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101.
Sonication of aromatic aldehydes, urea and ethyl acetoacetate in presence of solvent (ethyl alcohol) or solvent-less dry media (bentonite clay) supported-zirconium (IV) chloride (ZrCl(4)) as catalyst at 35 kHz gives 6-methyl-4-substitutedphenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl esters proficiently in high yields. 相似文献
102.
Narsidas J. Parmar Bhagyashri D. Parmar Tushar R. Sutariya Rajni Kant Vivek K. Gupta 《Tetrahedron letters》2014
The thiopyrazole gave many new polycyclic thiopyranopyrazole-heterocycles when it was assembled with a variety of O-alkenylated/alkynylated salicylaldehydes and naphthaldehydes in Brønsted acidic ionic liquid, [Hmim]HSO4, via domino/Knoevenagel–hetero-Diels–Alder (DKHDA) reaction. The reaction is highly stereoselective and the work-up procedure required no chromatography of products in many cases. 相似文献
103.
Namita Soni J. P. Barthwal A. K. Saxena K. P. Bhargava S. S. Parmar 《Journal of heterocyclic chemistry》1982,19(1):29-32
Fifteen new 3-arylaminomethyl-5-(2-hydroxy-3,5-dibromophenyl)-1,3,4-oxadiazole-2-thiones were synthesized and characterized by their sharp melting points, elemental analyses and ir spectra. These substituted oxadiazolylthiones were evaluated for their enzyme inhibitory activity. All compounds inhibited in vitro monoamine oxidase and succinate dehydrogenase activity of rat brain homogenates. The degree of monoamine oxidase inhibition ranged from 59-93% at a final concentration of 1 × 10?4 M whereas the inhibition of succinate dehydrogenase was 49-100% at a final concentration of 5 × 10?5 M. 相似文献
104.
The characterization of the products of reactions between anhydrous/hydrated copper(II) acetate and the title acids having R = Me, C6H11, Ph and p-tolyl in different solvents and at different temperatures with the help of elemental analysis, TGA, DTA, room temperature magnetic susceptibility, IR, and UV-VIS and EPR spectral data reveal that a competition exists between the chelation of arsine to copper(II) on one side and the reduction of copper(II) to copper(I) and the subsequent chelation of the arsine to copper(I) and/or that of the arsine oxide to copper(II) on the other. This competition which is expected to be normally governed by the inductive effect of group R is disturbed by the change in reaction conditions leading to the conclusion that the reaction conditions rather than the inductive effect of the group R control the mode of reaction. 相似文献
105.
Swarn S. Parmar Mrs Harkeerat K. Bharaj Manohar L. Saighal 《Transition Metal Chemistry》1986,11(8):283-286
Summary A change of the reported medium of reaction oftrans- [CrCl2(OH2)4]Cl · 2H2O witho-R2AsC6H4CO2M (M = Na), from 95% ethanol to acetone, results in the change of an hydroxo — to an oxo — group (R = Ph), in the number of water molecules (R = Et or C6H11) and/or of ligand molecules (R =p-tolyl) in chromium(III)-arsine complexes. However, for R = Me, the same complex is obtained in each case. I.r. spectral data of these complexes favour the chelation of the carboxylate ion and non-coordination of arsenic(III) except for CrO(o-Ph2AsC6H4CO2) · 2.5 H2O in which arsenic(III) of the monotertiary arsine group appears to coordinate to chromium(III). This would seem to be the first example of this type. On the other hand, the reaction of CrO3 witho-R2As- C6H4CO2M (M = H) in 14.5 molar ratio in acetone yields only one type of complex,viz., [Cr3O3(o-R2As(O)C6H4-CO2)2(o-R2AsC6H4CO2)(H2O)6] · n H2O (n = 2, R = Me, C6H11 or Ph; n = O, R = Et). The arsine oxide molecules appear to chelate through As = 0 and the carboxylate oxygens while the arsine ligand binds only through the carboxylate oxygens leaving arsenic(III) uncoordinated as reported for the complexes obtained from the same reactants in 95% ethanol. 相似文献
106.
Large blue-green, transparent crystalline needles of [K-(2,2)diaza-[18]-crown-6]KGe(9).3en are prepared, in high yield, from the reaction of (2,2)diaza[18]-crown-6 in toluene with a solution of "KGe(4)" in ethylenediamine (en). The compound crystallizes in the orthorhombic space group Pnma (a = 10.9763(12) A, b = 27.265(3) A, c = 13.880(1) A; Z = 4). The crystal structure of [K-(2,2)diaza-[18]-crown-6]KGe(9).2en features one-dimensional [KGe(9)](-) bare intermetallic chains formed from the linking, via exo-bonds, of nido-Ge(9)(2-) clusters. Uncomplexed K atoms effectively cap the square bases of the monocapped square antiprismatic [Ge(9)](2-) clusters. The optical band gap of the title compound is 1.25 eV. The use of weaker sequestering agents in the isolation of Ge cluster anions from en solutions provides an additional handle in a controlled molecular route to preparing new low-dimensional Zintl phases. 相似文献
107.
Several 4-aryl-l-[3-(2-aryl)indolyl]-3-thiosemiearbazones and 3-aryl-4-oxothiazolin-2-yl-[3-(2-aryl)indolyl] hydrazones were synthesized as possible antilertility agents. J. Heterocyclic Chem., 15 , 677 (1978) 相似文献
108.
109.
110.
Parmar KP Méheust Y Schjelderupsen B Fossum JO 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):1814-1822
We have studied the effect of an external direct current (DC) electric field ( approximately 1 kV/mm) on the rheological properties of colloidal suspensions consisting of aggregates of laponite particles in a silicone oil. Microscopy observations show that, under application of an electric field greater than a triggering electric field Ec approximately 0.6 kV/mm, laponite aggregates assemble into chain- and/or columnlike structures in the oil. Without an applied electric field, the steady-state shear behavior of such suspensions is Newtonian-like. Under application of an electric field larger than Ec, it changes dramatically as a result of the changes in the microstructure: a significant yield stress is measured, and under continuous shear the fluid is shear-thinning. The rheological properties, in particular the dynamic and static shear stress, were studied as a function of particle volume fraction for various strengths (including null) of the applied electric field. The flow curves at constant shear rate can be scaled with respect to both the particle fraction and electric field strength onto a master curve. This scaling is consistent with simple scaling arguments. The shape of the master curve accounts for the system's complexity; it approaches a standard power-law model at high Mason numbers. Both dynamic and static yield stresses are observed to depend on the particle fraction Phi and electric field E as PhibetaEalpha, with alpha approximately 1.85 and beta approximately 1 and 1.70 for the dynamic and static yield stresses, respectively. The yield stress was also determined as the critical stress at which there occurs a bifurcation in the rheological behavior of suspensions that are submitted to a constant shear stress; a scaling law with alpha approximately 1.84 and beta approximately 1.70 was obtained. The effectiveness of the latter technique confirms that such electrorheological (ER) fluids can be studied in the framework of thixotropic fluids. The method is very reproducible; we suggest that it could be used routinely for studying ER fluids. The measured overall yield stress behavior of the suspensions may be explained in terms of standard conduction models for electrorheological systems. Interesting prospects include using such systems for guided self-assembly of clay nanoparticles. 相似文献