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1.
采用量子化学计算方法研究了H2O2 氧化N2 生成N2O 和H2O 的机理.结果发现, H2O2 氧化N2 先通过1 个四元环过渡态形成中间体H2N2O2 分子,H2N2O2 再通过一个五元环过渡态形成N2O和H2O.根据计算得到的每步反应的活化能,得知H2O2 氧化N2 生成中间体H2N2O2 分子是整个反应的控制步骤.  相似文献   

2.
中心为氨基、末端为硝基的苯乙炔树枝状分子的合成   总被引:1,自引:0,他引:1  
将固定相合成与“收敛/发散”方法相结合,合成了第一、二代苯乙炔树枝状分子.通过Heck-Cassar-Sonogashira-Hagihara偶联反应,将其中心和末端分别修饰上供电子的氨基和拉电子的硝基,得到第一、二代中心为氨基、末端为硝基的苯乙炔树枝状分子NH2-G1-(NO2)2和NH2-G2-(NO2)4.用傅里叶变换红外光谱跟踪了整个固定相合成过程.苯乙炔树枝状分子的紫外-可见吸收光谱呈现出规律性变化.  相似文献   

3.
钾镁氯化物(硫酸盐)与脲、水体系的溶度研究   总被引:7,自引:0,他引:7  
报导了KCl-MgCl2-CO(NH2)2-H2O和K2SO4-MgSO4-CO(NH2)2-H2O两个四元体系在25℃时的溶度及其饱和溶液的折光率、密度,相应的溶度图和组成-折光率、组成-密度图.前一体系中形成3个三元化合物:MgCl2·4CO(NH2)2·2H2O、MgCl2·CO(NH2)2·4H2O和KCl·MgCl2·6H2O溶度盐份图由9支共饱线、4个四元无变点组成.四元体系的水量图、性质-组成图有类似的变化.后一体系中有2个异成份溶解化合物MgSO4·CO(NH2)2·2H2O和K2SO4·MgSO4·6H2O形成,溶度等温图由7支双饱溶度线、3个四元无变点组成.对两个体系相图的相似性和差异点进行了讨论.  相似文献   

4.
对若干线型Mo一Fe一S簇合物[Cl2FeS2MoS2FeCl2][-2](1)、[S2MoS2FeCl2]^2^-(2)、[S2MoS2Fe(SPh)2][2-](3)、[S2MoS2FeS2Fe(SPh)2][3-](4)、[S2MoS2FeS2MoS2][3-](5)、Cl2FeS2FeCl2][2-](6)、[(PhS)2FeS2Fe(SPh)2][2-](7)的红外光谱进行了研究。通过比较它们的特征频率、结构参数和金属原子的氧化态,对νMo-St、νMo-SbνFe-Sb、νFe-SPh、νFe-Cl进行了归属。并对δS-Mo-S的归属作了初步探讨。文中讨论了MoS2Fe单元中Mo原子对νFe-Sb的影响, 通过振动频率与结构关系的研究揭示其内在联系及规律性。对两条途径的亲电诱导效应进行了讨论, 并提出一个能定性标志Fe→Mo电荷迁移大小的有用参数Δν值。  相似文献   

5.
谭建华  钟顺和 《分子催化》2006,20(3):245-248
采用表面改性法制备了负载型光催化材料CeO2-TiO2/SiO2,并用X射线衍射,比表面积测定,红外光谱,程序升温还原和紫外可见漫反射光谱技术对固体材料的结构和光响应性能进行了表征.结果表明,CeO2与TiO2在材料表面存在相互修饰作用,CeO2能拓展TiO2的光响应范围,使TiO2吸光区域由紫外拓宽至可见光区,从而提高材料的光能利用率;Ti4 可以进入CeO2晶格,形成Ce-O-Ti键合,使得Ti4 平均配位数增加,同时提高了CeO2体相晶格氧的活性;TiO2有助于提高CeO2在载体表面的分散程度,减小CeO2的微晶尺寸,提高固体材料的能隙值和氧化还原能力.  相似文献   

6.
乙烷与CO2制乙烯反应的热力学和动力学研究   总被引:8,自引:0,他引:8  
乙烷与CO2的主要反应及其热力学研究表明,乙烷与CO2反应很复杂,提高CO2氧化乙烷脱氢生成乙烯的选择,关键在一催化剂的开发;CO2不但可提高乙灶脱氢制乙烯的热力学平衡转化率,而且可与催化剂表面的积碳发生反应,延长催化剂的使用寿命。研究了催化剂上乙烷与CO2制乙烯反应的动力学,确定了CO2氧化乙烷脱氢反应的动力学方程及参数,表明乙烷与CO2制乙烯的反应速度比乙烷热裂解制乙烯的反应速度要大得多。  相似文献   

7.
1. INTRODUCTION Chitin, the most abundant natural amino polysaccharide and estimated to be produced annually almost as much as cellulose, is well known to consist of 2-acetamido-2-deoxy-β-D- glucose through α, β(1→4) linkage. Chitin is the major source of surface pollution in coastalareas. Chitosan is the N-deacetylated derivative of chitin and their structures are shown in Fig. 1. Fig. 1 Structures of Chitin and Chitosan Because of the excellent properties such as biocompatibility…  相似文献   

8.
 用XRD, XPS, CO-TPR, NH3-TPD, SO2-TPD和IR等方法表征了SnO2-TiO2固溶体催化剂的物理化学性质. 不同配比的SnO2和TiO2均可形成均一的具有金红石结构的连续固溶体,其晶粒度比单纯的SnO2或TiO2的晶粒度小. SnO2-TiO2固溶体的比表面积随SnO2含量的增大呈火山形变化,说明在SnO2-TiO2固溶体中SnO2可阻止TiO2由锐钛矿型变为金红石型过程中比表面积的减小,而TiO2则提供了维持大表面的结构框架. SnO2倾向于在固溶体表面偏析,固溶体的表面氧含量高于单纯SnO2的表面氧含量而低于单纯TiO2的表面氧含量. SnO2, TiO2和SnO2-TiO2表面含有能被CO还原的吸附氧和晶格氧,被还原的SnO2, TiO2和SnO2-TiO2的表面晶格氧的数量仅占所有晶格氧的0.001%, 说明CO只使部分晶格氧还原并生成氧阴离子空穴. TiO2表面没有酸性, SnO2和SnO2-TiO2呈微弱酸性. 经CO还原的SnO2-TiO2上存在大量的强碱中心,说明SnO2和TiO2之间发生了协同作用. SnO2-TiO2固溶体的这些物化性质均十分有利于SO2+NO+CO的氧化还原反应.  相似文献   

9.
芥子气模拟剂2-氯乙基乙基硫醚的光催化降解   总被引:4,自引:0,他引:4  
利用连续流动微反、原位红外和GC/MS等手段考察了芥子气模拟剂2-氯乙基乙基硫醚(2-CEES)在P25 TiO2上的光催化降解反应,证实CO2和H2O是这个反应的最终产物.详细的跟踪分析表明,除了CO2和H2O外,在反应的气相混合物中可检测到C2H4、CH3CHO、CH4、CO、HCl和H2S;少量小分子的羧酸、醚和砜;微量C2H5SC2H5、C2H5S2C2H5、C2H5SC2H4Cl和CH2ClCH2Cl等中间产物;在反应后的催化剂表面可检测到C2H5S2C2H5、C2H5SC2H4OH、C4H9S2C2H5和C2H5S2C2H4OH、等物.根据这些结果提出了2-CEES光催化降解的反应机理,推断2-CEES的光催化降解涉及脱氯、C-S键断裂、有机硫化物光聚合和裂解等复杂过程最终转化为CO2和H2O.认为各种硫物种在表面的积聚引起了催化剂的缓慢失活.  相似文献   

10.
双氧水(H2O2)是一种重要的绿色氧化剂,广泛应用于纺织、医疗、废水处理、军事等重要领域.目前, H2O2的工业生产以蒽醌法为主,该法设备投资大、运行成本高,同时工艺涉及大量的有机溶液,活性中间体蒽醌也会发生缓慢降解,产生有毒副产物.与蒽醌法相比,通过负载型贵金属催化剂催化H2与O2反应直接合成H2O2,过程绿色环保且生产工艺简单,引起了各界广泛关注.然而,从热力学上分析, H2和O2更容易反应生成H2O, H2O2只是该反应的中间产物,会继续发生加氢和直接分解反应生成H2O,导致H2和O2的低效利用,开发高H2O2选择性且高反应效率的催化剂已成为氢氧直接合成H2O2研究的重点与难点.目前大部分研究策略旨在通过调控或影响反应中心结构、价态来抑制H2O2的副反应,进而提升H2O2的选择性和反应效率;尽管已取得了良好的进展,但仍需发展新的调控策略来满足工业应用的要求.本课题组前期研究表明,促使H2O2从催化剂上脱附可以有效地提升H2O2的选择性和产率.相比于针对反应中心的调控,不稳定的H2O2从催化剂上快速脱附同样起到抑制H2O2参与副反应的作用.为此,本文提出一种炭量可控的非均一界面改性方法,以常规的Pd/TiO2作为研究对象,借助各种结构表征,发现炭物种在TiO2表面呈非均一分散状态,而且改性对于催化剂的几何结构影响较小;另外,催化剂表面的疏水性会随着碳含量的增加而增加,导致其与H2O2间的吸附能相应变小.反应结果显示,表面非均一的炭化改性技术可以显著提升Pd/TiO2催化剂的H2O2选择性和产率.通过构效关系分析,可知这种改性技术可以保持Pd颗粒与TiO2间相互作用的同时,还可以促进H2O2的快速脱附,进而提升改性Pd/TiO2催化剂的H2O2直接合成效率.该改性方法简单、易控,可拓展应用到其他类型催化剂的H2O2直接合成性能调控与改进.  相似文献   

11.
Reaction of [RhCl(PPh3)2]2 with parahydrogen revealed that the binuclear dihydride [Rh(H)2(PPh3)2mu-Cl)2Rh(PPh3)2] and the tetrahydride complex [Rh(H)2(PPh3)2(mu-Cl)]2 are readily formed. While magnetisation transfer from free H2 into both the hydride resonances of the tetrahydride and [Rh(H)2Cl(PPh3)3] is observable, neither transfer into [Rh(H)2(PPh3)2(mu-Cl)2Rh(PPh3)2] nor transfer between the two binuclear complexes is seen. Consequently [Rh(H)2(PPh3)2(mu-Cl)]2 and [Rh(H)2(PPh3)2(mu-Cl)2Rh(PPh3)2] are not connected on the NMR timescale by simple elimination or addition of H2. The rapid exchange of free H2 into the tetrahydride proceeds via reversible halide bridge rupture and the formation of [Rh(H)2(PPh3)2(mu-Cl)RhCl(H)2(PPh3)2]. When these reactions are examined in CD2Cl2, the formation of the solvent complex [Rh(H)2(PPh3)2(mu-Cl)2Rh(CD2Cl2)(PPh3)] and the deactivation products [Rh(Cl)(H)PPh3)2(mu-Cl)(mu-H)Rh(Cl)(H)PPh3)2] and [Rh(Cl)(H)(CD2Cl2)(PPh3)(mu-Cl)(mu-H)Rh(Cl)(H)PPh3)2] is indicated. In the presence of an alkene and parahydrogen, signals corresponding to binuclear complexes of the type [Rh(H)2(PPh3)2(mu-Cl)(2)(Rh)(PPh3)(alkene)] are detected. These complexes undergo intramolecular hydride interchange in a process that is independent of the concentration of styrene and catalyst and involves halide bridge rupture, followed by rotation about the remaining Rh-Cl bridge, and bridge re-establishment. This process is facilitated by electron rich alkenes. Magnetisation transfer from the hydride ligands of these complexes into the alkyl group of the hydrogenation product is also observed. Hydrogenation is proposed to proceed via binuclear complex fragmentation and trapping of the resultant intermediate [RhCl(H)2PPh3)2] by the alkene. Studies on a number of other binuclear dihydride complexes including [(H)(Cl)Rh(PMe3)2(mu-H)(mu-Cl)Rh(CO)(PMe3)], [(H)2Rh(PMe3)2(mu-Cl)2Rh(CO)(PMe3)] and [HRh(PMe3)2(mu-H)(mu-Cl)2Rh(CO)(PMe3)] reveal that such species are able to play a similar role in hydrogenation catalysis. When the analogous iodide complexes [RhIPPh3)2]2 and [RhI(PPh3)3] are examined, [Rh(H)2(PPh3)2(mu-I)2Rh(PPh3)2], [Rh(H)2(PPh3)2(mu-I)]2 and [Rh(H)2I(PPh3)3] are observed in addition to the corresponding binuclear alkene-dihydride products. The higher initial activity of these precursors is offset by the formation of the trirhodium phosphide bridged deactivation product, [[(H)(PPh3)Rh(mu-H)(mu-I)(mu-PPh2)Rh(H)(PPh3)](mu-I)2Rh(H)2PPh3)2]  相似文献   

12.
In the quest for low-molecular-weight metal sulfur complexes that bind nitrogenase-relevant small molecules and can serve as model complexes for nitrogenase, compounds with the [Ru(PiPr(3))('N(2)Me(2)S(2)')] fragment were found ('N(2)Me(2)S(2)'(2-)=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)). This fragment enabled the synthesis of a first series of chiral metal sulfur complexes, [Ru(L)(PiPr(3))('N(2)Me(2)S(2)')] with L=N(2), N(2)H(2), N(2)H(4), and NH(3), that meet the biological constraint of forming under mild conditions. The reaction of [Ru(NCCH(3))(PiPr(3))('N(2)Me(2)S(2)')] (1) with NH(3) gave the ammonia complex [Ru(NH(3))(PiPr(3))('N(2)Me(2)S(2)')] (4), which readily exchanged NH(3) for N(2) to yield the mononuclear dinitrogen complex [Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')] (2) in almost quantitative yield. Complex 2, obtained by this new efficient synthesis, was the starting material for the synthesis of dinuclear (R,R)- and (S,S)-[micro-N(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] ((R,R)-/(S,S)-3). (Both 2 and 3 have been reported previously.) The as-yet inexplicable behavior of complex 3 to form also the R,S isomer in solution has been revealed by DFT calculations and (2)D NMR spectroscopy studies. The reaction of 1 or 2 with anhydrous hydrazine yielded the hydrazine complex [Ru(N(2)H(4))(PiPr(3))('N(2)Me(2)S(2)')] (6), which is a highly reactive intermediate. Disproportionation of 6 resulted in the formation of mononuclear diazene complexes, the ammonia complex 4, and finally the dinuclear diazene complex [micro-N(2)H(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] (5). Dinuclear complex 5 could also be obtained directly in an independent synthesis from 1 and N(2)H(2), which was generated in situ by acidolysis of K(2)N(2)(CO(2))(2). Treatment of 6 with CH(2)Cl(2), however, formed a chloromethylated diazene species [[Ru(PiPr(3))('N(2)Me(2)S(2)')]-micro-N(2)H(2)[Ru(Cl)('N(2)Me(2)S(2)CH(2)Cl')]] (9) ('N(2)Me(2)S(2)CH(2)Cl'(2-) =1,2-ethanediamine-N,N'-dimethyl-N-(2-benzenethiolate)(1-)-N'-(2-benzenechloromethylthioether)(1-)]. The molecular structures of 4, 5, and 9 were determined by X-ray crystal structure analysis, and the labile N(2)H(4) complex 6 was characterized by NMR spectroscopy.  相似文献   

13.
含有亚硫酸四氟乙二醇酯(1)的四氟乙烷磺内酯(2)与H(CF_2)_4CH_2OH和三乙胺反应可获得草酸酯(CO_2CH_2CF_2CF_2—CF_2CF_2H)_2(3)。化合物(3)生成的机理解释为由于1的破环,生成了SOF_2和(COF)_2,后者进一步与H(CF_2)_4CH_2OH反应生成3。 3与二乙胺反应生成Et_2NCOCO_2CH_2(CF_2)_4H(4)。3和4皆为新化合物。  相似文献   

14.
Based on density functional theory and generalized gradient approximation calculations, the adsorption of Co2B2 and Ni2B2 clusters on the rutile TiO2 (110) surface has been investigated utilizing periodic supercell models. Unambiguously, the results demonstrate that the hollow site turns out to be preferable for Co2B2 cluster while Ti2 site is for Ni2B2 cluster to adsorb. Orbital population analysis indicates a strong interaction between Co2B2 and O atom of TiO2 surface, which can be attributed to the overlap of Co 3d and surface O 2p orbital. Similarly, for Ni2B2 , the bonding interaction occurs mostly through the interaction of Ni 3d/4s and O 2p orbitals. Note that, there is also an interaction within the Co2B2 clusters (Ni2B2) through B 2s/2p and Co 3d orbitals (Ni 3d/4s). Moreover, orbital analysis results shows that the strong bonding between Ni2B2 and Ti2 site is due to the overlap of HOMO of Ni2B2 and d-orbital of five-coordinated titanium atoms.  相似文献   

15.
Ten polymeric silver(I) double salts containing embedded acetylenediide: [(Ag2C2)2(AgCF3CO2)9(L1)3] (1), [(Ag2C2)2(AgCF3CO2)10(L2)3]H2O (2), [(Ag2C2)(AgCF3CO2)4(L3)(H2O)]0.75 H2O (3), [(Ag2C2)(1.5)(AgCF3CO2)7(L4)2] (4), [(Ag2C2)(AgCF3CO2)7(L5)2(H2O)] (5), [(Ag2C2) (AgC2F5CO2)7(L1)3(H2O)] (6), [(Ag2C2)(AgCF3CO2)7(L1)3(H2O)]2 H2O (7), [(Ag2C2)(AgC2F5CO2)6(L3)2] (8), [(Ag2C2)2(AgC2F5CO2)12(L4)2(H2O)4]H2O (9), and [(Ag2C2)(AgCF3CO2)6(L3)2(H2O)]H2O (10) have been isolated by varying the types of betaines, the perfluorocarboxylate ligands employed, and the reaction conditions. Single-crystal X-ray analysis has shown that 1-4 all have a columnar structure composed of fused silver(I) double cages, with C2(2-) species embedded in its stem and an exterior coat comprising anionic and zwitterionic carboxylates. For 5 and 6, single silver(I) cages are linked into a beaded chain through both types of carboxylate ligands. In 7, two different coordination modes of L1 connect the silver(I) polyhedra into a chain. For 8, the mu(2)-O,O' coordination mode of L3 connects the silver(I) double cages into a chain. Compound 9 exhibits a two-dimensional architecture generated from the cross-linkage of double cages by C2F5CO2-, L4, and [Ag2(C2F5CO2)2] units. Similar to 9, 10 is also a two-dimensional structure, which is formed by connecting the chains of linked double cages through [Ag2(CF3CO2)2] bridging.  相似文献   

16.
离子型有机锡化合物的合成及其生物活性   总被引:2,自引:1,他引:1  
钟桂云  孙丽娟 《应用化学》2011,28(4):387-393
利用有机锡卤化物与有机酸在有机胺存在下反应合成了一系列离子型有机锡化合物,分子通式为[HNR3][(PhCH2)3Sn(μ2-SCH2COO)Cl]、[HNR3][Ph3Sn)3(O2CCH2CO2)2]·CH3CH2OH和[HNR3] [MeCy2ClSnO2CCH2CO2SnClCy2Me]。化合物的体外抗肿瘤、杀菌和杀螨活性测试结果表明,部分化合物具有很好的生物活性。[HNR3][(Ph3Sn)3(O2CCH2CO2)2]·CH3CH2OH和[HNR3] [MeCy2ClSnO2CCH2CO2SnClCy2Me]配合物对人肺癌细胞株A-549、结肠癌细胞株HCT-8和肝癌细胞株Bel-7402的抑制率约为90%,[HNR3][MeCy2ClSnO2CCH2CO2SnClCy2Me]配合物对小麦赤霉、番茄早疫、芦笋茎枯、苹果轮纹、花生褐斑的杀死率都为100%,配合物[HNR3] [MeCy2ClSnO2CCH2CO2SnClCy2Me]的杀螨活性致死率大于90%。  相似文献   

17.
以Marcus-Hush电子转移理论为基础,提出了用量子化学密度泛函方法研究自交换和异交换电子转移反应的理论方案.在DFTB3LYP/6-311+G(2D)水平上研究了溶液中NO2/NO2-,SO2/SO2-和ClO2/ClO2-等3个氧化-还原对的自交换以及它们之间的6个交叉电子转移反应的动力学性质,获得了与实验较为一致的结果.  相似文献   

18.
杂元素冠醚研究 Ⅶ.多硒杂冠醚及其钯配合物的合成   总被引:2,自引:0,他引:2  
李卫平  刘秀芳  徐汉生 《化学学报》1994,52(11):1082-1087
在碱性条件下,1,2-二硒杂环戊烷被硼氢化钠还原成双硒负离子,然后和二醇的二对甲苯磺酸酯或二氯化物缩合成环,得到六个二硒杂冠醚(2a,3a,4a,5a,6a,7a)和七个四硒杂冠醚(2b,3b,4b,5b,6b,7b,8b).同时,通过5a,5b与二氯化钯反应,合成了两个钯配合物,并讨论了其配位特征  相似文献   

19.
采用表面改性法制备了负载型Sn2(OMe)2Cl2/SiO2双核桥联配合物催化剂,用IR,TPD和微量反应技术研究了催化剂的表面结构、化学吸附性能和反应活性.结果表明,双核桥联配合物Sn2(OMe)2Cl2以O(Me)为桥,Cl为配体,并以Sn-O-Si形式键合到SiO2表面上;CO2与催化剂表面的金属离子Sn4+和桥基配体OMe的O2-形成桥式和甲氧碳酸酯基两种吸附态,CH3OH与催化剂表面的金属离子Sn4+仅形成一种分子吸附态;在413K以下,CO2和CH3OH在Sn2(OMe)2Cl2/SiO2催化剂表面上以近100%的选择性生成碳酸二甲酯;CO2在催化剂表面形成的甲氧碳酸酯基吸附态是生成DMC的关键物种,其与在同一活性中心的分子吸附态甲醇的反应决定了催化剂的活性和产物选择性.  相似文献   

20.
Full details on a very efficient transamination reaction for the synthesis of zwitterionic N,N-dialkyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium derivatives [C6H2(=NHR)2(=O)2] 5-16 are reported. The molecular structures of zwitterions 5 (R=CH3) in 5.H2O, 13 (R=CH2CH2OMe), 15 (R=CH2CH2NMe2), and of the parent, unsubstituted system [C6H2(=NH2)2(=O)2] 4 in 4.H2O have been established by single-crystal X-ray diffraction. This one-pot preparation can be carried out in water, MeOH, or EtOH and allows access to new zwitterions with N-substituents bearing functionalities such as -OMe (13), -OH (9-12), NR1R2 with R1 = or not equal R2 (14-16) or an alkene (8), leading to a rich coordination chemistry and allowing fine-tuning of the supramolecular arrangements in the solid state. As previously described for 15, which reacted with Zn(acac)2 to afford the octahedral Zn(II) complex [Zn[C6H2(NCH2CH2NMe2)O(O)(NHCH2CH2NMe2)]2] (20), ligands 13 and 16 with coordinating "arms" afforded with Zn(acac)2 the 2:1 adducts [Zn[C6H2(NCH2CH2X)O(=O)(NHCH2CH2NX)]2] 19 (X=OMe) and 21 (X=NHEt), with N2O4 and N4O2 donor sets around the octahedral Zn(II) center, respectively. Furthermore, zwitterions 15 and 16 reacted with ZnCl2 to give the stable, crystallographically characterized Zn(II) zwitterionic complexes [ZnCl2[C6H2(NCH2CH2NR1R2)O(=O)(NHCH2CH2NHR1R2)]] 22 (R1=R2=Me) and 23 (R1=Et, R2=H) by means of an unprecedented, tandemlike synthesis in which 1) the two pendant amino groups of the organic benzoquinonemonoimine zwitterionic precursor favor metal coordination and proton transfer and 2) the saturated linker prevents pi-conjugation between the charges. The nature of the structural arrangements in the solid state for both inorganic (20, 22, 23) and organic (5, 9, 13, and 15) molecules is determined by subtle variations in the nature of the N-substituent on the zwitterion precursor.  相似文献   

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