- SYNTHESIS AND SOLVATOCHROMIC AND ACID-BASE REACTIONS OF A BETAINE AND SALTS OF 4-N-PYRIDINIUMCATECHOL
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Oxidation of catechol by phenyliodosyldiacetate in the presence of pyridine gives 4-N-pyridiniumcatechol salts whose structures are confirmed by an independent synthesis from 2,2-dimethyl-5-aminobenzodioxole.The spectroscopically determined ionization constants for the 4-N-pyridiniumcatechol cation depend on the nature of the buffer cation solution (sodium, ammonium, tetraethylammonium).The large solvatochromic shift in the long wavelength absorption band of the betaine of 4-N-pyridinium-catechol followed the empirical scale of solvent polarity ENT.Introduction of the N-pyridinium group in position 4 increases the acidity of the catechol by 2.7 pK units, which is an almost identical effect to the introduction of a 4-nitro group.However, the solvatochromism for the anion of 4-nitrocatechol is insignificant.The compounds were characterized by their 1H NMR and IR spectra.
- Neiland, O. Ya.,Kraupsha, I. L.,Gudele, I. Ya.
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p. 1428 - 1434
(2007/10/02)
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- An Improved Method for the Synthesis of 2,2-disubstituted and 2-Monosubstituted 1,3-Benzodioxoles
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The reactions of catechol with ketones and aldehydes have been studied and convenient procedures have been developed for the preparation of the title compounds in high yields.These products undergo virtually quantitative nitration at position 5, thus providing a source of derivatives substituted in the benzene ring.
- Cole, Edward R.,Crank, George,Minh, H. T. Hai
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p. 675 - 680
(2007/10/02)
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- Imidazo pyridine-2-ones and pharmaceutical compositions and methods of treatment utilizing same
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1,3-Dihydroimidazo[4,5-b]pyridin-2-ones and corresponding thiones have utility as analgesic, antipyretic and antiinflammatory agents. They are generally prepared by treatment of a 2,3-diaminopyridine with phosgene or thiosphosgene followed by further substitution if desired.
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- 3-Phenyl,3H 1,2,3 triazolo[4,5-b]pyridines
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3H-1,2,3-Triazolo[4,5-b]pyridines substituted in the 3-position have utility as analgesic, anti-inflammatory and anti-pyretic agents. They are prepared by diazotization of a 3-amino-2-(substitute) aminopyridine.
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