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Photochemistry Of Aromatic Compounds Pdf Download

Photobases are compounds which become strong basesafter electronic excitaton into a charge-transfer excited state. Recent experimental studies have highlightedthe photobasicity of the 5-R quinoline compounds, demonstrating a strongsubstituent dependence to the pKa*. Here we describe our systematicstudy of how the photobasicity of four families of nitrogen-containingheterocyclic aromatics are tuned through substituents. We show that substituent position andidentity both significantly impact the pKa*. We demonstrate that the substituent effectsare additive and identify many disubstituted compounds with substantiallygreater photobasicity than the most photobasic 5-R quinoline compound identifiedpreviously. We show that the addition ofa second fused benzene ring to quinoline, along with two electron-donatingsubstituents, lowers the vertical excitation energy into the visible while still maintaining a pKa* > 14. Overall, the structure-function relationshipsdeveloped in this study provide new insights to guide the development of newphotocatalysts that employ photobasicity.

photochemistry of aromatic compounds pdf download

For Balakhani oil to be used as petroleum luminophores, the various aromatic groups separated by column absorption chromatography were studied by UV and IR spectroscopies by exposure to photo-irradiation at different times. Based on the electron absorption spectra of the samples and the considerations of the photochemical transformation mechanisms of different aromatic groups, it was proposed that the photochemical transformation processes in the aromatics of the studied oil proceeded by radical-chain and molecular mechanisms. It has been found that linear aromatic compounds oxidized in an oxygen environment to form endoperoxides and these compounds form quinones and hydroquinones during subsequent photooxidation, while acenes form cyclic peroxides.

The photostabilizing effect of many aromatic compounds to be UV stabilizer for several polymers has been reported. This is due to their filtrating action which depends in turn, on their absorption characteristics (Ranby and Rabek 1975; Heller 1969).

The excited state of a chromophore (Ch) where Ch is a chromophore such as dyes, pigments, antioxidant products, carbonyl groups, a variety of impurities or pollutants such as polynuclear aromatic compounds may react but it can also be made to transfer its excess electronic energy to a quenching entity (Q) (see Figure 32).

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