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81.
3-Arylsydnone-4-carbonitrile oxides may undergo 1,3-dipolar cycloadditions with alkenes to produce the corresponding 3-aryl-4-(5-substituted-isoxazolin-3-yl)sydnones. The direct reaction of 3-arylsydone-4-carbohydroximic acid chlorides with alkenes may also give the same products, and with higher yield. 相似文献
82.
Angelika Baranowska Magdalena Siedlecka Andrzej J. Sadlej 《Theoretical chemistry accounts》2007,118(5-6):959-972
Recent studies of the perturbation-dependent basis sets have indicated the possibility of a significant reduction of the size
of the usual CGTO sets without considerable loss of accuracy in calculations of molecular electric properties. The resulting
(ZPolX) basis sets have been developed for several atoms of the first and second row of the Periodic Table. The same method
of the ZPolX basis set generation is extended for the first-row transition metals and the corresponding contracted ZPolX basis
sets of the size [6s5p3d1f] are determined for both nonrelativistic and scalar relativistic calculations. The performance
of the ZPolX basis sets is verified in calculations on the first-row transition metal oxides at the level of the ROHF, ROHF/CASPT2,
and ROHF/CCSD(T) approximations. Also the study of the dipole polarizability of TiCl4 confirms the excellent features of these very compact basis sets. The ZPolX basis sets for nonrelativistic and relativistic
calculations of molecular electric properties are available on the web page http://www.chem.uni.torun.pl/zchk/basis-sets.html. 相似文献
83.
New Oxides with the “Butterfly-Motive”: Rb6[Fe2O5] and K6[Fe2O5] Rb6[Fe2O5] and K6[Fe2O5] were obtained for the first time by annealing intimate mixtures of “Rb6CdO4” with CdO (molar ratio 1 : 1.1) and KO0.48 with CdO (molar ratio 5.9 : 1) respectively in closed Fe-cylinders. Determination and refinement of the crystalstructure confirms the space group C2/m (four-circle-diffractometer data). Rb6[Fe2O5]: Ag Kα , 720 out of 1220 Io(hkl), R = 9.68%, Rw = 6.09%; a = 718.9pm, b = 1183.1 pm, c = 695.4pm, β = 95.05°, Z = 2; K6[Fe2O5]: MoKα , 1214 Out of 12141o(hkl), R = 3.20070, Rw = 2.48%, a = 691.21 pm, b = 1142.78pm, c = 665.50pm, β = 93.82°, Z = 2. The binuclear unit [O2FeOFeO2]6? already known to be planar with oxoferrates(II) now was observed to be angular here and closely related to Na6[Be2O5]. 相似文献
84.
A constant pH precipitation method has been applied to obtain solids with Ni/Fe molar ratios of 2/1, 3/2, 1/1, 2/3, and 1/2. In all cases, a phase with the hydrotalcite‐like structure is obtained, containing NiII and FeIII in the brucite‐like layers and carbonate in the interlayer, and, for samples with a Ni/Fe molar ratio lower than 2/1, amorphous hydrated iron oxides, undetected by X‐ray diffraction, are also formed. The solids have been characterized by element chemical analysis, powder X‐ray diffraction, differential thermal analysis, thermogravimetric and differential thermogravimetric analysis, FT‐IR spectroscopy, temperature‐programmed reduction and assessment of specific surface area by nitrogen adsorption at ?196 °C. In all cases reduction leads to zero‐valent state for the metals, reduced nickel particles probably favouring reduction of FeIII species; the specific surface area increases with the iron content, probably due to the amorphous nature of the hydrated iron oxides formed. Calcination at 1200 °C in air leads to well crystallized solids, formed by NiFe2O4 spinel and, additionally, rocksalt‐type NiO for Ni/Fe ratios larger than 1/2. In this way, solids with tailored compositions of these two phases can be prepared. 相似文献
85.
纳米Y2O3/钴基合金激光熔覆层的组织 总被引:6,自引:0,他引:6
利用5 kW CO2激光器,在Ni基高温合金表面,熔覆纳米稀土氧化物(Y2O3)/钴基合金复合材料,制备了涂层.利用光学显微镜、扫描电镜及透射电镜分析了熔覆层的组织结构.结果表明: 熔覆层的主要相组成为γ-Co,ε-Co,Cr23C6和Y2O3;加入纳米Y2O3,凝固组织由细长的柱状树枝晶转变为较短的树枝晶;纳米Y2O3含量增大至1%时整个断面获得等轴晶组织;纳米Y2O3作为异质形核的核心,细化了组织;纳米Y2O3在熔覆层中分布不均匀,促进了γ-Co向ε-Co的转变;熔覆层的亚结构为堆跺层错.对熔覆层等轴组织形成机制进行了分析. 相似文献
86.
Storage-Reduction of NOx over Combined Catalysts of Pt/Ba/Al2O3-Mn/Ba/Al2O3: Carbon Monoxide as Reductant 下载免费PDF全文
Sha Deng Xuehui Li Jianhua Xiao Furong Wang Lefu Wang 《天然气化学杂志》2007,16(2):213-216
Storage-reduction of NOx by carbon monoxide was investigated over combined catalysts of Mn/Ba/Al2O3-Pt/Ba/Al2O3. Combination of Mn/Ba/Al2O3 and Pt/Ba/Al2O3 catalysts in different ways showed excellent NOx storage-reduction performance and the content of Pt could be reduced by 50%. Not only the addition of 5Mn/15Ba/Al2O3 to lPt/15Ba/Al2O3 could improve its storage ability, but also enhance the NOx conversion consequently. NOx conversion over the combined catalysts (the combined catalysts I and II) was increased under dynamic lean-rich burn conditions, the maximum NOx conversion increased from 69.4% to respectively 78.8% and 75.7% over two combined catalysts. 相似文献
87.
A convenient synthetic approach is established to prepare a new class of 1-l-α-amino acid derivatives of phospholene oxides by amination of (±)-1-chloro-2-phospholene-1-oxides with several optically pure l-α-amino acid esters. All compounds obtained as a diastereomeric mixture in good to high yields. The two diastereomers were successfully separated by column chromatography and structurally identified by their spectral analyses. 相似文献
88.
G. A. Vorob'eva S. D. Chemerisov A. V. Kozintsev Ya. S. Lebedev 《Russian Chemical Bulletin》1997,46(2):284-288
A new simple method was developed for the preparation of organometallic bi- and triradicals by the heterogeneous reaction
of γ-Al2O3 or analogous oxides with free radicals generated in solution through the interaction of 3,6-di-tert-butyl-o-benzoquinone with 3,6-di-tert-butylpyrocatechol. An explanation was offered for the plus sign of the dipoledipole coupling constant observed previously
in the ESR spectra recorded in a superstrong field at low temperatures.
Deceased.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 298–302, February, 1997. 相似文献
89.
90.
D. L. Hoang A. Dittmar M. Schneider A. Trunschke H. Lieske K. -W. Brzezinka K. Witke 《Thermochimica Acta》2003,400(1-2):153-163
CrOx/La2O3 mixed oxides, prepared by impregnating La2O3 with appropriate aqueous solutions of (NH4)2CrO4 and calcining at 600 °C for 4 h, have been investigated by means of XRD, TPR, XPS, DRIFTS, and Raman spectroscopy (RS). The formation of the compounds La2CrO6, La(OH)CrO4 and LaCrO4 under these conditions was evidenced. Strong peaks at 864, 884, 913, and 921 cm−1, as well as weak peaks at 136, 180, 354, 370, and 388 cm−1 in the RS spectrum of CrOx/La2O3 have been assigned to La2CrO6. 相似文献