Most of the compounds have physiologically active properties, and their biological properties are often attributed to the heteroatoms contained in their molecules, and most of these heteroatoms also appear in cyclic structures. A Journal, Gazzetta Chimica Italiana called The action of hydroxylamine on γ-pyrone, Author is Parisi, Federico; Bovina, Pietro; Quilico, Adolfo, which mentions a compound: 27828-71-3, SMILESS is O=C(O)C1=CN=CC(O)=C1, Molecular C6H5NO3, Recommanded Product: 5-Hydroxynicotinic acid.
Treatment of γ-pyrone (I) with HONH2 gave a substance, C5H6N2O2 (II), to which was ascribed the structure 4-hydroxylaminopyridine 1-oxide. I (17.5 g.) in 20 ml. H2O and 13.5 g. HONH2.HCl in 50 ml. H2O containing 13.5 g. NaHCO3 kept in the dark 2-3 days at 20°, the crystalline product washed with H2O and desiccated in vacuo over CaCl2 yielded 76% II, m. 220°. II was unstable in aqueous alkali with formation of an intensely red solution Finely ground II (0.5 g.) in 40 ml. H2O hydrogenated with 0.2 g. PtO2, the mixture treated with 8 ml. N HCl and the filtered solution saturated with KOH, extracted with Et2O and the product recrystallized from C6H6 gave 4-H2NC5H4N, m. 160-1°, also prepared by reduction of 4-O2NC5H4NO. II (0.25 g.) in 20 ml. 20% H2SO4 stirred with instantaneous addition of 0.125 g. KMnO4 in 15 ml. H2O, extracted with CHCl3 and the residue on evaporation taken up in 8 ml. hot PhMe, the cooled tepid solution filtered, diluted with an equal volume of petr. ether and refrigerated gave green needles of 4-ONC5H4N(O) (III), m. 138-9°. II (1.0 g.) in 50 ml. H2O boiled 3-4 min. with addition of decolorizing C, the filtered solution kept 12 hrs. at 20° and the orange-yellow product repeatedly crystallized from alc. and H2O gave 0.15-0.20 g. 4,4′-azoxypyridine 1,1′-dioxide (IV), m. 236-7°. The mother liquors evaporated and the residue recrystallized from alc. yielded 4,4′-azopyridine 1,1′-dioxide (V), m. 246-7°. II (0.10 g.) in 10 ml. cold 20% H2SO4 treated with 0.10 g. III in 10 ml. H2O, the mixture kept 16 hrs. at 20° and adjusted to pH 6.5-7.0 with 20% NaOH and NaOAc gave IV, also produced by oxidation of II in AcOH with 30% H2O2. AcOH (15 ml.) containing 1 g. 4-O2NC5H4NO treated portionwise with 0.75 powd. Zn with external cooling the mixture kept 2 days and the filtered solution adjusted to pH 6.5-7.0, repeatedly extracted with CHCl3 gave 60 mg. IV, m. 235-6° (H2O-alc.). II (1.0 g.) triturated with 3-4 ml. aqueous 10% KOH with characteristic crepitation and the bright red product crystallized from 20 ml. hot H2O gave V, m. 246-7° (H2O). IV (0.5 g.) in 40 ml. H2O hydrogenated with 0.2 g. PtO2 with addition of 12 ml. 0.5N HCl, the filtered solution partially neutralized with 10 ml. 0.5N NaOH and the washed precipitate dried in vacuo gave the unstable 4,4-hydrazo pyridine (VI), m. above 270°, rapidly turning rose-violet, also produced by hydrogenation of V. The above filtered solution evaporated in vacuo and the residue recrystallized from alc. gave 90% VI.2HCl, m. 190°, also prepared more conveniently by passage of dry HCl through alc. VI. VI.2HCl in H2O treated with 10% excess 0.5N NaOH and boiled with atm. oxidation to complete soluble, the solution cooled and filtered from the main product, the mother liquor extracted with Et2O and the combined crops crystallized from H2O gave trans-4,4′-azo pyridine (VII), m. 108-9°. VII in absolute alc. saturated with dry HCl gave the di-HCl salt. VII (0.5 g.) in 20 ml. AcOH refluxed 12 hrs. with 20 ml. 36% H2O2, the mixture concentrated in vacuo, diluted with H2O and extracted with CHCl3, the dried extract evaporated in vacuo and the concentrate evaporated spontaneously, the residue taken up in H2O and adjusted to pH 7.0 with aqueous Na2CO3, extracted with CHCl3 and the product recrystallized from alc. or H2O gave IV. The mechanism of the formation of IV, a prime example of the reaction of the CO group of a pyrone with HONH2, was discussed.
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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method