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931.
V. L Gein E. N. Bezmaternykh L. F. Gein I. V. Krylova 《Chemistry of Heterocyclic Compounds》2004,40(10):1332-1334
It has been shown that 5-aryl-3-arylamino-4-benzoyl-1H-3-pyrrolin-2-ones cyclize in the presence of conc. H2SO4 to give pyrrolo[3,4-b]quinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1543–1545, October, 2004. 相似文献
932.
Lauro J.Q. Maia Valmor R. Mastelaro Antonio C. Hernandes 《Journal of solid state chemistry》2007,180(2):611-618
A new sol-gel route was applied to obtain Y0.9Er0.1Al3(BO3)4 crystalline powders and amorphous thin films by using Al(acac)3, B(OPri)3, Y(NO3)3·6H2O, and Er(NO3)3·5H2O as starting materials dissolved in propionic acid and ethyl alcohol mixtures. Our study shows that propionic acid acts as good chelant agent for yttrium and erbium ions while ethyl alcohol allows to dissolve Al(acac)3. This process makes the resulting sols very stable to obtain homogeneous gels and transparent amorphous thin films. In addition, the propionic acid prevents the sol precipitation, making easy porous- and crack-free thin film depositions. Chemical reactions involved in the complexation were discussed. As-prepared powders and films are amorphous and present a good thermal stability due to their high glass transition (746 °C) and crystallization temperatures (830 °C). This new sol-gel route showed to be adequate to obtain dense and crack-free thin films free of organic and hydroxyl groups that can be considered as promising materials to be used in integrated optical systems. 相似文献
933.
G. Haxhillazi 《Journal of solid state chemistry》2004,177(9):3045-3051
The compounds (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] have been prepared and investigated by X-ray powder methods as well as Raman- and IR-spectroscopy. In the case of Rb3[Ta(O2)4] the structure has been solved from single crystal data. It is shown that all these compounds are isotypic and crystallize in the K3[Cr(O2)4] type (SG , No. 121). The infrared- and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral [Ta(O2)4]3− ion. Symmetry coordinates for the [Ta(O2)4]3− ion are given from which the vibrational modes of the O-O stretching vibrations of the O22− groups, the Ta-O stretching vibrations and the Ta-O bending vibrations are deduced. 相似文献
934.
Deyu Wang 《Journal of solid state chemistry》2004,177(12):4582-4587
Li2CO3 and LiOH·H2O are widely used as Li-precursors to prepare LiFePO4 in solid-phase reactions. However, impurities are often found in the final product unless the sintering temperature is increased to 800 °C. Here, we report that lithium fluoride (LiF) can also be used as Li-precursor for solid-phase synthesis of LiFePO4 and very pure olivine phase was obtained even with sintering at a relatively low temperature (600 °C). Consequently, the product has smaller particle size (about 500 nm), which is beneficial for Li-extraction/insertion in view of kinetics. As for cathode material for Li-ion batteries, LiFePO4 obtained from LiF shows high Li-storage capacity of 151 mAh g−1 at small current density of 10 mA g−1 (1/15 C) and maintains capacity of 54.8 mAh g−1 at 1500 mA g−1 (10 C). The solid-state reaction mechanisms using LiF and Li2CO3 precursors are compared based on XRD and TG-DSC. 相似文献
935.
Vashchenko V. V. Kutulya L. A. Pivnenko M. N. Shkolnikova N. I. 《Russian Chemical Bulletin》2003,52(11):2406-2418
(1R,4R)-2-(4-Hydroxybenzylidene)- and (1R,4R)-2-(4"-hydroxybiphenyl-4-yl)methylene-p-menthan-3-ones were synthesized by condensation of (–)-menthone with O-tetrahydropyran-2-yl derivatives of 4-hydroxybenzaldehyde and 4"-hydroxy-4-formylbiphenyl, respectively, in a DMSO—base medium followed by the removal of the protective group. The reactions of these hydroxy derivatives with 4-alkylbenzoic, 4-alkyloxybenzoic, trans-4-alkylcyclohexane-4-carboxylic, and 4"-alkylbiphenyl-4-carboxylic acids afforded three series of new chiral esters. Compounds containing the arylidene moiety with three benzene rings were found to exhibit liquid-crystalline properties. The characteristic features of these compounds are discussed based on the results of studies by polarizing microscopy, differential scanning calorimetry, and small-angle X-ray scattering. It was found that the mesomorphic compounds under study can form a smectic A mesophase, twist grain boundary mesophases (TGBA), and blue phases in a wide temperature range. Upon dissolution of certain of chiral compounds in 4"-cyano-4-pentylbiphenyl, a rather high twisting power and the thermal stabilizing effect on mesophases were observed. 相似文献
936.
Structures with AIB2? and BaAl4?type Units. I The Compounds Sr4Pd5P5 and Sr2Pd3P3 Sr4Pd5P5 (Cmcm, a = 4.177(1) Å, b = 31.377(5) Å, c = 8.581(2) Å, Z = 4) und Sr2 Pd3P3(Pmmm, a = 4.199(1) Å, b = 4.212(1) Å, c = 34.227(4) Å, Z = 4) have been prepared by heating the elements. Both structures contain exclusively units characteristic for the AIB2? and BaAl4?type. The ratio between isolated P-atoms and P2?pairs is interpreted with an ionic splitting of the formulas. 相似文献
937.
The dipole moments of 2-alkylaminoand 2-alkylnitramino-3(or 5)-methyl-4-nitropyridines and their N-oxides have been measured, as well as calculated, using vectorial summation of the group moments and by ab initio method. The estimated interaction dipole moments, int, have been discussed in terms of the electronic and steric effects and intramolecular hydrogen bonding. Introduction of the NHCH3 group to position 2 in 4-nitropyridine strengthens the conjugation between the nitro group and ring nitrogen. The lack of such strengthening in 4-nitropyridine-N-oxides is explained as being due to formation of intramolecular hydrogen bond between the N-oxide group and the hydrogen of alkylamino group. Introduction of the nitramino group does not lead to marked modification of the charge distribution in a molecule. This fact may be explained by much weaker electron-donating ability of this group in comparison with the alkylamino group. 相似文献
938.
Gerald Giester 《Monatshefte für Chemie / Chemical Monthly》1989,120(8-9):661-666
Summary Single crystal X-ray data of the hydrothermally grown new phase Li2Cu3(SeO3)2(SeO4)2 were measured with a four-circle diffractometer up to sin /=0.81 Å–1 [I2/a,Z=4,V=1175.5 Å3,a=16.293(6),b=5.007(2),c=14.448(6) Å, = 94.21(1)°]. The structure was determined by direct and Fourier methods and refined toR=0.034,R
w
=0.027 for 2 086 independent reflections.Cu(1)[4+1]O5 forms a tetragonal pyramid, Cu(2)[4 + 2]O6 is a strongly elongated octahedron. The Li atom is surrounded by four O atoms forming a distorted tetrahedron. Se(IV)O3 and Se(VI)O4 groups are in accordance to literature, mean Se-O bond lengths are 1.714 and 1.644 Å.
Die Kristallstruktur von Li2Cu3(SeO3)2(SeO4)2
Zusammenfassung Einkristall-Röntgendaten der hydrothermal gezüchteten neuen Phase Li2Cu3(SeO3)2(SeO4)2 wurden mit einem Vierkreisdiffraktometer im Bereich bis zu sin /=0.81 Å–1 gemessen [I2/a,Z=4,V=1175.5 Å3,a=16.293(6),b=5.007(2),c=14.448(6) Å, =94.21(1)°]. Die Kristallstruktur wurde mittels direkter und Fourier-Methoden bestimmt und für 2 086 unabhängige Reflexe zuR=0.034,R w =0.027 verfeinert.Cu(1)[4+1]O5 bildet eine tetragonale Pyramide, Cu(2)[4+2]O6 ist ein stark verlängertes Oktaeder. Das Li-Atom ist von vier O-Atomen in Gestalt eines verzerrten Tetraeders umgeben. Die Se(IV)O3-und Se(VI)O4-Gruppen entsprechen der Literatur, die mittleren Se-O-Abstände betragen 1.714 und 1.644 Å.相似文献
939.
The reactions of cyclic aldo- and -methoxynitrones of the 2H-imidazole-1-oxide and 4H-imidazole 3-oxide series with isocyanates, phenyl isothiocyanate, N-phenylmaleimide, and dimethyl acetylenedicarboxylate were studied. The reactions give the corresponding 1,3-dipolar cycloaddition products. 2,2-Dimethyl-4-phenyl-2H-imidazole 1-oxide does not enter into a similar reaction with isocyanates or phenyl isothiocyanate. 相似文献
940.
The reaction of 3-allylthio-5-phenyl-4H-1,2,4-triazole with iodine to give a mixture of 5,6-dihydro-5-iodomethyl-3-phenyl[1,3]thiazolo[2,3-c][1,2,4]triazole, 6,7-dihydro-6-iodo-3-phenyl-5H-[1,2,4]triazolo[3,4-b][1,3]thiazine, 5,6-dihydro-6-iodomethyl-2-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazole, and 6,7-dihydro-6-iodo-2-phenyl-5H-[1,2,4]triazolo[5,1-b][1,3]thiazine has been studied. The structure of the products obtained was established using 1H NMR spectroscopy of their dehydriodination products. 相似文献