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71.
Kh. S. Shikhaliev A. V. Falaleev G. I. Ermolova A. S. Solov'ev 《Chemistry of Heterocyclic Compounds》2002,38(2):210-212
4,6,6-Trimethyl-1,4-dihydropyrimidines have been synthesized by condensation of 2-quinazolylguanidines with mesityl oxide. The analogous reaction with benzalacetone leads to unstable 4-methyl-6-phenyl-1,4-dihydropyrimidines, which are oxidized to the corresponding 4-methyl-6-phenylpyrimidines. 相似文献
72.
J.?R.?Tolchard J.?E.?H.?Sansom P.?R.?SlaterEmail author M.?S.?Islam 《Journal of Solid State Electrochemistry》2004,8(9):668-673
Recently, high oxide ion conduction has been observed in the apatite-type systems La9.33+x(Si/Ge)6O26+x/2, with conductivities approaching and even exceeding that of yttria-stabilized zirconia. The Ge-based phases have been reported to suffer from Ge loss and undergo irreversible structural changes on sintering at the high temperatures required to obtain dense pellets. In this paper we discuss doping studies (Ba, Bi for La) aimed at stabilizing the hexagonal apatite lattice to high temperature, and/or lowering the synthesis and sintering temperatures. The results show that doping with Ba helps to stabilize the hexagonal lattice at high temperatures, although Ge loss appears to still be a problem. Conductivity data show that, as previously reported for the Si-based systems, non-stoichiometry in the form of cation vacancies and/or oxygen excess is required to achieve high oxide ion conduction in these Ge-based systems. Neutron diffraction structural data for the fully stoichiometric phase La8Ba2Ge6O26 shows that the channel oxygen atoms show little anisotropy in their thermal displacement parameters, consistent with the low oxide ion conductivity of this phase. Bi doping is shown to lower the synthesis and sintering temperatures, although the presence of Bi means that these samples are not stable at high temperatures under reducing conditions.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, April 10–12, 2003 相似文献
73.
催化裂化USY/ZnO/Al2O3脱硫添加剂的高温水热失活 总被引:3,自引:0,他引:3
对USY/ZnO/Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察,发现老化后添加剂的脱硫性能大幅度下降.采用XRD和IR等技术对USY/ZnO/Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究.结果表明,在高温下,ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石,从而造成USY晶体结构崩塌,转变成无定形状态.在ZnO含量较高的条件下,ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应,生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构.这一方面使添加剂失去了可形成硫化物吸附中心的ZnO,另一方面破坏了硫化物的裂化活性组分USY,从而造成添加剂脱硫性能下降甚至失去脱硫活性.ZnO对USY的破坏作用主要与温度有关.在USY/ZnO/Al2O3体系中,ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离,单纯的高温条件对添加剂的破坏不显著,而水蒸气可以促进ZnO的移动,有利于ZnO与USY的接触,因此在高温和有水蒸气存
在的条件下添加剂的结构易遭到破坏. 相似文献
74.
75.
The 1,3-dipolar cycloaddition reaction of meso-tetraaryl porphyrin with 2,6-dichlorobenzonitrile oxide yielded novel isoxazoline-fused chlorins and two stereoisometric bacteriochlorins. The crystal structure of bacteriochlorin was characterized by X-ray diffraction. 相似文献
76.
1 INTRODUCTION The donor properties of pyridine N-oxide and its substituted derivatives to form metal complexes have been widely investigated[1~3]. The resulting comple- xes were used as drugs[4] and catalysts[5]. So far, there have been a few reports on the synthesis of Schiff base derived from picolinaldehyde N-oxide with se- micarbazone (PNOS Scheme 1) and its metal com- plexes. And crystal structures of the complexes of PNOS with Au(III)[6], Pd(II)[7] and Cu(II)[8] were re- … 相似文献
77.
M. R. Yaftian M. Burgard D. Matt C. Wieser C. Dieleman 《Journal of inclusion phenomena and macrocyclic chemistry》1997,27(2):127-140
The complexing, extracting and mobile carrier properties of the tetra(phosphine oxide)-calix[4]arene 1 and the hybrid diamide-di(phosphine oxide)-calix[4]arene 2 were studied. Both ligands give 1 : 1 complexes with alkali cations in THF as shown by the picrate method. 1H NMR experiments were run to follow encapsulation of sodium and potassium cations. The corresponding spectra indicate C2-symmetrical structure. The observed extraction orders of the alkali picrates were as follows K+>Rb+>Li+>Cs+>Na+ for 1 and Li+>Na+>K+>Rb++ for 2. Transport kinetics was analysed by means of a model which assumes pure diffusion and which allows the evaluation of mass transfer coefficients in all systems. These coefficients and their influences on the transport rate are discussed in terms of size of the transporting species in the liquid membrane. 相似文献
78.
导电氧化物电极上丁酸丁酯电化学合成的研究 总被引:4,自引:0,他引:4
本文研究了某些氧化物电极在不同条件下对丁醇电解直接合成丁酸丁酯的影响,并测定了这些氧化物电极上的丁醇氧化极化曲线,结果表明Ti/PbO2电极在加入SnO2,Sb2O3,PdOx中间层后,不仅电极的PbO2层不易脱落,而且使电极的电催化性能有较大的提高。 相似文献
79.
钙黄绿素蓝荧光法测定食品中的微量锌(Ⅱ) 总被引:5,自引:0,他引:5
本文研究了在CTMAB存在下,用钙黄绿素蓝荧光法测定食品中的微量锌(Ⅱ)的实验条件。在本实验条件下,Zn(Ⅱ)与钙黄绿素蓝生成1:1的配合物使钙黄绿素蓝的荧光增强,最大激发波长和最大发射波长分别为353nm和440nm。 相似文献
80.
Fadila Balegroune Pierre Braunstein Laurent Douce Yves Dusausoy Daniel Grandjean Michael Knorr Martin Strampfer 《Journal of Cluster Science》1992,3(3):275-296
The reactions of K[Fe{Si(OMe)3}(CO)3(PY)][PY=Ph2PCH2C(O)Ph, Ph2PCH2C(O)[(-C5H4)FeCp] (Cp=5-C5H5), Ph2P(CH2)2CN] with CdCl2·2.5H2O, ZnX
2 (X=Cl, I) or InCl3 afforded Fe-Cd-Fe or Fe-M(-X)2
M-Fe (M=Cd, Zn, In;X=Cl, I) and Fe-InCl2 complexes. Some of them contain an unusual and labile -2-SiO alkoxysilyl bridge which may be associated with a bridging mode for the ketophosphine ligand (first such example structurally established), thus providing original results in bimetallic chemistry on the intramolecular coordination of oxygendonor functions ofchemically different hemilabile ligands firmly attached to a neighboring metal center. The structures of the trinuclear complex (3), of the chlorobenzene solvate of the tetranuclear complex (4a·C6H5Cl) and of [mer-(OC)3{(EtO)3Si} (4e) have been determined by X-ray diffraction. Crystals of 3 are orthorhombic, space groupPbcn, witha=19.010(4),b=11.766(5),c=26.998(7)Å, andZ=4. Crystals of4a·C6H5Cl are monoclinic, space groupC2/c witha=22.455(3),b=17.680(2),c=16.627(4)Å, =90.80(4)°, andZ=4. Crystals of4e are monoclinic, space groupC2/c witha=25.392(5),b=18.554(6),c=16.28(1)Å, =120.73(3)°, andZ=4. The structures were solved using direct methods and Fourier difference techniques and refined by blocked full-matrix least squares toR=0.035 (R
w
=0.049) for 2719 observed reflections, toR=0.042 (R
w
=0.056) for 3082 observed reflections, and toR=0.057 (R
w
=0.075) for 1850 observed reflections for3, 4a·C6H5Cl and4e, respectively. The Fe-Zn complexes (9a), (9b) and (9c) were prepared and characterized by spectroscopic methods.Part 21 in the Series: Complexes with Functional Phosphines. Part 20: P. Braunstein, S. Coco Cea, A. DeCian, and J. Fischer (1992).Inorg. Chem.
31, 4203. 相似文献