نتایج جستجو برای: substituent effects
تعداد نتایج: 1548409 فیلتر نتایج به سال:
"Substituent effects" is an important and useful concept in organic chemistry. Although there are many approaches to parametrizing the electronic and steric effects of substituents, the physical basis for the parameters is often unclear. The purpose of the present work is to explore the properties of chemical shifts in carbon 1s energies as a well-defined basis for characterizing substituents t...
Synthetic supramolecular zipper complexes have been used to quantify substituent effects on the free energies of aromatic stacking interactions. The conformational properties of the complexes have been characterised using NMR spectroscopy in CDCl(3), and by comparison with the solid state structures of model compounds. The structural similarity of the complexes makes it possible to apply the do...
where R = H and/or alkyl (aryl). Presence of electron-releasing substituents on alkene double bond increases the rate of oxythallation it is in accordance with Ads character of this reaction [2-5]. In earlier papers of this series we showed that oxidation of alkenes by an aqueous solution of thallic salts suits Taft's equation, and isokinetic relationship, too [6-8]. We studied the enthalpy ent...
Students in organic chemistry are taught a number of fundamental principles concerning the factors which govern the properties of organic compounds. Among these principles is the effect of substituents on the properties of aromatic rings, especially the benzene ring. For instance, we teach the students that the reactivity of the benzene molecule towards electrophilic substitution reactions is e...
In this study, absorption spectra of sixteen azo dyes have been recorded in various solvents. These azo dyes have substituents such as OH, SO3H, Cl, I, NO2, C2H5 and OCH3 in different positions of phenyl ring. There is a shift in λmax whose amount is dependent upon the type and position of substituent on the ring. The effects of substituent on the absorption spectra of azo dyes are interpreted ...
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