نتایج جستجو برای: aromatic
تعداد نتایج: 42254 فیلتر نتایج به سال:
This study analyzes the aromatic nature of cyanuric acid (hexahydrotriazine) and some of its derivatives, in terms of aromatic stabilization energy (ASE) and electronic behavior. The simplest molecule (C(3)N(3)O(3)H(3)) is the most aromatic item out of the entire set, but some of the others also display aromatic character. The structure of all the rings is analyzed considering their molecular o...
In 1972 Erich Clar formulated his aromatic π-sextet rule that allows discussing qualitatively the aromatic character of benzenoid species. Now, 40 years later, Clar's aromatic π-sextet rule is still a source of inspiration for many chemists. This simple rule has been validated both experimentally and theoretically. In this review, we select some particular examples to highlight the achievement ...
The essential oil of the stems and fruits of Caralluma europaea (Guss.) N.E.Br. (Apocynaceae) from Lampedusa Island has been obtained by hydrodistillation and its composition analyzed. The analyses allowed the identification and quantification of 74 volatile compounds, of which 16 were aromatic and 58 non-aromatic. Stems and fruits contained 1.4% and 2.7% of aromatic compounds respectively, whi...
A new approach to stabilize compounds containing a planar tetracoordinate carbon (ptC), embedded in aromatic hydrocarbons, is presented herein. This is achieved by using ligands that promote the formation of a 3c-2e σ-bond with the ptC under two conditions: without altering the sp2 hybridization of the aromatic carbons; and containing empty orbitals perpendicular to the aromatic ring to partici...
Here the aromatic formylation mediated by TiCl4 and dichloromethyl methyl ether previously described by our group has been explored for a wide range of aromatic rings, including phenols, methoxy- and methylbenzenes, as an excellent way to produce aromatic aldehydes. Here we determine that the regioselectivity of this process is highly promoted by the coordination between the atoms present in th...
Atmospheric processing of aromatic compounds, which are known pollutants in urban air occurring predominantly from road transport sources, are a major contributor to photochemical oxidant formation as evidenced by the formation of ozone. It is believed that urban atmospheres contain a mixture of in excess of 100 speciated aromatic volatile organic compounds (VOC). Recent studies in understandin...
Twenty-eight new aromatic esters of camptothecins 2-29 were prepared in yields of 5 to 96% by straight acylation of camptothecin (1a) and 9-nitrocamptothecin (1b) with various aromatic acids as acylating agents. All of these esters were tested against 14 different human cancer cell lines. The antitumor activity of these compounds was related to the nature of the substituting groups of their sid...
Background and objectives: Herbal aromatic waters are one of the products used in the Iranian traditional medicine. These products have small amount of essential oil. The purpose of this study was to identify the effective substances of herbal aromatic waters by various techniques (GC/FID and GC/MS). It is hoped that with assessment of these compounds by mentioned techniques a ...
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