Spectral characteristics and electronic structure of synthetic derivatives of coumarin. P a r t V. A study of the electronic structure of warfarin
Journal Title: Фармацевтичний журнал - Year 2014, Vol 6, Issue 6
Abstract
The drug warfarin – indirect anticoagulants of the coumarin group, is a competitive antagonist of vitamin К. To develop the optimum conditions of chemical-toxicological analysis we discovered fragments of the molecule warfarin, causing the absorption band of the electronic spectrum of the test compound (chromophore) and partly its pharmacological action (pharmacophore). Spectra were studied in the purified water, 95% ethanol, 0.1 M hydrochloric acid solution, 0.1 M sulfuric acid solution, 0.1 M solution of sodium hydroxide, chloroform, acetonitrile, and cyclohexane. Experience will help develop the optimal conditions of chemical-toxicological analysis of warfarin and identification of the molecule causes the appearance of maxima (chromophore) and partly its pharmacological action (pharmacophore). In contrast of 4-oxycoumarin, in the spectrum of warfarin does not occur splitting λmaks of unsubstituted coumarin at 274 nm at two peaks, resulting in the spectral curve observed only two or three absorption bands. Exceptions are alkaline solutions of warfarin, where formed of salts - cinnamic acids. Considering the electronic structure of warfarin and polarity of solvents used we must be concluded that the first absorption band of the electronic spectra of the test substance caused π→π*-electron transitions. It characteristic of the phenolic radical of molecule. The vibrational structure confirms its compliance of the ¹La-band. The second band corresponds to an allowed transition π→π* electrons in the benzene ring, and it should be attributed to ¹Lb-band. Highs third band emerged from the p–π-conjugation of the benzene ring of warfarin molecule with the group of the parent chromophore of enone (this coincides with the conjugation chain pharmacophore or a part of it). According to quantum-chemical calculations of the electron density on the Hückel method using the program Chemoffice 11 (MM optimization 2) found that reaction SE will primarily flow through C10 and then later on C8 benzene ring. At undergo nucleophilic attack lactone ring, whereby the disclosed cycle. The lactone ring may react AE, AN.
Authors and Affiliations
O. V. Grechana
Keywords
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