羟基喹啉偶氮类化合物的互变异构与顺反异构的研究

本工作合成了数种带不同取代苯基的羟基喹啉偶氮类化合物。对它们在不同溶剂。不同酸碱度溶液中的偶氮式及腙式间互变异构平衡进行了研究。苯环上不同取代基的引入可引起平衡发生变化。拉电子基的引入有利于腙式结构的形成,而推电子基的引入则对偶氮的生成影响不大。此外,工作中还发现:羟基喹啉偶氮化合物在光照下存在着以偶氮顺-反异构化反应为主的变化过程。     

新型联苯胺替代偶氮化合物的合成及互变异构性质研究

以4,4’-二氨基苯甲酰替苯胺为重氮组分,以N-乙酰-L-酪氨酸为偶合组分,发生重氮化偶合反应,合成了一个新型的偶氮化合物,结构通过UV、1H NMR进行了表征。探讨了所合成化合物的偶氮式-醌腙式互变异构和顺反互变异构性质。结果表明,酸碱效应对偶氮-醌腙互变异构有着显著的影响。化合物在弱酸性条件下主要为醌腙体,中性条件下主要为偶氮体。在甲醇-水体系中,存在着一个pH依赖性的偶氮体-醌腙体分子离子平衡。偶氮化合物365 nm紫外光照射发生了反式-顺式光异构化过程,化合物可由稳定的反式结构变为顺式结构。     

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．     

偶氮染料的偶氮-醌腙互变异构的研究(Ⅰ) 1-苯基偶氮萘的偶氮-醌腙异构

本文合成了10个1-苯基偶氮萘染料,并测定了其~1H、~（13）C NMR（核磁共振）谱,对~1H谱进行了归属,确定了2种异构体的判据,讨论了萘环上取代基的电子效应和空间障碍、溶剂的极性和pH值对偶氮-醌腙互变异构的影响。     

偶氮染料的偶氮-醌腙互变异构的研究(Ⅰ) 1-苯基偶氮萘的偶氮-醌腙异构

本文合成了10个1-苯基偶氮萘染料,并测定了其~1H、~（13）C NMR（核磁共振）谱,对~1H谱进行了归属,确定了2种异构体的判据,讨论了萘环上取代基的电子效应和空间障碍、溶剂的极性和pH值对偶氮-醌腙互变异构的影响。     

论偶氮染料的偶氮-腙互变异构

偶氮染料存在着偶氮-腙互变异构。其中包括两个概念, 一是偶氮体和腙体是一对异构体, 由其结构不同导致其发色和化学性能不同;二是两种异构体在满足某种条件下可以互变。对偶氮体或腙体结构的识别是研究偶氮染料结构与性能的基础。当前染料学术界和产业界对偶氮-腙互变异构有两大误识:偶氮体即腙体, 两者不必加以区分;以及两者既为互变异构, 则时刻处于变化中而无法进行区分。本文针对上述误识, 讨论了两种异构体的结构与性能关系。一个偶氮染料的偶氮体及醌腙体是两种结构与性能, 如紫外-可见光谱吸收、化学反应性能及牢度不同的化合物。通常仅以某种异构体结构为稳定状态存在, 折中结构结决定了它的颜色和染色性能。两者仅在某种特定的条件下可以互相变化。这些条件取决于化合物结构、所处环境条件, 如温度、溶剂、介质pH等环境因素对偶氮-腙平衡的影响。介绍了用其红外光谱、拉曼光谱、核磁波谱、质谱以及晶体的X衍射谱来确认互变异构体的方法。     

偶氮羟基卟啉-噁二唑化合物的合成与光谱性能

合成了系列偶氮羟基卟啉-噁二唑化合物,通过1HNMR,FAB-MS,IR,UV-Vis确定了化合物的结构。核磁氢谱中远低场处(δ:13.0-16.0)醌腙体上亚胺基质子的出现及原料羟基卟啉羟基质子的消失表明,这些偶氮羟基卟啉-噁二唑化合物中存在着偶氮体和醌腙体的互变异构;红外光谱中1 725 cm-1附近CO强吸收的出现及3 400 cm-1附近的羟基伸缩振动峰的几乎消失表明,两种异构体中以醌腙异构占绝对优势。对合成化合物进行了光谱性能测定,实验结果表明,基态下,分子中噁二唑基团与卟啉基团相对独立,没有相互作用;而在激发态下,卟啉-噁二唑分子内存在着强烈的相互作用。该文报道了4种化合物的瞬态吸收光谱,为进一步研究卟啉-噁二唑分子激发态行为提供了参考。     

偶氮染料的偶氮-腙异构(一)

本文分三个部分综述了国内外近三十年来偶氮染料的偶氮-腙异构研究成果:(1)偶氮体或腙体结构的确认方法;(2)影响偶氮-腙平衡的结构因素和环境因素;(3)偶氮式或腙式结构与染料性能的关系。引用文献108篇。     

有机染料的互变异构(续完)

2.影响互变异构的环境因素如上所述,分子结构对互变异构平衡的影响很大,但环境的因素也有很大影响,例如(72),由于分子聚集的影响,溶液酸度的增加,由于亲核溶剂的应用,是以醌腙体型式存在,但是在气相中,亦即是排除了这些影响因素之后,它却是以偶氮体存在的。     

Solvatochromism,halochromism, and azo–hydrazone tautomerism in novel V‐shaped azo‐azine colorants – consolidated experimental and computational approach

The azo–hydrazone tautomerism, solvatochromism, and halochromism in four novel V‐shaped asymmetrical acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) compounds were examined. They contain 2,7,15,16‐functionalised benzophenazine cores connected to the anchoring electron‐deficient phenyl core via azo linkers and 2,7‐position fused with anthraquinone. These compounds derived from 2‐hydroxy‐1,4‐napthaquinone (lawsone) have been prepared in moderate to good yields. The synthesis involved the diazotisation of substituted aromatic amines, coupling onto 2‐hydroxy‐1,4‐napthaquinone, and further condensing the resulting azo compounds with 1,2‐diaminoanthraquinone in acetic acid. The absorption wavelengths of the dyes in different solvents were in the range 500–720 nm. The spectral changes of the synthesised azo‐azine compounds in different pH indicated the formation of hydrazone tautomer in acidic pH and of azo tautomer in alkaline pH. Density functional theory was used to assess the tautomers in terms of geometry and position of the tautomeric equilibrium. Time‐dependent density functional theory calculations allowed us to assign the electronic transitions (>90%) of the low‐energy bands.     

The mechanism and kinetics of the electrochemical cleavage of azo bond of 2-hydroxy-5-sulfophenyl-azo-benzoic acids

The electrochemical reduction of 2-hydroxy-5-[(4-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(3-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(2-sulfophenyl)azo]benzoic acid and 2-hydroxy-5-azo-benzoic acid has been carried out in aqueous solutions at glassy carbon electrode using cyclic voltammetry and chronoamperometry. The position of sulfo substituent relative to azo bridge as well as pH of the solution have significant impact on the electrochemical behavior of these compounds. It has been proposed that these compounds are reduced predominantly as hydrazone tautomers resulting in corresponding hydrazo compounds. The overall electrochemical reduction follows DISP2 mechanism, ultimately leading to the 5-amino salicylic acid and sulfanilic acid. The rate determining step is the homogenous redox reaction between intermediate hydrazo compound and 5-amino salicylic acid quinoneimine. The mechanism is proposed in which activated complex of 5-amino salicylic acid quinoneimine and intermediate hydrazo compound is formed with the simultaneous loss of one proton.     

以三氯化铁为新型氧化剂快速合成偶氮脲

在丙酮熔剂中,酸性介质条件下利用三氯化铁氧化二芳基取代氨基脲,快速制备新型偶氮化合物,反应条件温和,现象明显,产物容易分离,产率高。     

Synthesis and characterization of photopolymers with azo units. Interfacial polyaddition,photolysis, photodegradation

The synthesis of an aryl alkyl azo diisocyanate and a model azo urea is described. From the azo diisocyanate new azo polyureas were created by interfacial polyaddition. Molecular weights M_n in the range of 6000 to 9000 were determined by gel permeation chromatography (GPC). Photolysis and thermolysis of both, model compounds and polymers, were studied by UV-spectroscopy and differential scanning calorimetry (DSC), respectively, and the results were compared with those of similar azo amides. Photochemical polymer degradation was followed by GPC.     

Fe(III)/H2O2-Like System for Removal of Azo Dye from Aqueous Solution

Fe(III)/H₂O₂ system is an effective method for separating the organic compounds from aqueous solution, whereas it is often investigated under lower pH conditions. In order to improve performance of the system, a Fe(III)/H₂O₂-like system that was composed of iron-based coagulant and H₂O₂ was developed, which has the combined effect of flocculation and oxidation. The system when used for decolorization of an organic azo dye solution, Procion Red MX-5B, under wider pH range, indicated higher decolorization efficiency. Parameters affecting the decolorization such as coagulant dosage, H₂O₂ concentration, initial solution pH, temperature, and initial dye concentration were examined in this study. The results indicated that with appropriate coagulant dosage, H₂O₂ concentration, and pH, it was more effective for the decolorization, especially in a weak alkaline environment (pH = 7-8); the pseudo-first-order kinetics could express the azo dye concentration as a function of the reaction time. This study further illustrated that the azo dye solution was degraded to a degree with 53.22% TOC removal at an initial total TOC concentration of 14.92 mg/L. Overall, the established system in this study was favorable to the decolorization of soluble azo dye.     

三种偶氮化合物的合成及三阶非线性光学性能

文章选取具有非线性光学活性的偶氮化合物作为研究对象,合成了一组含不同取代基和不同推-拉电子结构的偶氮化合物,并通过红外光谱、紫外-可见吸收光谱、元素分析、核磁共振氢谱等方法对所合成的偶氮化合物结构进行了表征;用单光束Z-扫描的方法对所合成的偶氮化合物的三阶非线性光学性能进行了测试,并结合理论计算分析研究了分子结构对偶氮化合物三阶非线性光学性能的影响。     

Adsorption of reactive dyes from aqueous solutions by layered double hydroxides

BACKGROUND: Water‐soluble reactive azo dyes are the most problematic dye house effluents, as they tend to pass through conventional treatment systems unaffected. The release of these compounds into the environment is undesirable and their removal becomes environmentally important. In this work, synthesis, characterization and sorption properties of hydotalcite‐like compounds (Mg/Al and Mg/Fe), calcined and uncalcined, were investigated for the removal of the reactive azo dye Remazol Red 3BS. RESULTS: The calcined compounds present higher surface area than the uncalcined. The optimum pH for sorption was found to be 6. Thermodynamic analysis reveals that the sorption is spontaneous and endothermic. Equilibrium data were fitted by a Langmuir model, and kinetic data by a second‐order model. The calcined Mg/Al compound showed the highest sorption capacity, at 0.125 mmol g^?1. Regeneration of dye loaded derivative is achieved using the surfactant SDS. CONCLUSIONS: The prepared hydotalcite‐like compounds and especially calcined Mg‐Al exhibited significant adsorption capacity, kinetics, and regenerative ability. Its potential applicability as sorbent should be tested in a large‐scale implementation. Copyright © 2011 Society of Chemical Industry     

Liquid phase extraction of azo dyes by novel calixarenes bearing phthalonitrile and diiminoisoindoline groups

This paper presents a study on the removal of azo dyes [Methyl Orange (MO) and Trapaeolin 000 (TP)] from aqueous solution using new phthalonitrile and isoindoline substituted calix[n]arene derivatives into the organic phase in order to explore the potential use of these calixarenes as low-cost efficient extractants for removal of these azo dyes from wastewater. The effect of NaCl concentration, contact time, and pH on the extraction of these azo dyes was also investigated for all calixarene derivatives. The stoichiometric ratio between the calixarene derivatives (5 and 6) and selected azo dyes (MO and TP) was estimated through job’s plot.     

Immobilization horseradish peroxidase on amine-functionalized glycidyl methacrylate-<Emphasis Type="Italic">g</Emphasis>-poly(ethylene terephthalate) fibers for use in azo dye decolorization

Activated fibers were used as a new support material for the immobilization of horseradish peroxidase (HRP). Poly(ethylene terephthalate) (PET) fibers were grafted with glycidyl methacrylate (GMA) using benzoyl peroxide (Bz₂O₂) as initiator. 1,6-diaminohexane (HMDA) was then covalently attached to this GMA grafted PET fibers. HMDA-GMA-g-PET fibers were activated with glutaraldehyde and HRP was successfully immobilized. Both on the free HRP and the immobilized HRP activities, pH, temperature, thermal stability, and reusability were investigated. Both free enzyme and immobilized enzyme were used in a batch process for the degradation of azo dye. About 98% of azo dye removal was observed with immobilized HRP, while 79% of azo dye removal was found with the free HRP. 45 min of the contact time is sufficient for the maximum azo dye removal. The HRP immobilized on modified PET fibers were very effective for removal of azo dye from aqueous solutions.     

Polarographic behaviour of aliphatic azoxy compounds

Both isomeric cis and trans forms of aliphatic azoxy compounds are reduced in the same way in acid and neutral media: they are adsorbed, protonated, then reduced in one 4 electron step to give hydrazo compounds. The intermediate azo isomer is more easily reducible than the depolariser.In basic medium, the azoxy derivatives may be divided into two groups, depending on the ability of the neutral molecule to be reduced or not. When the neutral azoxy compound is reduced, the hydrazo compound is usually the final product of the reduction if the neutral form of the azo compound is also reducible. For cis azoxycyclohexane, trans azo and hydrazo are generated. This result suggests a new reduction path for neutral azoxy compounds. A mechanism is postulated, leading to an intermediate unstable N-hydroxyhydrazine which dehydrates very fast into cis and trans azo compounds.