Alexander J. Fatiadi

Phenylhydrazono-phenylazo tautomerism : Part II. Structures of 2-oxo-1,3-bis(phenylhydrazono) compounds and related compounds

Abstract The structures of xylo -4,5,6,-trihydroxy-2-oxo-1,3-bis(phenylhydrazono)cyclohexane ( 1 ), 2-oxo-1,3-bis(phenylhydrazono)cyclohexane ( 2 ), 2-oxo-1,3-bis(phenylhydrazono)cyclopentane ( 3 ),3-oxo-2,4-bis(phenylhydrazono)cyclohexane-1-carboxylic acid ( 4 ), 2-oxo-1,3-bis(phenylhydrazono)indan ( 5 ), and 2-oxo-1,3-bis(phenylhydrazono)propane ( 6 ) were studied by comparison of their n.m.r., u.v., visible, and i.r. spectra with the spectra of reference compounds of known structures. The results showed that compounds 1 - 6 exist in two forms. The red forms have an enolic (chelated) phenylhydrazono-phenylazo structure. A similarity of the compounds to the diphenylformazans is noted, and substantiated by a comparison of absorption spectra. Compound 2 crystallizes from aqueous ethyl alcohol in the form of a yellow hydrate shown to have a phenylhydrazono structure. On dehydration, the yellow hydrate yields the red enolic form. The n.m.r. spectra of 1,2,3-tris(phenylhydrazono) derivatives of cyclohexane, cyclopentane, and cyclohexanecarboxylic acid show two low-field signals indicative of two chelated rings. Tris(phenylhydrazono)propane in chloroform- d shows no low-field n.m.r. signals immediately after dissolution, but, after equilibration, shows a weak, low-field signal; this suggests that the substance may establish an equilibrium analogous to the equilibria reported by others for phenylosazones.

Electrochemical oxidation of several oxocarbon salts in N,N-dimethylformamide

The oxocarbon salts of croconic acid and its dicyanomethylene derivatives have been shown to undergo two consecutive reversible one-electron transfers in N,N-dimethylformamide to produce stable radical anions and the neutral croconates. Disproportion equilibrium constants were found to be quite small for all the crononate radical anions investigated. Following chemical reactions accompanied the second oxidation process of dicyanomethylene-substituted crononates. Substituent effects were shown to be ring position-independent and are discussed with respect to the unique resonance structure of the crononates.

Phenylhydrazono-phenylazo tautomerism : Part I. xylo-4,5,6-trihydroxy 2-oxo-1,3-bis(phenylhydrazono)cyclohexane and 4-oxo-1-phenyl-5-phenylazo-3-pyridazine derivatives

Abstract The positions of the phenylhydrazono groups in xylo -4,5,6-trihydroxy-2-oxo-1,3-bis(phenylhydrazono)cyclohexane were established by degradation of the compound with sodium metaperiodate and identification of the reaction product. The dialdehyde initially formed by periodate oxidation (but not isolated) cyclized to 4-oxo-1-phenyl-5-phenylazo-3-pyridazinecarboxaldehyde, which gave a crystalline methyl hemiacetal, an oxime, a semicarbazone, and, by oxidation, the corresponding monocarboxylic acid and sodium salt. Upon treatment with phenylhydrazine at 50°, the carboxaldehyde gave a red, crystalline phenylhydrazone which, with phenylhydrazine at 130°, gave a product that appears to be 4-oxo-1-phenyl-5-phenylhydrazo-3-pyridazinecarboxaldehyde phenylhydrazone. The reactions provide a route to a series of pyridazine derivatives which may prove valuable for the synthesis of unusual compounds for biological and medical research. xylo -4,5,6-Trihydroxy-2-oxo-1,3-bis(phenylhydrazono)cyclohexane exists in a yellow keto form and in a red enolic form. On warming in toluene, the yellow form gives the red form, which has an enolic phenylhydrazono-phenylazo structure.

Separation of pyrenediones by column

Abstract The 1,6- and 1,8-pyrrenediones were separated directly on a column of silica gel by means of glacial acetic acid as the eluant. The final purification of 1,6-pyrenedione was accomplished on a column of activated alumina by use of benzene as the solvent. The infrared and ultraviolted speactra of purified 1,6-, 1,8-, and 4,5-pyrenediones and of 1-oxo-6,7-phenalenedicarboxylic acid anhydride were recorded.

The Oxidation of Organic Compounds by Active Manganese Dioxide

In the series of reagents used in heterogeneous oxidation reactions, active manganese dioxide has acquired a prominent place among such oxidants as copper oxide, mercury(II) oxide, silver oxide, lead dioxide, sodium bismuthate, 1–3 nickel peroxide, 4, 5 manganese(III) acetate, 6, 7 silver carbonate on Celite, 8 seloxcette9 (chromic anhydride intercalated in graphite), and the recently introduced potassium permanganate on molecular sieves10 and barium manganate (BaMnO4).11, 12 The last two reagents10, 11 may be efficient oxidants for the conversion of alcohols into carbonyl compounds (under mild conditions).

Bromine oxidation of inositols for preparation of inosose phenylhydrazones and phenylosazones

Abstract The application of bromine oxidation of inositols to give inososes, followed by conversion of the latter into phenylhydrazones or phenylosazones, is described. The diketone from myo -inositol gives a phenylosazone in 22–30% yield, and l -inositol gives a monoketone phenylhydrazone (12% yield) and a diketone phenylosazone (28% yield); the corresponding enantiomorphs were obtained in 8% and 29% yield, respectively. The diketone from quebrachitol yields a new phenylosazone (29% yield) and no monoketone was isolated. Pinitol gave a new diketone phenylosazone (10–15% yield) which showed rapid mutarotation in 1:1 (v/v) ethanol- p -dioxane. In addition, a new phenylosazone has been obtained from dl - epi -inosose-2 phenylhydrazone. (+)- proto -Quercitol (from acorns) has been converted into a phenylosazone (20% yield). myo -Inositol has been converted by bromine oxidation into dl - xylo -pentahydroxy-2-cyclohexen-1-one in low yield.

Hydrazine derivatives of carbohydrates and related compounds

Publisher Summary This chapter provides an overview of the hydrazine derivatives of carbohydrates and related compounds. Hydrazine, hydroxylamine, and hydrogen peroxide are highly reactive nucleophiles that add to carbonyl compounds to give N - and O -adducts, which are not usually isolated. The chapter presents an account of the rich chemistry of the hydrazine derivatives of sugars, the versatility of their structures, and their availability, which makes them valuable enantiomerically pure synthons for chiral products. For example, reduction of aldose hydrazones affords an important class of chiral amino- and iminodeoxy sugars that contain nitrogen in place of the oxygen present in the rings of natural sugars. These imino sugars exhibit a wide spectrum of biological activities, mainly attributable to their ability to act as enzyme inhibitors. Also of considerable interest are the carba-sugars—the carbocyclic analogs of monosaccharides—which are readily available from inosose phenylhydrazones. Members of both these classes of compounds—the carba-sugars and the imino sugars (“aza sugars”)—are capable of inhibiting enzymes because they mimic the enzymes natural substrates (the sugars). This chapter provides an overview of saccharide hydrazones and glycosylhydrazines and also discusses about saccharide osazones and poly(hydrazones).

Priority toxic pollutants in human urine: Their occurrence and analysis

Abstract This survey reviews and discusses the occurrence of priority pesticides and industrial chemicals in human urine. An overview of some recent analytical methodology for determination of selected toxic pollutants and their metabolites as they are found in human urine is also presented.

The mechanism of formation of tris(phenylhydrazones) on treatment of cyclohexane-1,3-diones with phenylhydrazine

Abstract Treatment of the enolic cyclohexane-1,3-diones in aqueous acetic acid with an excess of phenylhydrazine at room temperature gave mixtures of the corresponding 2-oxo-1,3-bis(phenylhydrazone) and tris(phenylhydrazone) derivatives in low to moderate yield. E.s.r. study of the reaction path indicated that free-radical anionic intermediates are partially involved. Treatment of an enolic cyclohexane-1,2-dione (or of α-hydroxy or α-acetoxycyclohexanones) with phenylhydrazine gave mixtures of the corresponding mono- and bis(phenylhydrazones); formation of radical-anions was also observed in these reactions.

Phenylhydrazono-phenylazo tautomerism. : Part III. Reactions of phenylformazans and certain bis(phenylhydrazones) with strong acids

Abstract The behavior of diphenylformazans, 2-oxo-1,3-bis(phenylhydrazones), 1,2-bis-(phenylazo)ethylene, and the phenylhydrazone of 4-oxo-1-phenyl-5-phenylazo-3-pyridazinecarboxaldehyde on protonation has been examined spectrophotometrically. These compounds form purple, blue, or green protonated cations. The nature of the spectral changes suggests that the highly colored cations have resonance-stabilized structures. Phenylosazones and bis(phenylhydrazono) compounds that cannot form resonance-stabilized cations on protonation do not usually give the blue-color reaction. Structures are proposed for the cations derived from diphenylformazans and certain 2-oxo-1,3-bis(phenylhydrazones). Treatment of the red, enolic tautomer of 2-oxo-1,3-bis(phenylhydrazono)-cyclohexane with perchloric acid in acetic acid yields a new, stable, dark-blue, crystalline salt. Dissolution of this salt-in acetic acid, followed by addition of ice-water, yields a previously described yellow hydrate of the keto tautomer. Dissolution of the hdyrate in ethanol and warming regenerates the red, enolic tautomer. E.s.r. measurements of colored solutions of 2-oxo-1,3-bis(phenylhydrazones) or diphenylformazans did not show the presence of radical species, thus indicating the ionic character of the products formed on protonation.