由2-羟基-1,4-萘醌合成2-乙氧基-1,4-萘醌

由2-羟基-1;4-萘醌合成2-乙氧基-1;4-萘醌;乙氧基萘醌; 羟基萘醌; 乙醇; 硝酸; 回流     

金属卟啉催化氧化萘酚 Ⅰ.2-羟基-1,4-萘醌的制备

羟基萘醌;金属卟啉催化氧化萘酚 Ⅰ.2-羟基-1;4-萘醌的制备     

2-羟基-1,4-萘醌的合成及铁卟啉-氧催化中间体形成平衡常数的测定

铁卟啉催化剂;羟基萘醌;2-羟基-1;4-萘醌的合成及铁卟啉-氧催化中间体形成平衡常数的测定     

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.     

金属卟啉催化萘酚过氧化氢氧化(Ⅱ)──制备2-羟基-1,4-萘醌的氧化机理研究

在低温碱性甲醇溶液中一氯化四苯基卟啉铁催化萘酚H₂O₂氧化高选择性地制取2-羟基-1,4-萘醌(HNQ),以2-萘酚和1-萘酚为底物时HNQ的最高产率分别为57%和40%(纯度>95%).根据金属卟啉催化氧化反应的特性,采用UV-Vis和EPR现场光谱监测催化剂和反应物的光谱变化,提出了羟基游离基加成反应机理.     

1,2-萘醌-4-磺酸钠试剂分光光度法测定葡萄糖

建立了用1, 2-萘醌-4-磺酸钠测定葡萄糖的新方法. 研究表明, 在pH 13.00的缓冲溶液中, 葡萄糖能够催化1,2-萘醌-4-磺酸钠与OH-反应生成2-羟基-1, 4-萘醌, 其最大吸收波长为454 nm. 葡萄糖质量浓度在0.8～80 mg/L范围内, 呈现良好线性关系. 线性回归方程为A＝0.0165+0.01004c(10-5 mol/L), 线性相关系数r＝0.9985. RSD和检出限分别为0.92%, 0.7 mg/L. 该法能够直接用于注射液中葡萄糖含量的测定.     

1,2-萘醌-4-磺酸钠体系分光光度法测定对苯二酚

建立了用1,2-萘醌-4-磺酸钠分光光度法测定对苯二酚的新方法. 研究表明,在pH=13.00的KCl-NaOH缓冲溶液中,对苯二酚能够催化溶液中的OH-离子与1,2-萘醌-4-磺酸钠反应形成橙红色的2-羟基-1,4-萘醌,其最大吸收波长为454 nm. 对苯二酚质量浓度在1.3×10-7～1.32×10-5 g/mL范围内与吸光度呈现良好的线性关系. 线性回归方程为A=0.025 61+0.073 28c(1×105 mol/L),线性相关系数r=0.995 5,检测限为9×10-8 g/mL. 方法能直接用于水样中对苯二酚含量的测定,回收率在96.5%～103%.     

1, 2-萘醌-4-磺酸钠分光光度法测定间苯二酚

在pH 13.00缓冲溶液中, 间苯二酚能够催化氢氧根离子与1,2-萘醌-4-磺酸钠反应生成2-羟基-1, 4-萘醌, 其最大吸收波长为454 nm. 间苯二酚质量浓度在0.39～13.21 mg/L范围内与吸光度呈现良好线性关系. 线性回归方程为A=0.01918+0.05703c (×105 mol/L), 相关系数r=0.9981. RSD和检测限分别为1.6%, 0.34 mg/L (3σ/k). 该法能够直接用于水样中间苯二酚含量测定, 回收率在94.3%～106%.     

1,2-萘醌-4-磺酸钠测定盐酸吡硫醇的研究

建立了1,2-萘醌-4-磺酸钠分光光度法测定含羟基药物盐酸吡硫醇的方法.研究表明,在pH=13.00的KCl-NaOH缓冲溶液中,盐酸吡硫醇能够催化氢氧根离子与1,2-萘醌-4-磺酸钠反应形成橙红色的2-羟基-1,4-萘醌,其最大吸收波长为454nm.盐酸吡硫醇浓度在3.2μg/mL～80μg/mL范围内与吸光度呈现良好的线性关系.线性回归方程为A＝0.02715+0.02837C(×105 mol/L),线性相关系数r＝0.9986.表观摩尔吸光系数、相对标准偏差(R.S.D.)和检测限分别为2.84×103L/mol/cm、1.6%和2.0μg/mL.通过对片剂中的盐酸吡硫醇含量进行测定,回收率在98%～101%.     

1,2-和1,4-萘醌248 nm激光光解的瞬态吸收光谱研究

利用纳秒级激光光解动态吸收光谱装置,研究了1,2-和1,4-萘醌中性水溶液的瞬态吸收光谱.发现1,2-萘醌及1,4-萘醌被光电离后形成的阳离子自由基在380nm均有最大吸收,但1,4-萘醌阳离子自由基在衰变过程中又形成了两种新的活性粒子,它们的最大吸收分别位于410和580nm,分析表明:410nm属于1,4-萘醌脱氢自由基的吸收,而580nm很可能归属由于电子转移而形成的瞬态产物.进一步研究发现,1,2-萘醌在中性水溶液中能被248nm激光单光子电离.     

Catalytic Oxidative Conversion from Naphthol to 2-Hydroxy-1, 4-naphthoquinone over Iron Porphyrin Catalysts by Molecular Oxygen in an Alkaline 2-Propanol Solution

In an alkaline 2-propanol solution with 5, 10,15,20-tetra (4-methoxyl phenyl) porphyrin iron chloride (TOMPPFeCl) as a catalyst and oxygen as a cheap green oxidant, 2-naphthol was conversed to 2-hydroxy-1 ,4-naphthoquinone(HNQ) with a yield of 62. 17% and a selectivity of 100%, and the conversion number of TMOPPFeCl catalyst was 8.32/min. The catalytic oxidation products were characterized by means of UVVis, IR, GC-MS, ^1H NMR and melting point determination. In this catalytic oxidation, the catalytic activity of TMOPPFeCl was researched in detail and the reacting conditions were optimized. A possible reaction mechanism is summarized based on in situ EPR determination.     

Kinetic Studies on Interactions of Ferreous-porphyrins with Hydrogen Peroxide

In an alkali-methanol solution, both 1- and 2-naphthol can be converted into 2-hydroxy-l,4-naphtho-quinone (HNQ) with selectivity more than 95% by H2O2 over metalloporphyrin catalyst. The UV-Vis spectra indicate that a high valence oxygen-ferreous porphyrin intermediate has been produced by addition of an aqueous solution of H2O2 into the catalytic system. This intermediate formation rate is influenced by the concentrations of low valence ferrous porphyrin H2O2, and NaOH existing in the system. With the aid of the UVVis spectrum varieties, the rate equations and formation rate constants of the intermediate at different temperatures can be determined by changing the original concentration of each reactant. The formation activation energy of this intermediate was also determined by changing temperature.     

Catalytic Conversion of 2-Naphthol to 2-Hydroxy-1,4-naphthoquinone Under Mild Conditions

Introduction 2-Hydroxy-1,4-naphthoquinone (HNQ), existing in natural plants,1,2 is popularly separated and purified as dye or pigment. Recent research results show that, with the function to prevent the formation of protein coenzyme of HIV-I, HNQ can inhibit HIV virus from copying and propagating,3,4 HNQs derivatives and di-chloroallyl lawsone are also the inhibitor for RNA syn-thesis of cancer.5 It is well known that there is a rela-tionship between the side chain attached to HNQ an…     

Formal hydride transfer mechanism for photoreduction of 3-phenylquinoxalin-2-ones by amines. Association Of 3-phenylquinoxalin-2-one with aliphatic amines

The photophysical and photochemical behavior of 1-methyl-3-phenylquinoxalin-2-one (MeNQ) and 3-phenylquinoxalin-2-one (HNQ) in the presence of amines is reported. While HNQ fluorescence shows an auxochromic effect and a bathochromic shift with added amines, explained by association of HNQ with amine in the ground state and emission from both excited species HNQ and [HNQ-amine], both MeNQ and HNQ are photoreduced efficiently on irradiation in the presence of amines, leading to the semireduced quinoxalin-2-ones, MeNQH(-) and HNQH(-), respectively, via an electron-proton-electron transfer, with unit quantum yields at high amine concentrations. The semireduced quinoxalin-2-ones XNQH(-) (X = H, Me) revert almost quantitatively to the parent XNQ in a dark thermal reaction with an activation free energy for MeNQH(-) of 17.4 and 25.9 kcal/mol in acetonitrile and benzene, respectively. Kinetic and spectroscopic (UV and NMR) evidence supports the proposed reaction mechanism for the reversible photoreduction.     

Theoretical studies of conjugation and substituent effect on intramolecular proton transfer in the ground and excited states

The ground- and excited-state intramolecular proton transfer (GSIPT and ESIPT) for 8-hydroxy-4H-naphthalen-1-one (HNA), 5-hydroxynaphthoquinone (HNQ), 1-hydroxy-anthraquione (HAQ), 7-hydroxy-1-indenone (7HIN), 5,8-dihydroxynaphthoquinone (DHNQ) and 4,9-dihydroxyperylene-3,10-quinone (DHP) are studied at B3LYP/6-31G(d,p) and TD B3LYP/6-31G(d,p) level. The calculated results show that the PES of GSIPT for HNA, HNQ and HAQ exhibit a single minimum in the enol zone, while for 7-HIN, DHNQ and DHP exhibit a double minimum and a high barrier between the two minima. The barrierless ESIPT for HNA is predicted, however, the PES of ESIPT for HNQ, HAQ, 7HIN, DHNQ and DHP exhibit a high barrier in the S₁ tautomerism.     

Kinetic and Spectroscopic Characterization of 1-Naphthol 2-hydroxylase from Pseudomonas sp. Strain C5

1-Naphthol 2-hydroxylase (1-NH) catalyzes the conversion of 1-naphthol to 1,2-dihydroxynaphthalene. 1-NH from carbaryl degrading Pseudomonas strain C5 was purified and characterized for its kinetic and spectroscopic properties. The enzyme was found to be NAD(P)H-dependent external flavin monooxygenase. Though the kinetic parameters of 1-NH from strain C5 appear to be similar to 1-NH enzyme from strains C4 and C6, however, they differ in their N-terminal sequences, mole content of flavin adenine dinucleotide (FAD), reconstitution of apoenzyme, and K _i. 1-NH showed narrow substrate specificity with comparable hydroxylation efficiency on 1-naphthol and 5-amino 1-naphthol (~30 %) followed by 4-chloro 1-naphthol (~9 %). Salicylate was found to be the nonsubstrate effector. The flavin fluorescence of 1-NH was found to increase in the presence of 1-naphthol (K _d?=?11.3 μM) and salicylate (K _d?=?1027 μM). The circular dichroism (CD) spectra showed significant perturbations in the presence of NAD(P)H, whereas no changes were observed in the presence of 1-naphthol. Naphthalene, 1-chloronaphthalene, 2-napthol, and 2-naphthoic acid were found to be the mixed inhibitors. Chemical modification studies showed the probable involvement of His, Cys, and Tyr in the binding of 1-naphthol, whereas Trp was found to be involved in the binding of NAD(P)H.     

Ionic liquid-based dispersive liquid-liquid microextraction with back-extraction coupled with capillary electrophoresis to determine phenolic compounds

Ionic liquid (IL) based dispersive liquid-liquid microextraction (DLLME) with back-extraction coupled with capillary electrophoresis ultraviolet detection was developed to determine four phenolic compounds (bisphenol-A, β-naphthol, α-naphthol, 2, 4-dichlorophenol) in aqueous cosmetics. The developed method was used to preconcentrate and clean up the four phenolic compounds including two steps. The analytes were transferred into room temperature ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [C(8) MIM][PF(6) ]) rich-phase in the first step. In the second step, the analytes were back-extracted into the alkaline aqueous phase. The effects of extraction parameters, such as type and volume of extraction solvent, type and volume of disperser, extraction and centrifugal time, sample pH, salt addition, and concentration and volume of NaOH in back-extraction were investigated. Under the optimal experimental conditions, the preconcentration factors were 60.1 for bisphenol-A, 52.7 for β-naphthol, 49.2 for α-naphthol, and 18.0 for 2, 4-dichlorophenol. The limits of detection for bisphenol-A, β-naphthol, α-naphthol and 2, 4-dichlorophenol were 5, 5, 8, and 100 ng mL(-1), respectively. Four kinds of aqueous cosmetics including toner, soften lotion, make-up remover, and perfume were analyzed and yielded recoveries ranging from 81.6% to 119.4%. The main advantages of the proposed method are quick, easy, cheap, and effective.     

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.     

Ab initio and semiempirical study of structure and electronic spectra of hydroxy substituted naphthoquinones

The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquinone (2HNQ), 5-hydroxy-1,4-naphthoquinone (5HNQ), and 5,8-dihydroxy-1,4-naphthoquinone (DHNQ), have been optimized using the semiempirical and ab initio theoretical methods. Semiempirical methods used for the optimization are Austin Model 1 (AM1) and Zerner's Intermediate Neglect of Differential Overlap/1(ZINDO/1). For ab initio calculations the 6-31G* basis set is used. The electronic spectra of 1,4-naphthoquinone and its hydroxy derivatives are calculated using the semiempirical Zerner's Intermediate Neglect of Differential Overlap/Spectroscopy (ZINDO/S) method employing the geometries optimized at AM1, ZINDO/1 and ab initio levels and compared with their electronic absorption spectra measured by us. For hydroxy substituted systems, such calculations for spectral assignments are made for the first time. It is found that though the predictions of the three theoretical methods for the geometries are similar, the predictions of the ZINDO/S method using the ZINDO/1 optimized geometries, are better for the transition wavelengths in the visible region of the hydroxy substituted naphthoquinones, especially for 5HNQ and DHNQ.