2,6-二甲氧基-3-烷基-1,4-苯醌的合成

取代的1,4-苯醌类化合物广泛存在于自然界的植物和动物体内。其中有一部分已证明具有明显生理活性。最重要的取代1,4苯-醌类化合物是泛醌(ubiquinone)和质体醌(plastoquinone)。它们是动物线粒体呼吸链和植物光合作用链中重要的非蛋白电子载体。2,6-二甲氧基-1,4-苯醌(4)存在于许多植物的树皮和木心中。它的生理作用目前还知道得     

甲基蓝双波长光度法测定阿米卡星

在酸性条件下,甲基蓝(MB)与阿米卡星(AMK)反应,生成蓝色离子缔合物,最大吸收波长和负吸收波长分别位于616 nm和676 nm,正负峰吸光度绝对值之和与AMK的浓度线性相关,AMK的浓度在0～1.5×10~(-5)mol·L~(-1)范围内遵从比耳定律,表观摩尔吸光系数ε为7.28×10~4L·mol~(-1)·cm~(-1),据此建立了测定阿米卡星的甲基蓝双波长光度法。方法用于市售药物及人体尿液中阿米卡星含量的测定,结果满意。     

曙红Y分光光度法测定阳离子表面活性剂及其机理研究

在弱酸性的HCl-NaAc缓冲介质中,阳离子表面活性剂(CS)与曙红Y(EY)染料反应,形成离子缔合物,溶液颜色发生明显改变,最大褪色波长分别在514 nm(EY-CPB体系)、516 nm(EY-CTAB体系),同时在548 nm(CPB体系)、544 nm(CTAB体系)处有吸收峰,在褪色波长处阳离子表面活性剂的浓度与褪色程度呈良好线性关系,从而建立测定阳离子表面活性剂的光度法。在最大褪色波长处,CPB体系、CTAB体系中CS的浓度在0~4.79×10-5mol/L、0~2.90×10-5mol/L范围内遵守比尔定律,表观摩尔吸光系数为2.94×104、2.86×104L.mol-1.cm-1,检出限为8.97×10-7mol/L、7.87×10-7mol/L。若用双波长叠加,表观摩尔吸光系数达5.58×104、5.20×104L.mol-1.cm-1,检出限为5.87×10-7、6.25×10-7mol/L。方法适用于水样中CS的测定。本文还用密度泛函理论对反应机理进行了探讨。     

刚果红褪色光度法测定盐酸西布曲明及作用机理研究

在弱酸性NaH_2PO_4-Na_2HPO_4的缓冲介质中,盐酸西布曲明与刚果红染料反应,形成离子缔合物,溶液颜色发生明显改变,褪色波长在342nm、490nm,其中最大褪色波长在490nm,从而建立了测定盐酸西布曲明的光度法。在最大褪色波长处,盐酸西布曲明的浓度在0.35~3.2×10-5mol/L范围内遵守比尔定律;表观摩尔吸光系数ε490为1.67×104L·mol-1·cm-1;检出限为4.45×10-7mol/L。方法具有较高的灵敏度和良好的选择性,用于曲美胶囊中盐酸西布曲明的测定,结果满意。本实验还用密度泛函理论对反应机理进行了探讨,结果与实验结果相符合。     

亚甲基蓝光度法测定西地那非的含量

在pH3.0～6.0的条件下,亚甲基蓝(MB)与西地那非(SD)反应,生成蓝色离子缔合物,最大吸收波长位于600nm,SD浓度在0～1.6×10-5mol/L范围服从比耳定律,由此建立了测定西地那非含量的分光光度法。缔合物的表观摩尔吸光系数(ε)为3.0×104L·mol-1·cm-1。该方法用于市售药物中西地那非含量的测定,结果满意。     

有机胺与醌类化合物电荷转移络合物的研究

研究了二异丙胺(DIPA)、2,2,6,6—四甲基—4—羟基啶(TMHP)与四氯苯醌(CA)、苯醌(BQ)在一些溶剂形成电荷转移络合物(CTC)的反应。结果表明:DTPA—CA呈色较快,生成的CTC紫外光谱λ_(CTC)吸收值变化大。在环已烷中分离出N-取代产物。用甲醇作溶剂,则得到2,3,5,6-四甲氧基-1.4-苯醌(TMOBQ)。文中还用电子自旋共振谱,证实了CTC中存在醌负离子自由间体。     

IO3--I--亚甲基蓝-阿拉伯胶-聚乙烯醇体系分光光度法测定微量碘

在pH 3.8苯二甲酸氢钾-盐酸介质中,有阿拉伯胶和聚乙烯醇存在下,IO-3氧化I-生成I-3,I-3再与亚甲基蓝形成离子缔合物,缔合物的最大吸收波长为525 nm,表观摩尔吸光系数ε525＝1.32×105 L/(mol·cm),IO-3浓度在0～30 μg/25 mL范围内服从比尔定律. 方法用于碘盐和生物样品中碘的测定,结果满意.     

溴酚蓝光度法测定马来酸罗格列酮的含量

在pH 4.50的Britton-Robinson(B-R)缓冲溶液中,溴酚蓝(BPB)与马来酸罗格列酮(ROM)反应,形成1∶1的离子缔合物,溶液颜色明显发生改变,最大吸收波长为434 nm,同时在波长590 nm处产生负吸收.在590 nm处,马来酸罗格列酮浓度分别在0～1.70×10-5 moL/L范围遵循比尔定律,表观摩尔吸光系数ε590为4.51×104 L/(mol·cm),检出限为2.60×10-7 mol/L.方法可用于分析检测马来酸罗格列酮的含量.     

1,4-苯醌衍生物的合成、氧化还原电位和生物活性的研究

合成了一系列具有不同的醌环结构(醌环上的取代基不同,如甲基、甲氧基、氢、氯和溴,或取代基的排列位置不同)的6-正癸基-1,4-苯醌衍生物。系统地研究了它们的结构、氧化还原电位和在线粒体琥珀酸-细胞色素 c 氧化还原晦中生物功能的关系。     

2,1,3-苯并硒二唑与联苯二胺类共轭共聚物的金属催化法合成与表征

利用金属催化法分别合成出了2,1,3-苯并硒二唑与N,N′-二氯联苯醌二亚胺、3,3′-二甲基-N,N′-二氯联苯醌二亚胺,3,3′-二甲氧基-N,N′-二氯联苯醌二亚胺的共轭交替共聚物:聚(N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑),聚(3,3′-二甲基-N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑),聚(3,3′-二甲氧基-N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑)。利用凝胶色谱(GPC)、红外光谱、紫外可见光谱以及循环伏安(CV)等对这三种共聚物进行了表征和性能研究。紫外可见光谱分析结果表明,这三种共聚物分别在305nm、421nm,325nm、438nm和330nm、558nm处出现吸收峰,但由于受侧基的影响,聚(3,3′-二甲氧基-N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑)相对于聚(N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑)和聚(3,3′-二甲基-N,N′-联苯醌二亚胺-2,1,3-苯并硒二唑)的共轭程度要高,而且共聚物链上的侧基对其电化学性能也有一定的影响。     

Microwave-mediated Claisen rearrangement followed by phenol oxidation: a simple route to naturally occurring 1,4-benzoquinones. The first syntheses of verapliquinones A and B and panicein A

The naturally occurring 1,4-benzoquinones 2-methoxy-6-propyl-1,4-benzoquinone (1), 2-methoxy-6-pentyl-1,4-benzoquinone (primin 2), 2-methoxy-6-pentadecyl-1,4-benzoquinone (3), 2-methoxy-6-heptadecyl-1,4-benzoquinone (dihydroirisquinone, pallasone B; 4) were synthesized by a simple protocol involving microwave accelerated Claisen rearrangement of allyl ethers 10, followed by hydrogenation of the side chain alkene, and oxidation to the quinone. The Claisen-based methodology was extended to the first synthesis of the marine benzoquinones verapliquinones A and B (5 and 6), and panicein A (7). Isoarnebifuranone (9) was also synthesized by a similar strategy.     

Synthesis and properties of dipyridinium betaines of derivatives of 1,4-benzoquinone and tetracyanoquinodimethane

Reaction of chloranil with excess pyridine gives the poorly stable 2,5-di(N-pyridinium)-3,6-dichloro-1,4-benzoquinone dichloride which is readily hydrolyzed to give the bisbetaine of 2,5-di(N-pyridinium)-1,4-benzoquinone-3,6-dioxide. Treatment with acid gives its mono- and bisprotonated derivatives as the perchlorate and dibromide and bromination gives the betaine 2-bromo-2,5-di(N-pyridinium)-5-cyclohexene-1,3,4-trione-6-oxide perbromide. The reaction of malonodinitrile with 2,5-di(N-pyridinium)-3,6-dichloro-1,4-benzoquinone dichloride in situ gives the poorly stable bisbetaine of 2,5-di(N-pyridinium)-7,7,8,8-tetracyanoquinodimethane-3,6-dioxide.Riga Technical University, Riga LV-1048. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 346–349, March, 1998.     

Synthesis of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-r-benzimidazoles

Reaction of 2,6-di-tert-butyl-1,4-benzoquinone with o-phenylendiamine gives 2,6-di-tert-butyl-1,4-benzoquinone-4-(N-o-aminophenyl)imine which reacts smoothly with heterocyclic, aromatic and aliphatic aldehydes to form (1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-substituted benzimidazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–485, April, 1990.     

Photoinduced self-substitution of haloquinones

A series of novel oligo(halobenzoquinoid) compounds have been obtained from the photoinduced self-substitution of 2,5-dibromo-1,4-benzoquinone (1a), 2,6-dibromo-1,4-benzoquinone (1b), 2-chloro-1,4-benzoquinone (1c), 2-bromo-5-chloro-1,4-benzoquinone (1d), 2,3,5,6-tetrachloro-1,4-benzoquinone (1e) and 1,4-benzoquinone (1f) in the presence of N,N-dimethyl-t-butylamine (2) in acetonitrile. Dimers, trimers and/or pentamers of these haloquinones were found to be the major products.     

Spectrophotometric assay of yeast vitality using 2,3,5,6-tetramethyl-1,4-benzoquinone and tetrazolium salts.

A method for the spectrophotometric assay of yeast vitality was developed using 2,3,5,6-tetramethyl-1,4-benzoquinone and tetrazolium salts. The metabolic efficiency of 2,3,5,6-tetramethyl-1,4-benzoquinone by yeast cells was used as an index of yeast vitality. 2,3,5,6-Tetramethyl-1,4-benzoquinone was reduced to 2,3,5,6-tetramethyl-1,4-hydroquinone by yeast cells. Then, the superoxide anion radicals generated from O2 by reduction with 2,3,5,6-tetramethyl-1,4-hydroquinone under alkaline conditions reduced tetrazolium salts to formazan, which exhibited absorbance maxima at 440 nm. A linear relationship between the absorbance and viable cell density was obtained in the range of 1.0 x 10(5)-2.0 x 10(7) cells/ml for a sample solution. During the cultivation of yeast cells, the absorbance showed almost an anti-parallel change with that of glucose in yeast growth and fermentation, suggesting that the absorbance change reflected the vitality of yeast cells.     

Palladium (II) Assisted Preparation of Methoxyarylbenzoquinones

The reaction of 2-methoxy-1,4-benzoquinone with methoxyphenolic derivative compounds obtained from wood tar constituents, assisted by palladium (II) acetate in acetic acid, allowed the preparation of five novel methoxyaryl-substituted 1,4-benzoquinones, as well as four structural isomer mixtures.     

Synthesis of mimosamycin

Mimosamycin (1) was synthesized in eight steps with an overall yield of 13% from 2-methoxy-3-methyl-1,4-benzoquinone by regioselective introduction of a chloromethyl group at C-6 and a methoxycarbonylmethyl group at C-5 and subsequent reaction of the intermediate methyl (o-(chloromethyl)phenyl)acetate derivative 16 with methylamine. Oxidation of the 5,7,8-trimethoxy-2,6-dimethyl-1, 4-dihydroisoquinoline-3(2H)-one 17 thus obtained, using cerium(IV) ammonium nitrate as a selective oxidizing agent, gave mimosamycin (1) in good overall yield.     

Crystal engineering using anilic acids and dipyridyl compounds through a new supramolecular synthon

The anilic acids, 2,5-dihydroxy-1,4-benzoquinone (1a), 2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone (bromanilic acid; 1b), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid; 1c), and 2,5-dicyano-3,6-dihydroxy-1,4-benzoquinone (cyananilic acid; 1d), were cocrystallized with rigid organic ligands containing two pyridine rings, 2,4-bipyridine (2a), 4,4'-bipyridine (2b), 1,2-bis(2-pyridyl)ethylene (3a), 1,2-bis(4-pyridyl)ethylene (3b), 2,2'-dipyridylacetylene (4a), 3,3'-dipyridylacetylene (4b), and 4,4'-dipyridylacetylene (4c). Fourteen complexes 5-18 were obtained as single crystals, and their crystal structures were successfully determined by X-ray analysis. All complexes except those with 2a are 1:1 and are composed of an infinite linear or zigzag tape structure, the formation of which is ascribed to intermolecular O-H...N, N(+)-H...O, or N(+)-H...O(-) hydrogen bonds or a combination of these between the anilic acids and the dipyridyl compounds. In the complexes 5 and 6, no infinite tape structure is observed although the molecular units connected by a similar hydrogen-bonding pattern are formed. For the 1:1 complexes, we have found two types of stacking arrangements, segregated stacks (7, 9, 12-15, 18) and alternated ones (8, 10, 11, 16, 17). In the complexes of 1c with the series of dipyridylacetylenes 4 (14, 15, 17), the neutral, dication, and monocaction states are formed depending on the nitrogen positions, which can be attributed to the different basicity of the pyridyl groups.     

Oxidation of lignin model compounds in water with dioxygen and hydrogen peroxide catalysed by metallophthalocyanines

Water-soluble metallophthalocyanines and metalloporphyrins were tested as catalysts for the aqueous oxidations of 3,4-dimethoxybenzyl alcohol (1), 4-hydroxy-3-methoxytoluene (3) and 3,4-dimethoxytoluene (8) with dioxygen and with hydrogen peroxide. Cobalt phthalocyaninetetra(sodium sulfonate) (CoPcTS) catalysed the reactions of dioxygen with 1 to form only 3,4-dimethoxybenzaldehyde (2) and with 3 to form 2,2′-dihydroxy-3,3′-dimethoxy-5,5′-dimethylbiphenyl (4) and other, unidentified products at 70–85 °C and pH ⩾ 8, while the other catalysts were inactive. The most active catalyst for the oxidations of 1, 3 and 8 with hydrogen peroxide was FePcTS in acidic solution: alcohol 1 produced aldehyde 2 and 2-hydroxymethyl-5-methoxy-1,4-benzoquinone; phenol 3 produced dimer 4, 3-methoxy-4-hydroxybenzyl alcohol and a dimer with one hydroxymethyl group; 3,4-dimethoxytoluene (8) produced 2-methyl-5-methoxy-1,4-benzoquinone. Cationic latex particles had little effect on the oxidations.     

A new alkylated benzoquinone from rhizomes of Iris kumaonensis

A novel alkylated unsaturated p-benzoquinone designated as 3-[(z)-12'-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone was isolated from hexane extract of the rhizomes of Iris kumaonensis and it's structure was confirmed by extensive spectroscopic analysis, IR, MS, HREIMS, 1D, 2D NMR and comparison with the literature data of known compounds.