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1.
采用化学还原法以乙醇为溶剂在冰水浴中合成了一系列Co1-xNixB合金催化剂,研究了该系列合金不同Ni含量对NaBH4水解放氢性能的影响.X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)显示Co1-xNixB合金是纳米非晶态颗粒.放氢测试表明Co1-xNixB具有很高的催化活性.放氢速率先随着Ni含量的增加而增大,并在x=0.15时放氢速率达到最大值,然后随x值的增加而减小.298K时Co0.85Ni0.15B合金催化碱性硼氢化钠水解的最大放氢速率可达4228mL·min-1·g-1,CoB和Co0.85Ni0.15B合金催化放氢的活化能分别为34.25和31.87kJ·mol-1.因此以乙醇为溶剂合成的Co1-xNixB合金具有较高的催化活性. 相似文献
2.
本文报道簇合物(Et_4N)(MoFe_3S_4(Et_2dtc)_5)CH_3CN(1)和(MoFe_3S_4(C_5H_10NCSS)_5)CH_2Cl_2(2)在室温和液氮温度(77K)测试的ESR谱。在77K簇合物(1)和(2)的ESR谱分别解释为来自具有双量子跃迁(△W=2hv_0)的S=1和菱形对称的S=1/2的自旋体系,基态自旋S值与根据反铁磁性自旋耦合模型和9N—L规则计算结果一致。 簇合物(1)出现gx=gy=gz=(15/7)g_0≈4.3(E》g_0βH,D≈0)的ESR谱可以确认为Fe~(2+)碎片信号,而具有~(95,97)Mo特征超精细结构(a_0(1)≈38G)的g_0(1)=1.9735±0.0002信号来自Mo~(5+)碎片。簇合物(2)亦出现Mo~(5+)碎片信号(g_(2)=1.9748±0.0002,a_0(2)≈38G)。上述事实说明在分子内发生Fe~(2+)→Mo~(6+)净电子密度转移自氧化还原作用,选种电子非定域化有利于簇骼的形成与稳定。 相似文献
3.
用密度泛函理论PBE0法计算配合物[Fe(CO)x(Ph2Ppy)y(HgCl2)z](1: x=4, y=1, z=0; 2: x=3, y=2, z=0; 3: x=4, y=1, z=1; 4: x=3, y=2, z=1; 5: x=4, y=1, z=2; 6: x=3, y=2, z=2)的几何构型, 用PBE0-GIAO法计算配合物1~6的31P化学位移. 计算结果表明, 含2个Ph2Ppy的配合物5和6的Fe—Hg相互作用略大于含单个Ph2Ppy的配合物3和4. 含2个HgCl2的配合物4和6存在Fe—Hg σ键, 比含单个HgCl2的配合物3和5的Fe—Hg相互作用强, 配合物3和5的Fe—Hg相互作用以Fe→Hg和Fe←Hg离域为主. 配合物3中Fe的负电荷比5的小, 故配合物5的Fe—Hg相互作用比配合物3的强且Fe→Hg离域比较显著, 而配合物3的Fe←Hg离域更显著. Fe—Hg相互作用增大了双核配合物中P核周围的电子密度, 其31P化学位移比相应的单核配合物小, 且含2个HgCl2的双核配合物的31P化学位移更小. 含单个Ph2Ppy的配合物的31P化学位移小于含2个Ph2Ppy的配合物. 相似文献
4.
采用固溶烧结法制备了Mg_2Ni_(1-x)Co_x(x=0.10,0.15,0.20)合金,利用X射线衍射仪和压力-组成-温度测试仪等研究了Co含量对合金相结构和储氢性能的影响.结果表明,合金由Mg_2Ni型Mg_2(Ni,Co)主相及少量Mg和Mg Ni3Co新相组成.Mg2(Ni,Co)具有良好的可逆储氢性能,吸氢形成Mg_2Ni_(0.9)Co_(0.1)H_4型四元氢化物,其具有与父系氢化物HT-Mg_2NiH_4相近的放氢焓变(ΔHd=63.9 k J/mol H2).Mg_2Ni_(1-x)Co_x(x=0.10,0.15,0.20)合金具有良好的放氢动力学性能,二维相界面迁移为放氢过程的控制步骤.随着Co含量的增加,合金的放氢活化能(Ea)降低,其中,Mg_2Ni_(0.8)Co_(0.2)的Ea降低到54.0 k J/mol. 相似文献
5.
采用氢化燃烧法制备La2-xNixMg17(x=0.5, 1, 1.5)三元体系储氢材料, 对其热力学、动力学进行研究发现: 该体系材料具有很好的活性和较高的储氢量, 其中La1.5Ni0.5Mg17在573 K时吸放氢量分别为5.40和5.15 mass% H. 在553 K下, 体系α-β相区在600 s之内吸放氢反应分数均大于91%, 随着含Ni量的增加材料储氢容量降低, 吸放氢速率增大.物相分析知道体系吸氢后的主相是MgH2, 放氢后主相为Mg, 同时存在Mg2Ni, LaNi5或LaH3等催化物质, 从而使材料的氢化动力学性能得以明显改善. 相似文献
6.
为探究团簇Ni4P催化析氢最强的结构,基于密度泛函理论,在B3LYP/Lan12dz水平下,对团簇Ni4P的初始构型进行计算和优化,得到5种优化构型。从热力学稳定性、前线轨道图和前线轨道能级差对团簇Ni4P的析氢性能分析发现,构型1(4)和1(2)的热力学稳定性较强;团簇Ni4P各优化构型均易吸附水中的氢原子,Ni原子为团簇Ni4P催化活性位点,且构型1(4)、1(2)和2(4)催化析氢的活性更强。(1(2))-H、(2(2))-H在电化学脱附法和化学重组法中均具有较强的催化活性。以上说明构型1(2)是团簇Ni4P催化析氢最强的结构。 相似文献
7.
利用三苄基氧化锡与 2 吡咯甲酸反应 ,合成六聚体一苄基锡氧 2 吡咯甲酸酯簇合物 .通过元素分析、红外光谱、核磁共振氢谱和X射线单晶衍射对其结构进行了表征 .X射线单晶衍射测试结果表明 :化合物为三斜晶系 ,空间群P 1,a =1 2 64 4( 3 )nm ,b =1 7416( 4 )nm ,c =1 92 85 ( 4 )nm ,α =90 0 2 1( 4 )° ,β =94 5 85 ( 4 )° ,γ =90 0 2 1( 4 )° ,Z =2 ,V =4 2 3 3 0( 16)nm3 ,Dc=1 715g/cm3 ,μ =1 93 6mm-1,F( 0 0 0 ) =2 13 6,R =0 0 5 2 7,wR =0 0 70 8.该化合物为鼓型簇状结构 ,锡原子为畸变的八面体构型 . 相似文献
8.
WeiGuoCHENG XiangShengWANG GangLI XinWenGUO QingSongLIN 《中国化学快报》2005,16(1):103-106
The propylene epoxidation over TS-1/SiO2 catalyst hydrothermally treated was investigated. It was found by EPR characterization that two types of Ti (IV)-superoxide radicals,A (gz=2.0271; gy=2.0074; gx=2.0010) and B (gz=2.0247; gy= 2.0074; gx= 2.0010), were observed for TS-1/SiO2. The superoxo species A converted to B after TS-1/SiO2 catalyst was hydrothermally treated. The results show that over TS-1/SiO2 catalyst hydrothermally treated at 170℃, about 95% conversion of H2O2 with above 94% PO selectivity is obtained during continuous running for 300 h under the conditions of reaction temperature 45℃, 0.5 h^-1 WHSV of propylene. 相似文献
9.
水热合成了一种新的1-D链状四帽pseudo-Keggin结构钼钒簇合物[Ni(enMe)2]2-[Ni(enMe)2{H MoⅥ4MoⅤ4VⅣ8O40(VⅤO4)}]·4H2O 1,X-射线单晶结构分析表明,该晶体属单斜晶系,C2/c空间群.晶体学参数为a=26.3006(6),b=13.6195(3),c=19.7122(5)A,β=105.8330(10)°,V=6793.0(3)A3,Z=4,Dc=2.566 g/cm3,Mr=2623.96,μ=3.507 mm-1,F(000)=5088,R=0.0700,wR=O.1529,S=1.019.该簇合物是由金属配位桥Ni(enMe)2桥联四帽pseudo-Keggin结构(HMoⅥ4MoⅤ4VⅣ8O40(VⅤO4)}簇构成一维链状结构,链与链间通过与另外一个配位阳离子[Ni(enMe)2]2+的氢键相互作用构成超分子网状结构. 相似文献
10.
在绝对乙醇介质中制备出 2个系列四硫富瓦烯四硫醇 ttftt4- ( tetrathiafulvalene tetrathiolate) Zn盐的配位高分子化合物 ,其组成分别为 [( Zn-ttftt) Mx]n( M=Mn,Co,Ni,Cu,Hg;x=0 .3,0 .4 ,0 .5 ,1 .3,0 .7)及[( Zn-ttftt) Lny]n( Ln=La,Er,y=0 .5 ;Ln=Nd,Eu,y=0 .6) .化合物在室温下均为在空气中稳定的黑色无定形粉末状固体 .用红外光谱及 X射线光电子能谱对化合物进行了表征 ,并进行了元素分析、热分析和电导率测定 . 2 5℃时 ,化合物均为典型半导体 .化合物 [( Zn-ttftt) Ni0 .5· 1 .9Et OH]n 的室温电导率高达 3.6S/cm 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.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献
13.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
14.
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
15.
Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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
16.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
17.
N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
18.
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
19.
A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
20.
A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献