Search results for "thiophene"
showing 10 items of 284 documents
Crystal structure and reactivity of 2-chloro-3,5-dinitrothiophene and of 2-phenylsulphonyl-3,5-dinitrothiophene with nucleophiles
1988
The geometry obtained by a crystal structure determination of the title compounds, as compared with that of the analogous benzene derivatives, along with results of ab initio calculations, is used to interpret the different SNAr reactivities in some thiophene and benzene compounds. The smaller rotation of the nitro groups with respect to the aromatic rings observed in thiophene derivatives should be considered a relevant factor in the higher reactivity in the thiophene series.
Electronic Spectra of 2,2‘-Bithiophene and 2,2‘:5‘,2‘ ‘-Terthiophene Radical Cations: A Theoretical Analysis
2001
Analysis of the electronic spectra of 2,2‘-bithiophene and 2,2‘:5‘,2‘ ‘-terthiophene radical cations has been performed by using multiconfigurational second-order perturbation theory (CASPT2). Atomic natural orbital (ANO) type basis sets of split valence quality, including polarization functions on all heavy atoms, have been used. In agreement with experimental data, in the energy range below the lowest optically allowed transition of the respective neutral system, theoretical results predict two main absorption bands for both cations. The 22Au and 32Au states computed at 1.94 and 2.80 eV, respectively, are related to the corresponding band maxima recorded for bithiophene cation. The 12B1 s…
Influence of the preparation method on the thiophene HDS activity of silica supported CoMo catalysts
2002
Abstract The effect of the preparation method of CoMo/SiO2 catalysts with and without sodium ions, on the hydrodesulfurization (HDS) of thiophene was investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 physisorption (BET). The samples were prepared by total sol–gel route, by classic wetness impregnation and by co-impregnation, in the presence of nitrilotriacetic acid (NTA), of commercial and sol–gel prepared silica. The influence of sodium ions added to the sol mixture and to the silica before the impregnation with Co and Mo salt solution, was also considered. The presence of sodium favoured the phase transition of amorphous silica to cristobalite with con…
ChemInform Abstract: A Versatile Palladium/Triphosphane System for Direct Arylation of Heteroarenes with Chloroarenes at Low Catalyst Loading.
2010
The present new catalyst system can be used for the direct arylation of various heteroaromatic compounds at low palladium loadings.
ChemInform Abstract: Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aq…
2011
Polyethylene glycol-tagged macrocycle (I) is prepared by a three-fold copper-catalyzed [3 + 2] cycloaddition reaction.
From One-Pot NH-Sulfoximidations of Thiophene Derivatives to Dithienylethene-Type Photoswitches
2019
Thiophene NH-sulfoximines have been synthesized using a one-pot NH-sulfoximidation reaction of thiophenes. The reactivity of the products was investigated, and the developed protocols were used for the synthesis of a new class of dithienylethene-type photoswitches containing a sulfoximidoyl group.
Versatile oxidative approach to carbazoles and related compounds using MoCl5.
2013
The unique oxidizing power of molybdenum pentachloride provides an easy to perform, versatile, and high yielding method to construct carbazoles and the corresponding dibenzo analogues of thiophene, furan, and selenophene. The coupling reaction tolerates a variety of functional groups. The synthesis is highly modular. By this approach a precursor for the naturally occurring carbazole koenigicine was prepared.
Crystal structure of (2E)-3-[4-(dimethylamino)phenyl]-1-(thiophen-2-yl)prop-2-en-1-one
2017
In the title chalcone-thiophene derivative, the dihedral angle between the aromatic and the thiophene rings is 11.4 (2)°. In the crystal, molecules are linked by C—H⋯O and C—H⋯S weak interactions along [100], forming rings of R22(8) graph-set motif, by C—H⋯O weak interactions along [010], forming C(6) chains, and by weak H(methyl–group)⋯Cg(thiophene ring) interactions into dimers; the crystal packing resembles a herringbone arrangement when viewed along [100]. A molecular docking calculation of the title compound with the neuraminidase enzyme was carried out.
Crystal structure and Hirshfeld surface analysis of 1-(2,4-dichlorobenzyl)-5-methyl-N-(thiophene-2-sulfonyl)-1H-pyrazole-3-carboxamide
2018
In the title compound, C16H13Cl2N3O3S2, the thiophene ring is disordered in a 0.762 (3):0.238 (3) ratio by an approximate 180° rotation of the ring around the S—C bond linking the ring to the sulfonyl unit. The dichlorobenzene group is also disordered over two sets of sites with the same occupancy ratio. The molecular conformation is stabilized by intramolecular C—H...Cl and C—H...N hydrogen bonds, forming rings with graph-set notation S(5). In the crystal, pairs of molecules are linked by N—H...O and C—H...O hydrogen bonds, forming inversion dimers with graph-set notation R 2 2(8) and R 1 2(11), which are connected by C—H...O hydrogen-bonding interactions into ribbons parallel to (100). Th…
Crystal structure of two N′-(1-phenylbenzylidene)-2-(thiophen-3-yl)acetohydrazides
2019
Two N′-(1-(phenylethylidene)-2-(thiophen-3-yl)acetohydrazides containing –OH and –OCH3 at the para-position of the phenyl ring have been synthesized and their molecular and crystal structures are reported.