نتایج جستجو برای: electron withdrawing
تعداد نتایج: 310077 فیلتر نتایج به سال:
The first Suzuki cross-coupling reaction of aryltrimethylammonium triflates based on the use of an IMes.Ni(0) catalyst system is described. A wide range of electron-withdrawing and electron-donating substituents are tolerated on both the aryltrimethylammonium triflate and the boronic acid components of this reaction. In addition to arylboronic acids, the scope of the reaction is extended to enc...
Thiosemicarbazones possessing electron-donating and electron-withdrawing groups were prepared, and their spectral characteristics determined. In all cases, the spectra showed that one isomer was formed, allowing further functionalization to molecules of biological interest. We provide NMR data for some of the thiosemicarbazones and semicarbazones. We also provide evidence that for 2-pyridyl thi...
The Cu(I)-catalyzed N,N'-diarylation of natural diamines and polyamines such as putrescine, cadaverine, spermine, spermidine and their homologues is described. Aryl iodides bearing electron-donating and electron-withdrawing groups have been employed in the study. The CuI/2-(isobutyryl)cyclohexanone/DMF catalytic system has found to be more efficient in the diarylation of diamines and spermine w...
The title compound, C(15)H(12)N(2)OS(2), is an example of a push-pull butadiene in which the electron-releasing methyl-sulfanyl groups and electron-withdrawing nitrile groups on either end of the butadiene chain enhance the conjugation in the system. Short intra-molecular C-H⋯S inter-actions are observed. In the crystal structure, an O⋯C short contact of 2.917 (3) Å is observed.
Three new D–A polymers PIDTT-DTBO, PIDTT-DTBT and PIDTT-DTFBT, using indacenodithieno[3,2-b] thiophene (IDTT) as the electron-rich unit and benzoxadiazole (BO), benzodiathiazole (BT) or difluorobenzothiadiazole (FBT) as the electron-deficient unit, were synthesized via a Pd-catalyzed Stille polymerization. The included electron-withdrawing atoms of the acceptor portion were varied between O, S,...
Current models describe aromatic rings as polar groups based on the fact that benzene and hexafluorobenzene are known to have large and permanent quadrupole moments. This report describes a quantitative study of the interactions between oxygen lone pair and aromatic rings. We found that even electron-rich aromatic rings and oxygen lone pairs exhibit attractive interactions. Free energies of int...
Several arylsulphonamides of the configuration, 4-X-C6H4SO2NH2 (where X1⁄4H; CH3; C2H5; F; Cl; Br; I or NO2) and i-X, j-YC6H3SO2NH2 (where i-X, j-Y1⁄4 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3,4-Cl; 2-CH3,5-Cl; 3-CH3,4-Cl; 2,4-Cl2 or 3,4-Cl2) were prepared, and their infrared spectra were measured in the solid state. The NMR spectra were recorded in solution. N H asymmetric and symmetric stretc...
Molecular copper water oxidation electrocatalysts have been extensively studied in recent years for their potential use artificial photosynthetic systems solar energy conversion. Although ligand modification and its ability to influence catalytic properties is a key advantage of molecular systems, there are, as yet, few examples systematic studies these effects. Our oxidatively resistant pyalk ...
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