2N)4·H2O, 并且通过化学分析、元素分析和红外(IR)光谱对配合物进行了表征. 用高精度全自动绝热量热仪, 测定了该配合物在80-390 K温度区间的定压摩尔热容(Cp,m). 利用实验测定的热容数据, 采用最小二乘法, 将热容曲线上热容峰以外的两段平滑区的摩尔热容对折合温度进行拟合, 建立了热容随折合温度变化的多项式方程. 根据热容与焓、熵的热力学关系,计算出了配合物在80-390 K温度区间内,每隔5 K,相对于298.15 K的摩尔热力学函数(HT,m-H298.15,m)和(ST,m-S298.15,m). 通过热容曲线分析, 计算出了350 K附近转变过程的焓变(ΔtrsHm)和熵变(ΔtrsSm). 用差示扫描量热法(DSC)测定了配合物的热稳定性. 相似文献
7.
卟啉H2TSPP和Ag(II)TSPP吸附在均分散Fe3O4胶体上的拉曼光谱 总被引:5,自引:0,他引:5
Surface Enhanced Raman Scattering (SERS) of tetrasodium meso-tetrakis (4-sulfonatophenyl) porphine (H2TSPP) and silver tetraphenylporphyrin (Ag(Ⅱ)TSPP) adsorbed spontaneously on uniform Fe3O4 colloids are recorded. The enhancement of Raman bands is approximately 30. An analysis of the SERS spectrum shows that on the Fe3O4 surface H2TSPP takes its diacid form H42+TSPP. 相似文献
8.
通过恒电势电沉积和加热处理在泡沫镍基体上制备了Co3O4纳米片. 利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段对纳米片的形貌和结构进行了表征. 采用线性伏安扫描和计时电流技术研究了Co3O4纳米片电极对H2O2的电还原性能. 结果表明,在3.0 mol/L KOH 和 0.4 mol/L H2O2溶液中,当电压为-0.4 V(vs. Ag/AgCl)时,线性伏安扫描电流密度达到-0.386 A/cm2,在1000 s 测试时间内,计时电流密度衰减很小,表明Co3O4纳米片电极对H2O2具有很高的活性和稳定性. 相似文献
9.
采用密度泛函理论(DFT)研究了螺桨烷型分子BX[(CH2)n]3和BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的结构、稳定性、化学键和电子光谱性质.计算结果表明这些分子都是稳定的.BX[(CH2)n]3(X=N,P;n=1-6)的最高占据分子轨道(HOMO)和最低空分子轨道(LUMO)之间的能隙均大于5.20 eV,其中BN[CH2]3和BP[CH2]3的能隙超过7.0 eV,与C5H6的能隙(7.27 eV)很接近,BX(CH2)[CH(CH2)n CH](X=N,P;n=1-6)的能隙在6.80 eV左右.所研究分子能量的二阶差分表明BN[(CH2)3]3、BP[(CH2)4]3及BX(CH2)[CH(CH2)2CH](X=N,P)是最稳定的.BX[(CH2)n]3的Wiberg键级表明除了BN[(CH2)n]3(n=2和6)中不存在B―N键,其它化合物中B和N均形成了化学键,BP[(CH2)n]3中除了BP[(CH2)2]3不存在B―P键,其它的均存在.电子密度的拓扑分析表明N―B键属于离子键,而P―B键具有共价键特征.BX[(CH2)n]3(X=N,P)的第一垂直激发能分别在191.1-284.8 nm和191.8-270.1 nm之间,BX(CH2)[CH(CH2)n CH](X=N,P)的第一垂直激发能分别在190.5-199.7 nm和209.0-221.3 nm之间. 相似文献
10.
通过调节B2O3-Bi2O3-ZnO-Al2O3(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO3)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明:添加适量的BBZA玻璃能够有效地将BaTiO3陶瓷烧结温度由1 350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO3的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO3陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO3晶粒表面。优化的BaTiO3陶瓷制备条件如下:BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO3陶瓷介电常数达到1 364,介电损耗低至1.2%。 相似文献
11.
通过调节B2O3‐Bi2O3‐ZnO‐Al2O3(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO3)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明:添加适量的BBZA玻璃能够有效地将BaTiO3陶瓷烧结温度由1350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO3的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO3陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO3晶粒表面。优化的BaTiO3陶瓷制备条件如下:BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO3陶瓷介电常数达到1364,介电损耗低至1.2%。 相似文献
12.
Hyunsoo Park 《Journal of solid state chemistry》2004,177(1):159-164
The compound previously reported as Ba2Ti2B2O9 has been reformulated as Ba3Ti3B2O12, or Ba3Ti3O6(BO3)2, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO3:BaTiB2O6 (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F2)=0.039 for 504 unique reflections. Ba3Ti3O6(BO3)2 is isostructural with K3Ta3O6(BO3)2. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba3Ti3O6(BO3)2 is equal to 95% of that of LiNbO3. 相似文献
13.
通过溶胶和超临界干燥方法制得了Fe2O3/Al2O3二元气凝胶,其比表面积和孔隙体积分别为246 m2·g-1和1.89 cm3·g-1,并具有较宽的孔径分布。以Fe2O3/Al2O3二元气凝胶作催化剂,通过甲烷催化裂解成功地合成了高质量的单壁纳米碳管。利用FESEM、TEM和HRTEM、Raman光谱等分析手段研究了反应温度对单壁纳米碳管生长的影响。结果表明在900 ℃时合成单壁纳米碳管的质量较高,并且合成的炭产物为毡状,该炭产物主要为高质量的单壁纳米碳管。 相似文献
14.
F. M. Bautista J. M. Campelo A. Garcia D. Luna J. M. Marinas A. A. Romero 《Reaction Kinetics and Catalysis Letters》1998,63(2):261-269
The vapor-phase catalytic alkylation of phenol with dimethyl carbonate over different AlPO4 (Al/P=1), Al2O3 and AlPO4-Al2O3 (5–25 wt.% Al2O3) catalysts produces anisole (O-alkylation) as the major reaction product althougho-cresol (C-alkylation) and methylanisoles were also found. The reaction is first order in phenol while O-and C-alkylation
follow parallel processes. As compared with methanol, DMC is far more effective as a methylating agent, and the methylation
proceeds at a lower temperature and with higher O-alkylation selectivity. 相似文献
15.
Mahboubeh RostamiAhmad R. Khosropour Valiollah MirkhaniMajid Moghadam Shahram TangestaninejadIraj Mohammadpoor-Baltork 《Tetrahedron letters》2011,52(52):7149-7152
A rapid and simple procedure for the synthesis of the indenone derivatives, N-(1-oxo-1H-inden-2-yl)benzamides, via intramolecular Friedel-Crafts (IFC) reaction of (Z)-4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) catalyzed by H3PW12O40 supported on neutral alumina under microwave irradiation has been developed. The reaction is straightforward and allows easy isolation of the product. The catalyst could be re-used up to four times after simple filtration. 相似文献
16.
Roberta Bernini Antonietta CorattiGiancarlo Fabrizi Antonella Goggiamani 《Tetrahedron letters》2003,44(50):8991-8994
The Baeyer-Villiger oxidation of cyclic ketones can be effected by methyltrioxorhenium/hydrogen peroxide in the ionic liquid [bmim]BF4. After simple extraction of the lactone with diethyl ether, the catalyst can be repeatedly recycled and efficiently reused for the lactonisation process in the same reaction medium. 相似文献
17.
La2O3对Ni/γ-Al2O3甲烷化催化剂的助催化作用 总被引:14,自引:0,他引:14
我国将稀土作为助剂引入镍基甲烷化催化剂,大大提高了催化剂的活性和热稳定性,并已投入工业应用[1-3].稀土对不同镍催化剂反应性能及其作用机理的研究已有一些报导[3-7].谢有畅等观察到镍负载在经单层La2O3改性的γ-Al2O3表面,其晶粒要比没有La2O3时小得多.Rotgerink等认为添加La后反应速率的增加不只是由于几何效应,而是La对甲烷化本身有促进作用,单位镍表面的活性是随La含量不同而改变的,活性增加的同时表观活化能也增加[5].作为助剂的La2O3在氢还原和反应过程中的变化及其作用的研究和讨论较少,目前一般认为添… 相似文献
18.
Bei-Ping Liu Zhi-Cheng Tan Xiao-Zheng LanHua-Guang Yu Da-Shun ZhangLi-Xian Sun 《Thermochimica Acta》2003,401(2):233-238
Two solid-state coordination compounds of rare earth metals with glycin, [Gd4/3Y2/3(Gly)6(H2O)4](ClO4)6·5H2O and [ErY(Gly)6(H2O)4](ClO4)6·5H2O were synthesized. The low-temperature heat capacities of the two coordination compounds were measured with an adiabatic calorimeter over the temperature range from 78 to 376 K. [Gd4/3Y2/3(Gly)6(H2O)4](ClO4)6·5H2O melted at 342.90 K, while [ErY(Gly)6(H2O)4](ClO4)6·5H2O melted at 328.79 K. The molar enthalpy and entropy of fusion for the two coordination compounds were determined to be 18.48 kJ mol−1 and 53.9 J K−1 mol−1 for [Gd4/3Y2/3(Gly)6(H2O)4](ClO4)6·5H2O, 1.82 kJ mol−1 and 5.5 J K−1 mol−1 for [ErY(Gly)6(H2O)4](ClO4)6·5H2O, respectively. Thermal decompositions of the two coordination compounds were studied through the thermogravimetry (TG). Possible mechanisms of the decompositions are discussed. 相似文献
19.
以TiCl3和InCl3为Ti源和In源,在不使用还原剂的条件下,首先通过液相沉淀反应制备前驱体沉淀,然后采用后续水热处理制备Ti3+自掺杂的TiO2(A)/TiO2(R)/In2O3纳米异质结,考察了水热处理温度对材料结构和性能的影响。利用X射线衍射、透射电子显微镜、X射线光电子能谱和紫外-可见漫反射光谱对样品进行表征。分别以罗丹明B和苯酚溶液为模拟废水评价了样品的可见光催化降解性能。结果表明,与纯的TiO2、In2O3以及Ti3+自掺杂的TiO2相比,Ti3+自掺杂的TiO2(A)/TiO2(R)/In2O3纳米异质结在可见光区有明显的吸收,并具有良好的可见光催化降解性能,200℃下水热处理24 h所得样品光催化降解罗丹明B的反应速率常数(0.0444 min-1)分别是纯TiO2和In2O3的17.76倍和8.71倍。瞬态光电流时间响应结果表明样品的光催化性能主要来源于TiO2(A)/TiO2(R)/In2O3纳米异质结导致的提高的光生电子和空穴分离效率。 相似文献
20.
In this paper, LaNi0.6Co0.4O3 (LNC) nanoparticles were synthesized by the sol–gel method, and the structure and morphology of LNC nanoparticles were characterized by X-ray diffraction spectrum, scanning electron microscopy and transmitting electron microscopy. And then, LNC was used to modify carbon paste electrode (CPE) without any adhesive to fabricate hydrogen peroxide and glucose sensor, and the results demonstrated that LNC exhibited strong electrocatalytical activity by cyclic voltammetry and amperometry. In H2O2 determination, linear response was obtained in the concentration range of 10 nM–100 μM with a detection limit of 1.0 nM. In glucose determination, there was the linear region of 0.05–200 μM with a detection limit of 8.0 nM. Compared with other reports, the proposed sensor also displayed high sensitivity toward H2O2 (1812.84 μA mM−1 cm−2) and glucose (643.0 μA mM−1 cm−2). Moreover, this prepared sensor was applied to detect glucose in blood serum and hydrogen peroxide in toothpaste samples with satisfied results, indicating its possibility in practical application. 相似文献