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1.
本文在研究Mo(W)-Cu(Ag)-S原子簇化合物的低热固态合成化学基础上,详细地对该类簇合物进行了归纳,从中提出:1.(M=Mo,W;n=2,3,4)作为配体中心.2.氧原子在簇合物中仅作为端基,不参与同其他金属成键.3.单个MS4(M=Mo,W)基团最多只能键合六个Cu(Ag)原子,即最大核数为七.4.迄今为止所有Mo(W)-Cu-S原子簇化合物中Cu均为+1价.5.预计合低价态Mo(W)的这类簇合物将会有很大进展.  相似文献   

2.
合成了一系列结构为层状ABO3的复合氧化物La4BaCu5-xMxO13(M=Mn,Co),并利用XRD、X射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。XRD分析结果表明:它们的结构为五层的ABO3结构。活性氧种的研究表明La4BaCu5O13中掺杂Mn或Co之后,样品中明显存在的MCu(M=Mn,Co)之间的协同作用,并且CuMn之间协同作用明显比CuCo的强。  相似文献   

3.
CuZSM-5分子筛上苯酚羟化制苯二酚   总被引:4,自引:0,他引:4  
在Na2O-SiO2-CuO-H2O体系中以15%TPABr-85%HMDA为模板剂合成了CuZSM-5分子筛,并用XRD,IR及SEM等方法进行了表征,考察了CuZSM-5分子筛催化苯酚与过氧化氢的羟化活性,研究了催化剂用量、反应温度、反应时间及n(PhOH)/n(H2O2)等对羟化活性的影响.  相似文献   

4.
合成了一系列结构为层磁状ABO3的复合氧化物La4BaCu5-xMxO13(M=Mn,Co),并利用XRD、X射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。XRD分析结果表明:它们的结构为五层的ABO3结构。玫瑰中a4BaCu5O13中掺Mn或Co之后,样品中明显存在的M-Cu(M=Mn,Co)之间的协同作用,并且Co-Mn之间协同作用明显比Cu-Co的强。  相似文献   

5.
钕, 铈掺杂的正极材料尖晶石型LiMn2O4的制备及性能   总被引:6,自引:0,他引:6  
通过掺杂不同含量的Nd,Ce制备LiMn2-xRExO4(RE=Ce,Nd;x=0,0.05,0.1,0.15,0.2)锂离子电池正极材料,研究稀土元素拓杂对尖晶石LiMn2O4正极材料电化学性质的影响。掺杂Nd,Ce后LiMn2O4正极材料更适合于锂离子的嵌入和脱出,电池的循环性能提高,但充放电容量随掺杂量的增加而下降。X射线光电子能谱分析表明掺杂Nd,Ce的LiMn2O4正极材料,其Mn^4+  相似文献   

6.
锂离子电池阴极材料尖晶石结构Li1+xMn2—xO4的研究   总被引:29,自引:1,他引:29  
吴晓梅  杨清河 《电化学》1998,4(4):365-371
本文报导尖晶石结构阴极材料Li1+xMn2-xO4(O<x<1)的制备方法,讨论温度及原料对合成材料的电化学特性的影响,用电化学及结构化学理论研究了化学计量尖晶石结构LiMn2O4中,过量锂占据晶格中锰的位置,对电池初始容量及循环寿命产生的影响.  相似文献   

7.
李彬  白玉白 《应用化学》1994,11(1):67-71
以Mg(NO3)2,Ca(NO3)2,Eu(NO3)3,Bi(NO3)3和Si(OC2H5)4为反应物,采用溶胶-凝胶法,在比较低的温度,首次合成0.701molMgO-0.175molCaO-1.25molSiO2:0.06molEu^3+,0.002molBi^3+(加入Li^+作为电荷补偿剂)发光体,得到了最佳合成条件,研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程,探讨了发光体在不同激光  相似文献   

8.
研究了热环境对Cu-Mn-Ce-O催化剂表面积、结构、氧性能及对甲苯催化氧化活性的影响。发现CeO2作为助催化剂,对延缓氧化铝载体的表面收缩几乎没有作用,但能阻止催化剂中CuMn2O4尖晶石的生成,防止无定型活性相在高温环境中的烧结,提高催化剂水热稳定性能,尤其在温度高于800℃时,效果尤佳,合适的Ce/Cu原子比为0.38~0.44。  相似文献   

9.
CuY和Cu-ZSM-5催化剂上NO直接分解活性及活性中心的研究   总被引:2,自引:0,他引:2  
研究了CuY,Cu-ZSM-5分子筛制备条件对NO直接分解活性的影响.结果表明,在不同酸碱度下交换的CuY分子筛,在pH=9时活性较好,而Cu-ZSM-5型在pH=7时较好.随交换度提高,Cu-ZSM-5活性上升,而CuY交换度达45%后活性趋于平稳:用DTA,TPD,XPS及IR等技术,对活性中心进行了研究,表明钢是以水合离子形式与分子筛中Na+进行交换.Cu-ZSM-5的活性位单一,CuY上则有两种NO吸附位.经400℃焙烧后,铜优先占据Y的β笼,此即活性位.未经焙烧的样品中铜主要以Cu2+存在.400℃抽空处理产生Cu+.讨论了NO在含铜样品表面的反应过程.  相似文献   

10.
MoO_2Br_2体系催化丁二烯聚合中烯丙基卤素的作用   总被引:2,自引:0,他引:2  
MoO2Br2-Al(i-Bu)2OPhCH3(-m)体系催化丁二烯1,2-聚合过程中添加C3H5X(X=Cl、Br和I)对聚合物分子量有较好的调节作用,其中以C3H5Br的调节作用最强,Mn从17.5×105降至3.5×105,但对催化活性有一定的影响.在测定催化体系的UV光谱、(13)C-NMR谱、聚合活性和聚合动力学参数的基础上,讨论了C3H5X在催化体系中的行为.  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

13.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

14.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

15.
16.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

17.
Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.  相似文献   

18.
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.  相似文献   

19.
A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).  相似文献   

20.
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.  相似文献   

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