Quinone Carbonyl Research Articles

Research on heterocyclic quinones

7-Hydroxy-1-isoquinolones, 3-methyl-7-hydroxyisoquinoline, and 6-hydroxyisoquinoline were synthesized, and their reactions, as well as the reaction of 7-methoxyisoquinoline-5,8-quinone, with amines were studied. The problem of the transmission of the mesomeric and inductive effects of the quinone carbonyl groups through the heteroring and the increase in the electrophilicities of the quinones upon chelate formation are discussed.

Quinoid groups in humic acids

Quinoid groups of humic acids from various sources (soil, peat, brown and oxidized coals) can undergo reversible redox transformations, this being a fundamental property of this class of natural compounds. Kinetic oxidation curves for reduced humic acids indicate the presence of various types of quinoid groups. The specificity of a previously suggested technique for determining quinones in humic acids has been corroborated. Exhaustive carbonyl reduction by sodium borohydride combined with reductometric methods for determining quinones in alkaline media make possible a better estimation of the ketone content in humic acids. When humic acids are reduced in an acid solution of tin chloride, rigorous conditions (4 h, 120°C, strong acid media) lead to an irreversible conversion of part of the quinone carbonyls and, as a result, the reaction proceeds nonstoichiometrically.

Surface oxides of activated carbon: Internal reflectance spectroscopic examination of activated sugar carbons

The nature of the activated carbon surface with respect to surface functional groups has been examined using infrared internal reflectance spectroscopy (IRS). By employing this recently developed technique, the surface character of laboratory-activated sugar carbons has been examined as a function of activation temperature and atmosphere. The IRS spectra obtained for series of O 2 and CO 2 + O 2 activated carbons indicate the presence of dicarboxylic acids and quinone carbonyl groups. The adsorption isotherms of p-nitrophenol on these carbons has been studied and has been shown to conform with the previously suggested adsorption mechanism involving the formation of a donor-acceptor complex with surface carbonyl oxygen.

Polarography of Anthraquinone Derivatives in Dimethylformamide: Effect of Hydrogen Bonding

The polarographic reduction is reported of anthraquinone, some methoxyanthraquinones, hydroxyanthraquinones, and aminoanthraquinones in dimethylformamide. Two reduction steps, each corresponding to the addition of one electron, were obtained for all compounds with the exception of 2-hydroxyanthraquinone, which gave four distinct steps. The introduction of hydroxyl groupings peri to the quinone carbonyl groupings caused the half-wave potentials of both steps to shift to less negative values. The shifts of the first reduction steps have been interpreted in terms of stabilization of the radical-ions by intramolecular hydrogen bonding.

MYCOCHRYSONE: I. ISOLATION, PROPERTIES, AND PRELIMINARY CHARACTERIZATION

Mycochrysone, an orange-red crystalline pigment, has been isolated from in vitro cultures of an inoperculate discomycetous fungus. It possesses quinonoid properties and forms a monoquinoxaline derivative. At least two phenolic or enolic groups are present, one of which is in the peri position to a quinone carbonyl. Reduction of the pigment with a zinc dust –zinc chloride mixture gives perylene, together with some hydroperylenes. The pigment shows limited antibiotic activity.