Photochromism of the azo tautomer of 4-phenyiazo-1-naphthol and its o-methyl ether in solvents and polymer substrates

The trons ? cis photoisomerism of 1-phenylazo-4-methoxynaphthalene and the azo tautomer of 4-phenylazo-l-naphthol was studied in liquid solvents (ethanol and cyclohexane) and polymer films (cellulose acetate and triacetate, and poly(methyl methacrylate)). In the solvents, first-order kinetics for thermal cis → trans reversion of the former compound were observed after overlap of the absorbance bands of each isomer had been taken into account. However, in polymer substrates, the heterogeneous environment and restricted molecular motion gave rise to more complicated kinetics. The cis isomer of the azo tautomer of 1-phenylazo-4-naphthol had too short a lifetime to be observed in solution, but in dry polymer substrates its lifetime was sufficiently prolonged to allow spectroscopic observation. Wetting the dyed polymer films with water greatly accelerated the rate of cis → trans reversion of the azo tautomer of 1-phenylazo-4-naphthol.     

偶氮染料的偶氮-醌腙互变异构的研究(Ⅱ)──2-苯基偶氮-1-萘酚的偶氮-醌腙异构

合成并测定11个2-苯基偶氮-l-萘酚染料的~1H、~13CNMR谱，对氢谱进行了归属，讨论了苯环上取代基的电子效应、溶剂的pH值对偶氮-醌腙互变异构以及结构对颜色的影响．     

偶氮染料的偶氮-醌腙互变异构的研究(Ⅱ)──2-苯基偶氮-1-萘酚的偶氮-醌腙异构

合成并测定11个2-苯基偶氮-l-萘酚染料的~1H、~13CNMR谱,对氢谱进行了归属,讨论了苯环上取代基的电子效应、溶剂的pH值对偶氮-醌腙互变异构以及结构对颜色的影响．     

The role of azo-hydrazone tautomerism in the photofading of 1-phenylazo-4-naphthol in polymer substrates

The photofading of 1-phenylazo-4-naphthol has been studied in films of cellulose acetate and cellulose triacetate. The relative rates of fading of the azo and hydrazone tautomers were monitored by resolving the visible absorbance spectrum of the dye into two overlapping bands corresponding to each tautomer. Permanent photofading of 1-phenylazo-4-naphthol was found to be due to oxidative attack on the ground state hydrazone tautomer of the dye by singlet excited oxygen. The lowest excited triplet state of the hydrazone tautomer was responsible for sensitizing singlet oxygen. The azo tautomer was resistant to permanent photofading, but its concentration was depleted during irradiation while it temporarily existed in the hydrazone form. As well as thermal tautomeric interchange, tautomeric conversion following trans → cis isomerization of the azo tautomer could have been responsible for this temporary existence. Relative fading rates were influenced by the nature of the polymer concerned, and the method used to incorporate the dye. Temporary fading occurred as a result of isomeric and conformational changes in each tautomer.     

The effect of polycation on the light fastness of CI Acid Red 249

Cationic compounds are frequently used in direct dyeing processes and in ink-jet printing as dyefixing agents. In some cases, however, they can reduce the light fastness of dyes used. This report deals with the effect of a polycationic compound, Polyfix 601, on the light fastness of CI Acid Red 249, an anionic 2-phenylazo-1-naphthol dye, in aqueous solutions and in PVA films. As a comparison, the much smaller ammonium cation was used, which had no observable effect on hue or dye light fastness. However, some changes to the dye's physical properties were observed. The effect of the polycation is explained as a consequence of dye aggregation, facilitated by presence of polycation. Self-sensitised singlet oxygen seemed to play no part in dye photofading, but other oxygen species could participate in the process.     

Ab initio modeling of the solvent influence on the azo-hydrazone tautomerism

The solvent effect on the azo (A) -hydrazone (H) tautomeric equilibrium of 1-phenylazo-4-naphthol is modeled by using ab initio quantum-chemical calculations. It was found that in methanol, methylene chloride and water there exists a strong hydrogen bonding between the particular tautomer and solvent, as well as dipole–dipole dye-solvent interactions. The results show that the H-form is more stable in water and methylene chloride, while methanol and i-octane stabilize the A-form. The calculational results obtained are in very good agreement with the experimental data in these solvents published previously.     

Synthesis of disazo dyes derived from heterocyclic components

In this study, 2-phenylhydrazone-3-ketiminobutyronitrile was synthesised and reacted with hydrazine hydrate and phenylhydrazine to afford the corresponding 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole, respectively. Ten novel disazo dyes were then synthesised by diazotisation of 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole using nitrosylsulphuric acid, and coupling with 4-hydroxy-6-methyl-2-pyrone, 4-hydroxycoumarin, 3-methyl-1H-pyrazolin-5-one, 3-methyl-1-phenylpyrazolin-5-one and 3-cyano-6-hydroxy-4-methyl-2-pyridone. The dyes were characterised by elemental analysis and spectral methods. The solvatochromic behaviour of these disazo dyes in various solvents was evaluated. Received: 18 May 2005; Accepted: 8 July 2005.     

Products of Ozonolysis of Aromatic Compounds in Aqueous Solution Containing Nitrite Ion

Aqueous solutions of 4-chlorophenol, 2,4-dichlorophenol, methoxybenzene, 1-naphthol, and naphthalene at a concentration of 0.5-1 × 10^?4 M reacted with two equivalents of ozone at pH 7.25-10.65 to form various oxidation products. When the reactions were conducted in the presence of nitrite ion (0.5-1.0 × 10^?4 M), a nitration reaction occurred with three of the five aromatic compounds (4-chlorophenol, 2,4-dichlorophenol, and 1-naphthol). Aromatic compounds that undergo nitration under the conditions of the experiments have a higher reaction rate than that for the reaction of ozone and nitrite ion.     

Iron(III)-induced activation of hydrogen peroxide for oxidation of 2-methylnaphthalene in glacial acetic acid

Simple iron(III) salts activate hydrogen peroxide to oxidize 2-methylnaphthalene to 2-methyl-1-naphthol in glacial acetic acid. 2-Methyl-1-naphthol is then oxidized to 2-methyl-1,4-naphthoquinone by hydrogen peroxide without influence of the catalyst. This is in contrast to the previous reports, which excluded the formation of 2-methyl-1-naphthol as an intermediate product in the process of 2-methylnaphthalene oxidation to 2-methyl-1,4-naphthoquinone. The process, however, mimics the microbial conversion of 2-methylnaphthalene to 2-methyl-1,4-naphthoquinone. The presence of chloride in the system causes exclusively the formation of 2-methyl-1-chloronaphthalene.     

球磨机中无溶剂高效合成1,1’-联二萘酚

球磨机中机械力化学作用下,β-萘酚经CuCl2·2H2O氧化偶联,无溶剂固态直接合成1,1’-联二萘酚,产率达91%。最佳反应条件为:球磨机转速350 r/min,n(CuCl2·2H2O)∶n(β-萘酚)=2∶1,研磨时间2 h。同时考察了其他Cu(Ⅱ)/Fe(Ⅲ)的金属盐氧化剂作用的β-萘酚的氧化偶联。     

Poly (acridine orange) film modified electrode for the determination 1-naphthol in the presence of 2-naphthol

The voltammetric behavior of 1-naphthol was studied with a poly (acridine orange) (PAO) film modified glass carbon electrode (GCE). The electrooxidation of 1-naphthol was an irreversible process with its oxidation overpotential at the PAO electrode 180 mV lower than that on the GCE. PAO electrode demonstrated electrocatalytic activity to the electrooxidation of 1-naphthol giving a greatly improved detection limit down to 8 × 10⁻⁸ mol L⁻¹(S/N = 3). At the optimal experimental condition, the oxidation peak current from the PAO electrode was linearly proportional to the concentration of 1-naphthol in the range of 2 × 10⁻⁷ to 3.2 × 10⁻⁶ mol L⁻¹ and 5.2 × 10⁻⁶ to 1.2 × 10⁻⁴ mol L⁻¹. The differences of the oxidation peak potentials between 1-naphthol and the coexisted 2-naphthol was 170 mV allowing the selective detection of 1-naphthol in a mixed solution with 2-naphthol. The detection of 1-naphthol in tap water and river water was carried out with satisfactory results.     

Adsorption of phenol and 1-naphthol onto XC-72 carbon

XC-72 carbon (XC-72) was characterized by SEM, XPS, N₂ adsorption-desorption, particle size distribution analysis and potentiometric acid-base titration. The adsorption of phenol and 1-naphthol on XC-72 was studied as a function of contact time, pH, adsorbent content and temperature. The kinetic adsorption data were described well by the pseudo-second-order model. The adsorption isotherms of phenol were described well by Freundlich model, while the adsorption isotherms of 1-naphthol were fitted well by Langmuir model. The results demonstrated that XC-72 had much higher adsorption capacity for 1-naphthol than for phenol. The adsorption thermodynamic data were calculated from the temperature-dependent adsorption isotherms at T=293, 313 and 333 K, and the results indicated that the adsorption of phenol was an exothermic process, whereas the adsorption of 1-naphthol was an endothermic process. XC-72 is a suitable material for the preconcentration of phenol and 1-naphthol from large volumes of aqueous solutions.     

1，1′-硫代双（2－萘酚）的合成

以2-萘酚为主要原料,与二氯化硫在甲苯、乙酸乙酯组成的混合溶剂中反应,合成了抗氧剂1,1′-硫代双（2-萘酚）。确定的最佳反应条件为：溶剂为由甲苯、乙酸乙酯组成的混合溶剂,甲苯、乙酸乙酯重量比为3：2,溶剂与2－萘酚重量比为8：1,2－萘酚与二氯化硫物质的量比为2：1．03,反应温度10-20℃,反应时间3h,产品收率84．7％,纯度大于99．0％。     

The photochemistry of 1-benzoyl-2-naphthol and 6-hydroxybenzanthrone and their effect on the rate of photo-oxidation of polypropylene

A comparison of the effect of two structurally similar additives, 1-benzoyl-2-naphthol and 6-hydroxybenzanthrone, on the rate of photo-oxidation of polypropylene under conditions of simulated daylight shows that while 6-hydroxybenzanthrone acts as a prodegradant, 1-benzoyl-2-naphthol is a light stabilizer. Examination of the spectroscopic and photochemical properties of 1-benzoyl-2-naphthol indicates that in fluid solution the photoexcited stabilizer is probably deactivated within the singlet manifold. In glassy solvents at 77°K, on the other hand, triplet formation does occur, but only in molecules in which the intermolecular hydrogen bond of the 1-benzoyl-2-naphthol is disrupted.     

Methylation of 2-naphthol over molecular sieves

The mesoporous molecular sieves of the type MCM-41 with different pore openings (40, 64 and 80 Å) were used as catalysts in the gas-phase methylation of 2-naphthol by methanol at 473 K. Their catalytic activity was compared with that of BEA, SAPO-5 and SAPO-11. The molar ratio of 2-naphthol : methanol was varied from 1 : 4 to 1 : 6. The alkylation of the hydroxyl group (O-alkylation) as well as of the aromatic ring (C-alkylation) proceeded. The best yield of 2-methoxynaphthalene was achieved using MCM-41 40 Å and molar ratio 2-naphthol : methanol = 1 : 6.     

微波辐射下1,3-二硝基-2-萘酚的合成

微波辐射下,2-萘酚与硝酸铈铵在醋酸和聚乙二醇溶液中反应生成1,3-二硝基-2-萘酚。提供了一种温和的、简便的制备1,3-二硝基-2-萘酚的一种新方法。结果表明最佳反应条件为:2-萘酚与硝酸铈铵的物质的量比为1∶1.2,辐射功率:30 W:辐射爬升时间:4.00 min;微波反应时间:4.00 min;温度:45℃(最大54℃);压力:207 kPa;1,3-二硝基-2萘酚的产率达76.4%。     

无溶剂CTAB催化制备取代2-氨基-2-色烯

在溴化十六烷基三甲基铵(CTAB)催化及无溶剂条件下,由芳亚甲基丙二腈与1-萘酚或2-萘酚发生加成、环化反应,生成相应的取代2-氨基-2-色烯。     

无溶剂碱催化制备取代2-氨基-2-色烯

在氢氧化钠催化及无溶剂条件下,由芳亚甲基丙二腈与1-萘酚或2-萘酚发生加成、环化反应生成相应的取代2-氨基-2-色烯。     

1-氨基-2-萘酚-4-磺酸的合成工艺研究

以 β 萘酚为原料 ,在水 醇混合溶剂存在下 ,经亚硝化、加成、磺化制得 1 氨基 2 萘酚 4 磺酸 ,考察了原料配比、混合溶剂配比、反应时间、反应温度及过滤等因素对反应的影响 ,确定了优惠工艺条件。亚硝化条件 :n(酚 )∶n(亚硝酸钠 )∶n(硫酸 ) =1∶1∶0 5 ,以 10 gβ 萘酚计 ,有机溶剂异丙醇用量 15ml,混合溶剂配比V(水 )∶V(异丙醇 ) =(1～ 1 5 )∶1。亚硝化完毕后将物料过滤 ,水洗。加成反应时间控制在 6h ,n(酚 )∶n(亚硫酸氢钠 ) =1∶2 ,碘化反应时间6h ,温度 5 0～ 6 0℃。在此条件下 ,收率达到 72 1%。