Solubilities of some recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives in supercritical carbon dioxide

The solubility of four recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives, as potential complexing agents in some extraction and membrane transport experiments, have been measured in supercritical carbon dioxide. The measurements were carried out in the pressure range 120-400 atm at temperatures 35, 45, 55, 65, and 75 degrees C. The measured solubilities were correlated using the model proposed by Chrastil. The calculated results show good agreement with the experimental data.     

Normal coordinate analysis of fused-ring p-quinones: In-plane vibrations of 1,4-naphthoquinone and 9,10-anthraquinone

A normal coordinate analysis of the in-plane vibrations of 1,4-benzoquinone, 1,4-naphthoquinone, 9,10-anthraquinone and their fully deuterated analogues has been performed by using the overlay technique. The 38 parameters Modified Internal Valence Force Field has been successfully derived by combining those available for catacondensed aromatic hydrocarbons and for chlorinated p-benzoquinones. The results of the calculations clear up most of the remaining uncertainties in the vibrational assignments of 1,4-naphthoquinone and 9,10-anthraquinone. The reported force field provides a useful framework on which to base the vibrational analyses of the family of fused-ring p-quinones.     

Tautomerism of anthraquinones: V. 1,5-Dihydroxy-9,10-anthraquinone and its substituted derivatives

1,5-Dihydroxyanthraquinone and its substituted derivatives are capable of existence in the states structurally described as 9,10-, 1,10-, and 1,5-quinoid tautomerism, and as rotational isomerism involving a cleavage of intramolecular hydrogen bond. 1,5-Quinoid tautomers are characteristic only of substituted derivatives, and also appear in some metal complexes. The considerable color changes on introducing into the 1,5-dihydroxy-anthraquinone methyl, methoxy, and sulfo groups are caused by the shift in tautomeric and conformer equilibria.     

Tautomerism of anthraquinones: IV. 1-Hydroxy-9,10-anthraquinone and its substituted derivatives

1-Hydroxyanthraquinone and its substituted derivatives exist as equilibrium mixtures of four tautomers and rotational isomers. Their anions have 9,10-and 1,10-quinoid structures. Each tautomer or conformer is characterized by a single π₁,π* band in the electronic absorption spectrum.     

Electrochemical behaviour of some naturally occurring hydroxy derivatives of 9,10-anthraquinone in chloroform at mercury and glassy carbon electrodes: application of AC polarography to the analysis of rhubarb roots

Electrochemical behaviour of some naturally occurring hydroxy derivatives of 9,10-anthraquinone such as chrysophanic acid (Ch), rhein (Rh) and emodin (Em) at mercury and glassy carbon electrodes using two different supporting electrolytes in chloroform is described. In the presence of piperidinium perchlorate (0.75M) + piperidine (0.25M) as a suitable acid supporting electrolyte, the reduction of Ch and Rh was a reversible two-electron process without complicating chemical reactions or adsorption phenomena, but the reduction process of these compounds in the presence of tetrabutylammonium perchlorate (TBAP) 0.5M + 5% acetic acid (AcOH) in chloroform was quasi-reversible. In both supporting electrolytes the overall reduction process of Em was irreversible. In the AC polarography and DP voltammetry at a GC electrode, the detection limit for Ch, Rh and Em was acceptably low and the relative standard deviation for the determination of 5 x 10(-6)M level, never exceeded 2%. AC polarography has been used for the determination of Ch and Em in a local rhubarb sample after extraction into chloroform and separation by column chromatography.     

Quantum-chemical and correlation study on the tautomerism and ionization of 1,4,5,8-tetrahydroxy-9,10-anthraquinone and its alkyl-substituted derivatives

1,4,5,8-Tetrahydroxy-9,10-anthraquinone and its alkyl derivatives exist as equilibrium mixtures of prototropic tautomers and rotational isomers differing in the mode of intramolecular hydrogen bonding. Their electronic absorption spectra contain π_l,π* bands corresponding to 9,10-, 1,10-, 1,4-, and (more rarely) 1,5-anthraquinoid structures. Introduction of substituents, solvation, ionization, and complex formation lead to displacement of tautomeric and conformational equilibria, which are responsible for the observed diversity of their absorption spectra.     

Synthesis of 5-Aryl-1,4-naphthoquinone and 1-Aryl-9,10-anthraquinone Derivatives by Cycloaddition of 1-(Dimethoxyphenyl)-3-trimethylsiloxy-1,3-butadienes to 1,4-Benzoquinones and 1,4-Naphthoquinones

The Diels-Alder reaction of new 1-(3,4-dimethoxyphenyl)- or 1-(2,4-dimethoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2,5- and 2,6-dibromo-, and 2-bromo-6-methyl-1,4-benzoquinones regioselectively yields substituted 7-hydroxy-5-(dimethoxyphenyl)-1,4-naphthoquinones. By cycloaddition of the siloxydienes to naphthoquinone, bromonaphthoquinone, and juglone the corresponding substituted 3-hydroxy-1-(dimethoxyphenyl)-9,10-anthraquinones or their 4,4a-dihydro or 1,1a,4,4a-tetrahydro derivatives were obtained.     

Polarographic behaviour of uranium beta-diketonates in chloroform Application of ac polarography to the analysis of uranium minerals

The polarographic behaviour of U(VI) β-diketonates has been studied in chloroform. The conditions for reversible electrochemical reduction of U(VI) acetylacetonate and benzoylacetonate at a dropping mercury electrode was optimized by using a suitable ratio of piperidinium perchlorate and piperidine mixture as supporting electrolyte in chloroform. The one-electron nature of the reduction wave of U(VI) complexes was confirmed by controlled potential coulometry. The ac method preceded by a solvent extraction of U(VI) benzoylacetonate in chloroform was used for the determination of uranium. The calibration curve was linear over the range 0.5–20 μ/ml. The correlation coefficient was 0.9998 and the detection limit was about 0.2 μ/ml. The interference of some concomitant ions were examined and EDTA was used as an effective masking agent to separate uranium from other metals. The proposed method has been applied to the determination of uranium in uranium minerals.     

Laser flash photolysis and magnetic field effect studies on the interaction of uracil and its derivatives with menadione and 9,10-anthraquinone

Laser flash photolysis and an external magnetic field have been used to study the interaction of two quinone molecules, namely, 9,10-anthraquinone (AQ) and 2-methyl-1,4-naphthoquinone, commonly known as menadione (MQ), with the RNA base uracil (U) and two of its derivatives, 1,3-dimethyluracil (dmU) and uridine (dU). We have conducted our studies in homogeneous organic and heterogeneous micellar media in order to investigate the effect of media on the molecules and any change in reactivity on account of substitution. In organic homogeneous medium, both the quinones have behaved similarly with the bases. Here U has undergone both electron transfer (ET) and hydrogen (H) transfer, while dU and dmU have failed to exhibit any ET. Failure to support ET has been attributed to keto-enol tautomerism, which has been found to have a significant role in determining the occurrence of ET from these pyrimidine bases. However, in SDS micelles some variations regarding the reactivity of these molecules have been discerned. The variations are 2-fold. Here ET from U has been found to get completely eclipsed by a dominant H abstraction with both the quinones, and AQ reveals a difference in the extent of H abstraction with the bases in SDS. With U and dU, the prevailing H abstraction with AQ has succeeded in formation of only AQH(*), while dmU has produced both AQH(*) and AQH(2), the latter being formed by two successive H abstraction. Explanations of this intriguing behavior with U and its derivatives with quinone molecules have been the main concern in this work.     

Synthesis and Antitumor Activity of 2-[1-(2-Formylamido-3-phenylpropionyloxy)alkyl]-1,4dihydroxy-9,10-anthraquinone Derivatives

A series of 2-[1-(2-formylamido-3-phenylpropionyloxy)alkyl]-1,4-dihydroxy-9,10-anthraquinone(2FPADHAQ) derivatives was designed and synthesized.Their antitumor activities were tested against L1210 tumor cells and P388 mouse leukemic tumor cells in vitro and in ICR mice bearing sarcoma 180 cells in vivo.Overall,the introduction of 2-formylamido-3-phenyl-propanoic acid(2-FPPA) into the C-2-alkyl side chain C’-1 hydroxy group in 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinones(2-HDHAQ) enhanced the antitumor activity compared with the starting materials.2-FPADHAQ with alkyl chains longer than the pentyl group had negligible activity,whereas compounds 2b,2c,2d and 2e possessing shorter chains demonstrated moderate cytotoxic activity[50% effective dose(ED 50) of L1210 and P388 are 2.61―4.75 and 5.84―8.74 μg/mL],whereas compound 2l with an aromatic system showed strong cytotoxic activity.T/C(%) values[(average survival days in the test group)/(average survival days in the control group)×100%] also show that the introduction of 2-FPPA into the side chain of 2-HDHAQ enhanced antitumor activity.These data suggest that the introduction of an amino acid into the starting material may increase its affinity for DNA or its selectivity for proliferating cancer cells.     

Additivity of theHammett reaction constants ion pairs effect in the polarographic reduction of nitrobenzene and 9,10-anthraquinone derivatives

An attempt has been made to estimate the effect of the subsequent ion pairs formation on the value of theHammett reaction constant measured polarographically. To this purpose, the reduction ofpara-substituted nitrobenzenes and 2-substituted 9,10-anthraquinones was studied at a dropping mercury electrode in N,N-dimethylformamide. The ion pairs reaction constant of substituted nitrobenzene radical anions with tetraethylammonium cations is equal to –1.49 V/ unit. The corresponding reaction constant for the semiquinone—Li⁺ series was estimated to be –0.90 V/ unit. The method of calculation was based on the additivity rule withinHammett's treatment.

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Zur Additivität derHammet'schen Reaktionskonstanten. Paar-Effekte bei der polarographischen Reduktion von Nitrobenzol und 9,10-Anthrachinonderivaten

Zusammenfassung Es wurde eine Abschätzung des Effekts der nachfolgenden Ionenpaarbildung auf den polarographisch bestimmten Wert derHammet'schen Reaktionskonstanten versucht. Dazu wurde die Reduktion vonpara-substituierten Nitrobenzolen und 2-substituierten 9,10-Anthrachinonen an der tropfenden Quecksilberelektrode in N,N-Dimethylformamid untersucht. Die Ionenpaar-Reaktionskonstanten von substituierten Nitrobenzol-Radikalanionen mit Tetraethylammoniumkationen ist gleich –1.49 V/-Einheiten. Die ents prechende Reaktionskonstante für die Semichinon-Li⁺ Serie wurde mit –0.9 V/-Einheiten abgeschätzt. Die Berechnungsmethode basiert auf der Additivitätsregel derHammet'schen Reaktionskonstanten.

     

2-[1-(4-甲酰氨基苯基乙酰氧)烷基]-1,4-二羟基-9,10-蒽醌类衍生物的 合成及其抗肿瘤作用研究

为寻找抗肿瘤作用强、毒性低并且对癌细胞具有靶向性的新蒽醌类化合物, 合成了未见报道的12个2-[1-(4-甲酰氨苯基乙酰氧)烷基]-1,4-二羟基-9,10-蒽醌类衍生物, 分别用L1210癌细胞进行细胞毒性实验及小鼠S180腹水癌做了体内抗肿瘤实验. 实验结果表明, 蒽醌侧链中引入对甲酰氨基苯乙酰基后细胞毒性增强. 随着侧链碳链数的增加细胞毒性随之逐渐减小, 当烷基侧链中的碳数超过7以上时, 细胞毒性消失. 当侧链R基为苯环时与脂肪烃链或环己基相比细胞毒性更大, 说明芳香环对癌细胞具有更强的抑制作用. S180小鼠抗肿瘤实验结果表明, 蒽醌侧链中引入对甲酰氨基苯甲酰基后活性无显著性变化.     

Differential pulse anodic stripping voltammetric determination of lead(II) with a 1,4-bis(prop-2'-enyloxy)-9,10-anthraquinone modified carbon paste electrode

A sensitive and selective method for the determination of lead(II) with a 1,4-bis(prop-2'-enyloxy)-9,10-anthraquinone (AQ) modified carbon paste electrode has been developed. The method is based on non-electrolytic preconcentration via complex formation with modifier, followed by an accumulation period with a negative potential (-1.5 V), and then by a proper anodic stripping. The analytical performance was evaluated with respect to the quantity of modifier in the paste, concentration of electrolyte solution, preconcentration time, lead(II) concentration, and other variables. A linear calibration graph was obtained in the concentration range 2.00x10(-9)-1.06x10(-5) M Pb(II) (n=21, r=0.9999) with 30 s preconcentration time. The detection limit was found to be 1x10(-9) M. For eight preconcentration/determination cycles, the differential pulse voltammetric response was reproduced with 5.0 and 3.7% relative standard deviations at 2.00x10(-8) and 2.00x10(-6) M Pb(II), respectively. Rapid and convenient renewal of electrode surface allows the use of a single modified electrode surface in multiple analytical determinations over several weeks. Many coexisting metal ions had little or no effect on the determination of lead(II). The developed method was applied to lead determination in waste waters.     

Further evidence for the intramolecular charge-transfer interaction between tropylium ion and remote benzene rings in 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborate and its methyl derivatives

A series of 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborates

has been prepared. The intramolecular charge-transfer interactions in

were confirmed by their UV spectra and pK_R+ values. As a model compound 1,2,3,4-tetrahydro-1,4-(1,2-tropylio)naphthalene tetrafluoroborate ($\text{5}$)_was also examined.     

High-performance liquid chromatographic determination of the 1,4-diketo and 1,4-diketo-2,3-dihydroxy metabolites of lonapalene in rat urine

Individual high-performance liquid chromatographic (HPLC) methods have been developed for the determination of two major metabolites of lonapalene in rat urine. The highly unstable and polar 1,4-diketo-2,3-dihydroxy metabolite (II) is extracted from urine by two extraction columns (phenyl followed by silica), further purified by means of HPLC with a fully end-capped C18 HPLC column and quantified by an ultraviolet detector at 280 nm. Ascorbic acid is used as an antioxidant during extraction and overnight injection of II. Urine samples for total II (free plus conjugated) determination are incubated with arylsulfatase and beta-glucuronadase prior to extraction. The 1,4-diketo metabolite (III) is extracted from urine with a C18 extraction column, further purified with a C18 HPLC column, and quantified by an ultraviolet detector at 260 nm. The detection limit for both metabolites is 100 ng/ml of urine (signal-to-noise = 2.5). The methods were used to analyze urine samples from a long-term toxicology study of lonapalene in rats and to determine the linearity of dose-concentration relationships for both metabolites.     

Use of multivariate curve resolution analysis in the spectroelectrochemistry of 9,10-anthraquinone reduction in dimethylformamide solution

A multivariate curve resolution analysis has been conducted to deconvolute the spectroelectrochemical data of 9,10-anthraquinone (AQ) reduction. The experiments were carried out in dimethylformamide solution containing small amounts of benzoic acid as a proton source at an optically transparent thin layer electrode (OTTLE). Two electrochemical techniques, namely a potential step method and chronoabsorptiometry were employed. In the former, the absorbance spectra of anthraquinone solutions at different applied potentials were recorded, and in the latter technique, a −1.90 V potential was applied to the OTTLE and the absorbance spectra of the solution were recorded at different time intervals. For both techniques, factor analysis revealed that three chemical components coexist in the system, which can be attributed to AQ⁻, AQH⁻ and AQ²⁻. By using a multivariate curve resolution analysis, the concentration profiles and pure spectra of the components were determined. The results of the potential step method revealed that the maximum amount of AQ⁻ is produced at −1.25 V, and application of more negative potentials causes an decreased amount of AQ⁻ at the expense of the evolution of AQH⁻. Finally, the AQ²⁻ species is produced at −1.6 V. The chronoabsorptiometric results showed that AQ⁻ is not stable at 1.9 V and rapidly converts to AQ²⁻.     

Photoreduction of 9,10-anthraquinone derivatives: transient spectroscopy and effects of alcohols and amines on reactivity in solution

The photoreduction of 9,10-anthraquinone (AQ), the 2-methyl, 2-ethyl, 2,3-dimethyl, 1,4-difluoro, 1-chloro and 1,8-dichloro derivatives as well as 1,4,4a,9a-tetrahydroanthraquinone, 1,2-benzanthraquinone and 6,13-pentacenequinone in nonaqueous solution at room temperature was studied by time-resolved UV-visible spectroscopy. Upon 308 nm excitation of AQ the triplet state reacts with alcohols and triethylamine (TEA). The rate constant of triplet quenching by amines is close to the diffusion-controlled limit. The semiquinone radical *QH/ Q*- is the main intermediate, and the half-life of the second-order decay kinetics depends significantly on the donor and the medium. Photoinduced charge separation after electron transfer from amines to the triplet state of AQ in acetonitrile and the subsequent charge recombination or neutralization also were measured by transient conductivity. The maximum quantum yield, lambdairr = 254 nm, of photoconversion into the strongly fluorescing 9,10-dihydroxyanthracenes is close to unity. The fluorescence with maximum at 460-480 nm and a lifetime of 20-30 ns disappears as a result of a complete recovery into AQ, when the dihydroxyanthracenes are exposed to oxygen. The mechanisms of photoreduction of parent AQ in acetonitrile by 2-propanol and in benzene and acetonitrile by TEA are discussed. The effects of AQ follow essentially the same pattern. The various functions of oxygen, e.g. (1) quenching of the triplet state; (2) quenching of the semiquinone radical, thereby forming HO2*/O2*- radicals; and (3) trapping of the dihydroxyanthracenes are outlined.