光控化学振荡器的设计(英文)

This article reviewed recent progresses in the design of a new class of chemical oscillators and developed a generic model that could qualitatively reproduce those photochemical oscillations seen in experiments. The two oscillators discussed in this report are based on the photolysis of 1,4-benzoquinone and its derivatives, in which external illumination is vital in initiating and sustaining the reaction processes. Nonlinear behavior in these two photo-controlled chemical oscillators are analyzed as a function of light intensity and the initial concentration of reagents including 1,4-benzoquinone, 1,4-hydroquinone, 2-methyl-1,4-benzoquinone, bromate, and sulfuric acid. A generic model proposed initially for the uncatalyzed bromate-aromatic compound reactions was modified here to account for the photolysis of 1,4-benzoquinone or 2-methyl-1,4-benzoquinone. The modified model qualitatively reproduced chemical oscillations and their dependence on light intensity.     

The 1,4-cyclohexanedione-bromate-acid oscillatory system I. Its organic chemistry

The organic chemistry of the 1,4-cyclohexanedione (CHD)-bromate-sulfuric acid oscillatory system has been revealed by following the reaction of 1,4-CHD with bromate using a GC/MS technique. We could identify 1,4-dihydroxybenzene as an intermediate, 1,4-benzoquinone as the main oxidation, and mono- and dibromocyclohexanedione as the main bromination products. Acid bromate does not cleave the alicyclic ring.     

Reaction of 1,4-benzoquinones with PH-phosphonium salts

A novel approach has been proposed to the synthesis of phosphonium salts containing a 1,4-dihydroxybenzo fragment via reaction of 2-methyl-1,4-benzoquinone or 2-isopropyl-5-methyl-1,4-benzoquinone with PH-phosphonium salts generated in situ from triphenylphosphine and trifluoromethanesulfonic or trifluoroacetic acid. The structure of the synthesized phosphonium salts was determined by NMR spectroscopy and X-ray analysis.     

Reactivity of N-arylsulfonyl-1,4-benzoquinone imines. Reaction with hydrazoic acid

N-Arylsulfonyl-2-halo-1,4-benzoquinone imines react with hydrazoic acid in boiling acetic acid via two pathways: the 1,4-addition and nucleophilic replacement of the halogen atom by an azido group, followed by the 1,4-addition of HN₃. In the reaction of N-arylsulfonyl-2,6-dihalo-1,4-benzoquinone imines with hydrazoic acid, both halogen atoms are replaced by azido groups, while N-p-tolylsulfonyl-2-methyl-1,4-benzoquinone imine takes up HN₃ molecule according to the 1,4-addition pattern.     

An investigation of oxidative animation of 2-methyl-1,4-benzoquinone with pyrrolidine

Oxidative amination of 2-methyl-1,4-benzoquinone with pyrrolidine yielded 2-methyl-6-pyrrolidino-1,4-benzoquinone as the major product along with 2-methyl-5-pyrrolidino-1,4-benzoquinone formed as the minor product. No detectable amount of 2-methyl-3,6-bis-(pyrrolidino)-1,4-benzoquinone was observed.     

Complex dynamical behavior in the highly photosensitive cerium-bromate-1,4-benzoquinone reaction

Experimental and numerical investigations are carried out on the nonlinear dynamics of the cerium-bromate-1,4-benzoquinone reaction in which a unique kinetic feature is that the reduction of Ce(IV) is through bromide ions rather than by organic substrates. Nonlinear phenomena including both simple and sequential oscillations have been observed, and the system could oscillate for longer than a week. Significantly, fluorescent ceiling light with an intensity of less than 20 μW/cm(2) exhibited strong influence on the frequency, lifetime, and complexity of the spontaneous oscillations. The transient oscillations lasted for a longer period of time at a low light intensity, were quenched by a moderate illumination, and then became long-lived again at a higher light intensity. Characterizations with (1)H NMR and GC/MS spectroscopy and ion selective electrode suggest that 2-bromo-1,4-benzoquinone is an important unstable intermediate product that undergoes photoaccelerated decomposition to produce hydroxy-1,4-benzoquinone and bromide ions. Simulations successfully reproduced the occurrence of oscillatory behavior in the studied system.     

利用Diels-Alder反应构建桉烷类倍半萜骨架关键中间体的研究

以3-甲基-1,3-间苯二酚和异戊醛为原料分别合成亲双烯2-甲氧基-6-甲基对苯醌和双烯1-甲氧基-3-异丙基-1,3-丁二烯,通过Diels-Alder反应,高区域选择性地得到桉烷类倍半萜骨架中间体2c.     

Collective reaction behavior of an oscillating system coupled with an excitable reaction

The collective reaction behavior of limit cycles coupled to a nonoscillatory forcing is investigated experimentally and computationally. The coupled chemical system is constructed by adding 1,4-cyclohexanedione (CHD), a species which is capable of forming an oscillator with acidic bromate, into the cerium-catalyzed Belousov-Zhabotinsky reaction. Two levels of coupling exist in the system: (1) through autocatalytic reactions with bromine dioxide radicals and (2) via reactions with oxidized metal catalysts. Experiments illustrate that there is an optimum [1,4-CHD]/[cerium] ratio for inducing complex oscillations, whereas in the 1,4-CHD and malonic acid concentration phase plane two resonant ratios are observed for the onset of complex behavior. In addition, bromate, the oxidant for both suboscillators, also exhibits subtle influences on the complexity of the collective reaction behavior. The experimental observations are qualitatively reproduced with the Field-Koros-Noyes mechanism, modified to account for the coupling reactions with the 1,4-CHD-bromate system.     

Synthesis of 2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl Naphthalene: A Product from the Isomerisation of Diels-Alder Adducts of Both 5-Methyl- and 6-Methyl-2-acetyl-1,4-benzoquinone with 1,3-Butadiene

2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl-naphthalene was synthesised via Diels-Alder addition of 2-acetyl-3-methyl-1,4-benzoquinone to buta-1,3-diene followed by enolisation. It was identical with material obtained by pyridine-induced acetyl migration from the 1,3-butadiene adducts of both 3- and 6-methyl-2-acetyl-1,4-benzoquinone.     

Oxidative free radical reactions between 2-amino-1,4-benzoquinones and carbonyl compounds

The manganese(III) initiated oxidative free radical reactions of 2-amino-1,4-benzoquinone are described. The free radical reaction of 5,6-dimethyl-2-methylamino-1,4-benzoquinone (1) provides a novel method for the synthesis of indole-4,7-dione and indole-2,4,7-trione. High chemoselectivity was observed in different solvents. The regioselectivity of this reaction was also studied with 5-methyl-2-methylamino-1,4-benzoquinone (19). In most cases, indole-4,7-diones 20 and 21 were produced in high regioselectivity.     

A green approach for the electroorganic synthesis of 2-[(4-methyl-2-pyridyl)amino]-1,4-benzenediol derivatives in aqueous solution

The electrochemical synthesis of some new 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives was performed via the electrochemical oxidation of hydroquinones in the presence of 2-amino-4-methylpyridine in an aqueous solution. The results demonstrate that electrogenerated p-benzoquinone participated in the Michael-type addition reaction via an electrochemical–chemical (EC) reaction mechanism pathway and converted to the corresponding 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives. These new compounds have been synthesized in high yields and purity without using any toxic reagents or catalyst at the surface of carbon electrode.     

A novel oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles

The manganese(III) initiated oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles is described. This free radical reaction provides a novel method for the synthesis of spirodione 3 and spirolactone 4. With 5,6-dimethyl-2-methylamino-1,4-benzoquinone, spirodione 3 was obtained exclusively. On the contrary, with 5-methyl-2-methylamino-1,4-benzoquinone, spirolactone 4 was produced in high chemo- and regioselectivity. By heating with sodium acetate, spirodione 3 can be converted to 4 effectively.     

Aerobic oxidation of phenol to quinone with copper chloride as catalyst in ionic liquid

Aerobic oxidation of 2,3,6-trimethyl-phenol to trimethyl-1,4-benzoquinone with 2.5 mol% copper(II) chloride as catalyst in ionic liquid 1-n-butyl-3-methyl-imidazolium chloride, [BMIm]Cl, with n-butanol as co-solvent affording 86% yield provides a new alternative to the copper(II) chloride catalysed aerobic oxidation. The advantage of this catalytic system is that only a catalytic amount of copper(II) chloride is necessary. This catalytic system is also applicable for oxidation of 2-methyl-1-naphthol to 2-methyl-1,4-naphthoquinone. This catalytic reaction was systematically investigated under different conditions.     

Electrocatalytic influence of underpotential Tl,Pb and Bi monolayers on the electrochemical behaviour of rhodizonic acid and tetrahydroxy-1,4-benzoquinone on Pt in acid solutions

The electrochemical behaviour of rhodizonic acid and tetrahydroxy-1,4-benzoquinone on bare Pt and Pt surfaces covered by heavy metal monolayers deposited at underpotentials was studied in aqueous 0.5 M HClO₄ solutions. It was found that Tl, Pb and Bi monolayers catalyse markedly the oxidation of rhodizonic acid and tetrahydroxy-1,4-benzoquinone. The same underpotential layers improve the reversibility of the redox system tetrahydroxy-1,4-benzoquinone/hexahydroxybenzene. The enhancement of the overall oxidation and reduction processes has been interpreted in terms of the change of the reaction mechanism from an “inner sphere” mechanism on bare platinum to an “outer sphere” one of the Pt surfaces covered by underpotential layers. The two-electron oxidation of tetrahydroxy-1,4-benzoquinone to rhodizonic acid is followed by a rapid pseudo-first-order hydration reaction, the kinetics of which were studied by ring-disc experiments.     

Newbouldiaquinone and newbouldiamide: a new naphthoquinone-anthraquinone coupled pigment and a new ceramide from Newbouldia laevis

Newbouldiaquinone (1), a new naphthoquinone-anthraquinone coupled pigment and a new ceramide named newbouldiamide (2), have been isolated from Newbouldia laevis, besides the known compounds lapachol (3), canthic acid, oleanolic acid, 2-methyl-9,10-anthracenedione, 2-acetylfuro-1,4-naphthoquinone, 2,3-dimethoxy-1,4-benzoquinone, 2-(4-hydroxyphenyl)ethyl triacontanoate, beta-sitosterol and beta-sitosterol glucopyranoside. The structure elucidations of the isolated new compounds were performed on the basis of spectroscopic and chemical evidence. Preliminary studies showed that 1 is moderately antibacterial against Gram-positive Bacillus megaterium and that 3 has moderate herbicidal and antibacterial activities.     

2H-1,4-benzothiazines from the reaction of 2-aminoethanethiol with nascent 4-methyl-o-benzoquinone

4-Methyl-o-benzoquinone, generated oxidatively, reacts readily with 2-aminoethanethiol giving 5-hydroxy-7-methyl-1,3,4-dihydro-2H-1,4-benzothiazine (I) or 5-oxo-7-methyl-8-(2-hydroxy-4-methylphenoxy)-3,5-dihydro-2H-1,4-benzothiazine (VIII), depending on the conditions under which the reaction is performed. Chemical and spectral (uv, ir, nmr and ms) evidence for the assigned structures, as well as the course of the above mentioned reaction is described. A study of the behaviour of compound VIII in the presence of acids and alkalies is also reported.     

Reaction of thiosalicylic acid with 1,4-quinones and cyclization of the resulting arylsulfanylbenzoic acids

Thiosalicylic acid reacts with 1,4-benzoquinone to give 2-(1,4-dihydroxyphenylsulfanyl)benzoic acid which undergoes intramolecular cyclization to 1,4-dihydroxythioxanthen-9-one in the presence of dehydrating agents. Cyclization of arylsulfanylbenzoic acids obtained by reaction of thiosalicylic acid with 1,4-naphtho- and anthraquinones leads to 1,4-quinone derivatives, benzo- and naphthothioxanthenetriones.     

Eine einfache Synthese chiraler Arylbenzochinone und Arylbenzohydrochinone; Versucheines NMR.-Nachweises von Chiralität in isopropylsubstituierten Benzalanilinen

Atropisomeric diphenyls (V and VI) are easily prepared by the acid catalysed condensation of 2-methoxycarbonyl-1,4-benzoquinone and 2-acetyl-1,4-benzoquinone and trimethyl-1,4-benzoquinone respectively with 2-isopropyl-5-methylanisole and 2-isopropyl-3,5dimethylanisole. The reaction is not affected by steric hindrance; the more highly substituted phenols gave better yields. One of the diphenylderivatives has been resolved with help of dehydroabietylamine. Thermodynamic data for the racemisation process have been determined by classical polarimetric techniques (Table 4). The chirality of most of the compounds prepared is easily detected by considering the signals of the diastereotopic isopropyl group in the NMR.-spectrum. Probably because of solvent interaction NMR. kinetics have failed to give information about the racemisation process. Isopropyl-substituted benzal-anilines have been prepared. They did not show any ‘splitting’ of the isopropyl-groups in the NMR.     

Synthetic transformations of higher terpenoids: XXVIII. Diels-Alder reactions of 16-(trimethylsiloxybutadienyl) labdanoids

15,16-Epoxy-16-(3-trimethylsiloxybuta-1,3-dien-1-yl)labdanoids were synthesized, and their reactions with cyclic dienophiles (1,4-benzoquinone, 1,4-toluquinone, 2-bromo-6-methyl-1,4-benzoquinone, and N-methylmaleimide) were studied. The reactions with unsymmetrically substituted benzoquinones were not selective. Methods for the preparation of hybrid compounds containing furan diterpenoid and substituted naphthoquinone, octahydroisoindoletrione, or hexahydroisoindoledione fragments were proposed.     

醌型木素模型物的光学特性

为探索醌型木素化学结构与颜色的关系,以五种醌型木素模型物2-甲氧基-1,4-苯醌(I)、1,2-苯醌(II)、4-亚烯丙基-2-甲氧基-2,5-环己二烯酮(亚甲基醌)(III)、5-甲氧基-1,4-苯醌-2-氧负离子(IV)和5-甲基-1,4-苯醌-2-氧负离子(V)作为纸浆中醌型木素发色体的代表,在B3LYP/6-311++G(2d,p)水平上获得了它们在乙醇中的稳定基态构型,采用含时密度泛函理论(TD-DFT)在同等水平上计算了其在乙醇溶液中的电子光谱,并分析了它们在可见光范围内的吸收.结果发现:五种模型物在可见光范围内的吸收均源于电子的π→π*跃迁,它们的最大吸收波长顺序依次为IIIIIIIVV,吸光系数顺序依次为IVIVIIIII;漂白过程中生成的醌氧负离子以及邻醌类模型物具有中等大小的吸光系数(ε=1978-3197),吸收波长较长(445.47-552.36 nm),是漂白后纸浆具有颜色的重要原因.对醌类模型物吸收波长较小(414.91 nm),吸光系数大小为中等(ε=2094),亚甲基醌类模型物虽然吸光系数大(ε=31935),但吸收波长较小(407.90 nm),二者对漂白后纸浆的颜色影响较小.