Reactions of 1,4-naphthoquinone and 5-hydroxy-1,4-naphthoquinone with ninhydrin

Russian Chemical Bulletin - 1,4-Naphthoquinone and 5-hydroxy-1,4-naphthoquinone react with ninhydrin to give 2-(2-hydroxy-1,3-dioxo-2,3-dihydro-1H-inden-2-yl)naphthalene-1,4-dione and 8-hydroxy-...     

Studies on the interaction of Eu(III) with lawsone (2-hydroxy-1,4-naphthoquinone), lapachol (2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone), juglone (5-hydroxy-1,4-naphthoquinone) and plumbagin (2-methyl-5-hydroxy-1,4-naphthoquinone)

pH-metric studies show that one mole of Eu(III) interacts with three molecules of each of juglone, plumbagin, lawsone and lapachol in solution. The stability and thermodynamics of these systems (50% aqueous acetone, 0.1 M KNO₃ ionic strength) are discussed and explained.     

Amination of 5-hydroxy-1,4-naphthoquinone in the presence of copper acetate

The reaction of 5-hydroxy-1,4-naphthoquinone with butylamine in the presence of copper(II) acetate monohydrate on heating resulted in the formation of a mixture of regioisomeric 2,6- and 2,8-bis(butylamino)-5-hydroxy-1,4-naphthoquinones.     

Hydrogen bonding motif in 2-hydroxy-1,4-naphthoquinone

Self-assemblies of 2-hydroxy-1,4-naphthoquinone (HNQ) have been investigated using the (HNQ)_n (n=1–4) series as modeled systems employing ab initio Hartree–Fock calculations. The energetics and charge distribution in these molecular systems are presented. As revealed from the electron density in the highest occupied molecular orbital of the lowest energy conformers of (HNQ)_n (n=1–4) the charge percolates to the end unit of the assembly. This has been supported by the molecular electrostatic potential topography.     

Use of Ozone in Synthesis of 5-Hydroxy-1,4-naphthoquinone

The feasibility of low-waste production of 5-hydroxy-1,4-naphthoquinone with regeneration of Cr(VI) with the use of ozone was examined. The optimal conditions were found for oxidation of Cr(III) to Cr(VI) in the presence of manganese(II) sulfate.     

N－芳基－2－乙基－3－羟基－4－吡啶酮的微波合成

用微波辐射从2－乙基－3－羟基－4－吡喃酮和芳胺合成了系列N－芳基－2－ 乙基－3－羟基－4－吡啶酮，并对产物进行了紫外、红外、氢核磁和质谱表征。     

Synthesis of Tacrine Analogs Derived from N-Aryl-5-amino-4-cyanopyrazoles

Synthesis of 11 tacrine analogs derived from N-aryl-5-amino-4-cyanopyrazoles, by a Friedländer type reaction, is described. Their structures were confirmed by ¹H and ¹³C NMR spectroscopy, elemental analysis, and/or mass spectrometry.     

Tautomerism of 5-hydroxy-1,4-naphthoquinone-4-imines

The existence of tautomeric equilibrium in solutions of 5-hydroxy-1,4-naphthoquinone-4-imines between the p-quinoid and ana-quinoid forms was proven by electronic, PMR and NMR (¹⁴N) spectroscopy. It was found that replacement of the aryl group at the nitrogen atom of the imino group by an alkyl group, and also proton-donor solvents forming hydrogen bonds with the oxygen attached at the C₅ atom cause a shift of the tautomeric equilibrium in the direction of the ana-quinoid form.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2572–2576, November, 1989.     

Synthesis and structure of N-(4-dialkylaminophenyl)hexafluoro-1,4-naphthoquinone 4-imines

The reaction of heptafluoro-1-naphthol with N,N-dialkyl-p-nitrosoanilines or N,N-dialkyl-p-phenylenediamines in the presence of HIO₃ gave the corresponding polyfluorinated N-aryl-1,4-naphthoquinone 4-imine derivatives which exist in solution as equilibrium mixtures of Z and E isomers. 2,3,5,6,7,8-Hexafluoro-N-(4-dimethylaminophenyl)-1,4-naphthoquinone 4-imine in crystal has exclusively the Z-isomer structure.     

2,3-二取代-1,4-萘醌的合成

常温下, 在丙酮与水的混合介质中(V∶V＝1∶1), 4-羟基香豆素类化合物与1,4-萘醌进行Michael加成反应, 生成6个未见文献报道的2,3-二取代-1,4-萘醌. 产物经MS, 1H NMR, 元素分析表征, 确定了其化学结构.     

Reactions of N-Arylsulfonyl-2-arenesulfonamido-1,4-benzo-quinone 4-Imines with Naphthols

Reactions of N-arylsulfonyl-2-arenesulfonamido-1'4-benzoquinone 4-imines unsubstituted in thering or 6-chloro, 5'6-dichlorosubstituted with 1- or 2-naphthols, 2-methoxynaphthalene provided thecorresponding N-arylsulfonyl-2-arenesulfonamido-6-[2-hydroxy(methoxy)-1-naphthyl]-4-aminophenols fromthe unsubstituted reagent and reduction products from the mono- and dichlorosubstituted quinone imines.     

Synthesis of 2-aminopentafluoro-1,4-naphthoquinone derivatives

Potential biologically active derivatives of 2-aminopentafluoro-1,4-naphthoquinone modified at the amino group were synthesized in 32–96% yield by reactions of hexafluoro-1,4-naphthoquinone with nitrogen-centered nucleophiles.     

Thermal and spectral properties of alkali metal complexes of 2-hydroxy-1,4-naphthoquinone

Thermal and spectral studies of reactions between 2-hydroxy-1,4-naphthoquinone (lawsone) and sodium metal (Lw-1, Lw-1A, Lw-1B), CH₃COONa (Lw-2), NaOH (Lw-3), KOH (Lw-4), K₂CO₃ (Lw-5), Tris buffer (Lw-6), ammonia (Lw-7) are studied. Red solids of Lw-1 to Lw-7, Lw-1A, and Lw-1B were isolated and are characterized by elemental analysis, FT-IR, ¹H NMR and UV–Visible spectroscopy. FT-IR spectra of Lw-1A and Lw-1B show, ν _OH of adsorbed as well as coordinated water molecules between 3,600–3,100 cm^?1 and decrease in ν _C=O frequency of lawsone ligand. The benzenoid ring protons C(5)H, C(8)H, C(6)H and C(7)H in Lw-1A and Lw-1B show upfield shift in ¹H NMR spectra. Hypsochromic shift and bathochromic shift is observed to π–π* transition band (~329 nm) and charge transfer band (~455 nm), respectively in UV–Visible spectra of all compounds. Pyrolytic decomposition of all compounds is studied by nonisothermal TG studies in air. Step I in all compounds leads to loss of adsorbed water molecules. Decomposition of lawsone anion in all compounds occurs in two or more steps. Thermodynamically Lw-1 to Lw-7, Lw-1A and Lw-1B are different compounds and their decomposition mechanisms are varied. The respective metal oxide residue viz. (Na₂O or K₂O) obtained after complete decomposition of Lw-1 to Lw-5, Lw-1A, and Lw-1B, is analyzed by powder X-ray diffraction. The adsorbed as well as coordinated water molecules are revealed by DTA and DSC studies as endothermic peak at ~100 °C. Decomposition mechanisms for lawsone anion are proposed based on LC–MS, GC–MS, and TG studies. Thermal and spectral studies reveal the coordination of lawsone ligand in its naphthosemiquinone form with alkali metal ions.     

Synthesis and spectral properties of 1,4-naphthoquinone sulfanyl derivatives

Reactions of 2,3-dichloro-1,4-naphthoquinone with hexadecanethiol and other alkanethiols in ethanol in the presence of sodium carbonate afforded new symmetric and unsymmetrical sulfanylnaphthoquinone dyes.     

Hydroxylation of 4-arylimino-5-hydroxy-1,4-dihydronaphthalen-1-ones

Heating of 4-arylimino-5-hydroxy-1,4-dihydronaphthalen-1-ones with sodium hydroxide in the presence of K₃Fe(CN)₆ gives the corresponding 2,5-dihydroxy derivatives, while in the reaction with FeCl₃ 6H₂O 4-arylimino-3,5-dihydroxy-1,4-dihydronaphthalen-1-ones are formed.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004, pp. 1334–1336.Original Russian Text Copyright © 2004 by Bukhtoyarova, Ektova.