نتایج جستجو برای: aromaticity and rahb
تعداد نتایج: 16827345 فیلتر نتایج به سال:
We herein describe a palladium-catalyzed formal aromaticity transfer coupling reaction between phenols and pyrrolidines or indolines to generate the corresponding N-cyclohexyl pyrroles or indoles. In this transformation, the aromaticity of phenols is formally passed on to the pyrrolidine or indoline units. Substituted phenols thus can serve as latent cyclohexyl equivalents for the fast construc...
Substitution of two or four carbon atoms by nitrogen in the corannulene molecule as a carbon nanostructure was done and the obtained structures were optimized at MP2/6-31G(d) level of theory. Calculations of the nucleus-independent chemical shift (NICS) were performed to analyze the aromaticity of the corannulene rings and its derivatives upon doping with N at B3LYP/6-31G(d) level of theory. Re...
Aromaticity can be interpreted as extra stabilization of a cyclic unsaturated molecule arising from cyclic conjugation of mr-electrons. The extra stabilization energy is estimated relative to the r-electron energy of a hypothetical reference molecule formed by the "localized" ir bonds. It is termed the resonance energy due to aromaticity. Our graph theory of aromaticity defines this type of res...
π-Aromaticity is an important driving force in directing the synthesis of aromatic compounds; contrast, reactions induced by σ-aromaticity are uncommon. Here we report a strategy based on π- and relays to realize structurally defined ring contraction metallacyclobutadiene metallacyclopropene. This reaction involves release π-antiaromaticity afford π-aromatic intermediate, followed reclosure gen...
In the 1- (4-fluorophenyl) -2,3-dihydro-1 H-naphto- [1 and 2-e] [1 and 3] oxazine-3-n, there are 4 rings, respectively, rings from the side attached to the halogen They are named C, B, A, and D. Calculations and studies show that the amount of aromatics in the halogen-ring A in all cases has the highest number. In the B loop, the predicted aromatism level is zero, and in the ring C and D, relat...
The most refined nucleus-independent chemical shift index (NICS(0)(πzz)) and the extra cyclic resonance energies (ECREs), based on the block localized wave function (BLW) method, show that the aromaticity of all azines is like that of benzene. The same is true for aza-naphthalenes relative to naphthalene. The lower relative energies of isomers with vicinal N's are due to the weakness of NN bond...
We have studied a series of bridged phenylacetylene macrocycles with topologies based on Platonic and Archimedean polyhedra, using density functional calculations to determine both their molecular structure and their electronic response to external magnetic fields (NICS maps). We are able to elucidate the interplay of aromaticity and anti-aromaticity as a function of structural parameters, in p...
The relationship between physicochemical properties of biochar-based activated carbons and its adsorption was investigated using an aromatic model compound, phenanthrene. Solid-state (13)C NMR analysis indicated more condensed aromatic structures when pyrolysis temperature increased or after activation process induced. The increasing aromaticity and non-protonated carbon fraction of the activat...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید