用循环伏安法研究醌亚胺的脱氨反应

用循环伏安法研究了N,N-二乙基对苯二胺,N,N,N′,N′-四乙基对苯二胺,N,N-二乙基氨基酚三类化合物的电化学氧化及其氧化产物的后继化学反应,求算了脱氨反应速率常数,揭示了苯环上甲基取代基和氮原子上不同取代基对脱氨反应的影响。 脱氨反应为OH~-或水进攻醌亚胺的亲核反应。由于甲基的斥电子效应,当苯环上引进甲基取代基时,环上负电荷增大,带正电荷的醌亚胺趋于稳定,水解反应速度减慢。 苯环上引进二个甲基取代基,其相应的苯胺化合物的半波电位下降大约120mV。二乙基对苯二胺的苯环上每引进一个甲基取代基,其氧化产物与彩色成色剂偶合生成的染料的吸收峰向长波方向移动20—30nm。     

电合成芳香醛反应机理的研究

利用红外光谱（IR）研究了槽外合成对甲氧基苯甲醛和对溴苯甲醛的反应机理，结果证明：在Ce^4＋与对取代甲苯的氧化反应中，苯环上甲基被Ce^4＋氧化的难易受苯环上对位取代基的影响。对甲基苯甲醚先氧化成对甲氧基苯甲醇，再氧化成对甲氧基苯甲醛并最终氧化成对甲氧基苯甲酸，第一个电子传递步骤为控制步骤：对溴甲苯先氧化成对溴苯甲醇，再氧化成对溴苯甲醛，后者为控制步骤。     

聚苯醚苯环上甲基的卤化反应,成季铵盐反应及磷化反应的研究进展

本文综述了酚类氧化偶联反应，聚苯醚苯环上甲基的卤化反应，成委铵盐反应及磷化反应的研究进展。为开发新型的表面活性剂，离子交换树脂具有指导意义。     

不同金属氧化物阳极上甲基橙的电化学氧化降解

分别以Ti/SnO2+Sb2O3和Ti/SnO2+Sb2O3/PbO2电极为阳极进行甲基橙的电化学氧化,研究了两种金属氧化物阳极上甲基橙氧化降解过程的反应速率、电流效率及COD的变化.结果表明,两种金属氧化物阳极都能有效氧化降解甲基橙,氧化反应符合一级反应动力学规律,在Ti/SnO2+Sb2O3和Ti/SnO2+Sb2O3/PbO2电极上甲基橙氧化降解过程的表观速率常数分别为0.148和2.43×10-2 min-1. 以Ti/SnO2+Sb2O3为阳极电解30 min,甲基橙的浓度从初始时的0.305 mmol/L降至4.89×10-3 mmol/L,甲基橙的转化率达98.4%;在Ti/SnO2+Sb2O3/PbO2电极上,相同电解时间下甲基橙的浓度只降至0.14 mmol/L,转化率为55.0%. 对不同电极上甲基橙电化学氧化过程电流效率的研究表明,Ti/SnO2+Sb2O3电极的电流效率明显高于Ti/SnO2+Sb2O3/PbO2电极. Ti/SnO2+Sb2O3电极的反应速率大、电流效率高主要源于其较高的析氧电位.     

六次甲基四胺对AZ91D镁合金阳极氧化的影响

向主要成分为氢氧化钠、硅酸钠与对苯二甲酸的基础电解液中添加六次甲基四胺(HMTA),在AZ91D镁合金表面制备阳极氧化膜。采用扫描电镜(SEM)、光学显微镜、X射线衍射仪(XRD)及极化曲线测量,分析了六次甲基四胺对镁合金阳极氧化过程以及阳极氧化膜的形貌、相组成和耐腐蚀性能的影响。结果表明:在镁合金恒电流阳极氧化过程中,六次甲基四胺能够提升氧化电压,抑制弧光放电,令膜层中SiO-₂相增多,膜层微孔数减少,致密度和厚度都得到提升,进而提高膜层的耐腐蚀性能。     

连四甲苯液相氧化过程热力学分析及动力学模拟

连四甲苯（PR）液相氧化制备苯偏四甲酸（MPA）是合成聚偏苯四甲酰亚胺单体的关键步骤。本文首先采用基团贡献法对MPA的热力学参数进行了估算,进一步分析了PR氧化过程热力学参数随温度的变化。结果表明,在研究温度范围内,该氧化过程为强放热反应,反应过程中需要及时移除反应热以控制温度的波动。通过间歇实验研究了不同催化剂浓度和温度对反应的影响,动力学实验结果表明,保持催化剂总浓度不变,改变催化剂配比对PR氧化速率影响不大,但是提高Mn浓度对MPA生成速率的提升效果最佳;升高温度能够明显提升目标产物MPA的选择性。基于自由基链式反应机理,建立了简化的PR氧化集总动力学模型,拟合回归得到苯环上首个甲基氧化的活化能为57.20 kJ·mol^-1;但是苯环上部分甲基被氧化为羧基后,其他甲基氧化的活化能增加为120.30 kJ·mol^-1,说明羧基的存在使甲基活性变弱,被进一步氧化的难度增加。论文相关研究成果可为MPA生产新工艺的开发和工业反应器设计提供参考依据。     

3-甲基吡啶在Pb-PTFE修饰电极上的电氧化行为

采用复合电镀法制得Pb-PTFE疏水性修饰电极,并作为阳极应用于3-甲基吡啶水溶液的电氧化。结果表明,3-甲基吡啶在Pb-PTFE疏水性修饰电极上呈现明显的电氧化行为。根据电氧化产物的FT-IR谱图推测3-甲基吡啶在Pb-PTFE修饰电极上可能被电氧化为烟酸。电化学交流阻抗测试表明3-甲基吡啶在Pb-PTFE修饰电极上的电氧化动力学过程主要受电荷迁移和浓差扩散混合控制,可用R(Q(CW))等效电路进行模拟。     

钛基TiO_2纳米管光电催化降解甲基橙

采用阳极氧化法制备了TiO2纳米管,并进行扫描电镜分析。以TiO2纳米管为工作电极,石墨作对电极,对甲基橙溶液进行光电催化降解研究,考察了阳极氧化电压、时间、热处理温度、电解液组成、外加偏压的影响。结果表明,阳极氧化电压为20 V,氧化时间20 min,热处理温度500℃,V(H3PO4)∶V(NH4F)=1∶1,外加偏压为0.6 V时,甲基橙(5 mg/L)经TiO2纳米管光电催化30 min,脱色率达到96.3%。     

钛基TiO_2纳米管光电催化降解甲基橙

采用阳极氧化法制备了TiO2纳米管,并进行扫描电镜分析。以TiO2纳米管为工作电极,石墨作对电极,对甲基橙溶液进行光电催化降解研究,考察了阳极氧化电压、时间、热处理温度、电解液组成、外加偏压的影响。结果表明,阳极氧化电压为20 V,氧化时间20 min,热处理温度500℃,V(H3PO4)∶V(NH4F)=1∶1,外加偏压为0.6 V时,甲基橙(5 mg/L)经TiO2纳米管光电催化30 min,脱色率达到96.3%。     

对甲基苯磺酸在Ti/PbO2电极上的电氧化反应信息

采用原位红外光谱法系统地研究了对甲基苯磺酸（p-TSA）在钛基二氧化铅（Ti/PbO₂）电极上的电氧化反应信息。循环伏安曲线显示,Ti/PbO₂对p-TSA有良好的电氧化活性,直接氧化电位区间为0.55~0.9 V。多步电位阶跃FTIRS（MSFTIRS）和时间分辨FTIRS（TRFTIRS）分析显示,电压小于1000 mV时,p-TSA主要发生了磺酸基的脱落和苯环侧链甲基的氧化;电压大于1000 mV时,p-TSA的苯环骨架被破坏,同时生成了酸、醇、酮。反应动力学研究结果表明,p-TSA电氧化表观速率常数K与电流密度j呈线性关系,化学需氧量（COD）去除量随比电荷增大而增加,平均电流效率则呈下降趋势。     

Electrochemical generation of triplet states VI—1. A mechanistic study of the luminescence processes at the anodic cleavage of 2,2′- and 4,4′-bipyranes in presence of aromatic hydrocarbons

During the anodic oxidation of mixtures of a fluorescent aromatic hydrocarbon and a 2,2′- or a 4,4′-bipyrane in acetonitrile/benzene the emission of the hydrocarbon is observed. it results from a systematic study using rotating disk and ring-disk electrode techniques that this luminescence is caused by the electron transfer between the pyranyl radicals generated in the anodic cleavage of the bipyrane and the hydrocarbon cation radicals. Measurements in a magnetic field and thermodynamical considerations prove a triplet ECL mechanism. As visible from the ECL intensity—potential curves the pyranyl radicals are generated by two different mechanisms. The heterogeneous one electron oxidation of the bipyrane and the following cleavage of a single bond is replaced with the indirect anodic oxidation by means of the reversible hydrocarbon redox system at more positive potentials.     

Electrochemical properties of quaternary ammonium borodiglycolates and borodioxalates

Quaternary ammonium borodiglycolates and borodioxalates were prepared by the reaction of quaternary ammonium tetrahydroxyborates with glycolic acid and oxalic acid, respectively. These compounds are used as the electrolyte salts of aluminum electrolytic capacitors. Their molar conductivities, limiting molar conductivities and oxidation potentials in γ-butyrolactone were higher than those of borodisalicylates and borodicatecholates due to the lack of aromatic rings. Their film-forming ability of anodic aluminum oxide in γ-butyrolactone electrolytes containing a small amount of water was poor, because both anodic dissolution and oxidation occurred simultaneously.     

Electrochemical and UV–Vis/ESR spectroelectrochemical properties of thienylenevinylenes substituted by a 4-cyanostyryl group

The π-electron delocalisation in conjugated thienylenevinylenes bearing arylethenyl chromophores, makes those materials interesting candidates for electro-optic applications. In this study, we report the results of electrochemical and UV–Vis/ESR spectroelectrochemical studies of a pair of thienylenevinylenes substituted by the 4-cyanostyryl group, bearing either a hydrogen, or methyl group terminated α carbons at the peripheral thiophene rings. The reactivity of various functional segments of investigated molecules was assessed by comparing the reactivity of the protected and unprotected counterparts and the behaviour of their electrooxidation products. For the capped derivative, two irreversible anodic redox processes giving electrochemically inactive products were observed, while the uncapped molecule yields electroactive materials already upon its first oxidation step.     

Mild oxidations of coal models

Relative rates of oxidation of numerous coal models have been determined by two methods in radicalinitiated oxidations at 50 °C. The results show that hydroaromatic rings (as in 9,10-dihydroanthracene and tetralin) and some anthracenes are so much more reactive than CH₂O or CH₂ links between benzene rings that cleavage reactions of the latter groups would be excluded in competitive oxidation. However, similar connecting links between naphthalene or more condensed rings will be more competitive. Rates of oxidation of condensed aromatic hydrocarbons can now be related to extensive previous data on alkylbenzenes and a variety of aliphatic compounds.     

Studies on electrosynthesis of organic compounds. I. Electrolytic esterification in aqueous solutions

The anodic oxidation of methyl alcohol in the presence of different carboxylic acids was found to give the methyl ester of these acids as the main product. Neither Kolbe products nor formaldehyde were formed. These results are interpreted in terms of a free radical mechanism which involves attack of the carboxylic acids by methoxyl radicals to give the ester.     

Synthesis of new tripodal ligand: N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]benzylamine.: Catecholase activity of two series of tripodal ligands with some copper (II) salts

A synthesis of new tripodal ligand: N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]benzylamine is reported. Copper (II) complexes of compounds: N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-amines (L1–L5) and N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]-amines (L6–L9) were examined for their catalytic activities. The dioxygen complexes of copper (II) were generated in situ by stirring copper salts and the tridentate pyrazole ligands. It has been found that the oxidation of 3,5-di-tert-butylcatechol is very efficient to give 3,5-di-tert-butylquinone. Ligand structure has proven critical in controlling not only the formation of complexes but also their subsequent reactivity. The nature of junction between the pyrazolic rings and the benzene have a large effect on the oxidation reaction rate.     

ESR-Spektroskopischer nachweis von radikalkationen bei der anodischen oxidation von alkylbenzolen in methylenchlorid und trifluoressigsäure

The anodic oxidation of hexaethyl- (HEB), hexa-methyl- (HMB), pentamethyl- (PMB) and 1,2,4,5-tetramethyl-benzene (TMB) on Pt in CH₂Cl₂ and CF₃COOH (TFA) is examined by cyclic voltammetry and esr spectroscopy. HEB, HMB and PMB are oxidized to the corresponding radical cations in TFA. The anodic oxidation of HMB and PMB in CH₂Cl₂ results in radical cations with one methyl group more than the starting material. The mechanism of the formation of these radical cations is discussed for HMB.     

Initial reaction steps in photocatalytic oxidation of aromatics

Transient reaction at 273 and 300 K was used to study the initial steps in the photocatalytic oxidation (PCO) of benzene, toluene, p-xylene, mesitylene, benzyl alcohol, benzaldehyde, and m-cresol adsorbed on a thin film of TiO₂ catalyst. Adsorbed aromatics were oxidized by O₂ photocatalytically in the absence of gas-phase aromatics, and the compounds remaining on the surface were characterized by temperature-programmed oxidation and desorption (TPO, TPD). Benzene and methyl benzenes oxidize rapidly at 273 or 300 K to form adsorbed intermediates that are more strongly adsorbed and much less reactive than the original aromatic, which is relatively weakly adsorbed on TiO₂. The catalyst is expected to be covered with these intermediates during steady-state reaction. The rates of PCO of benzene and methyl benzenes to CO₂ are slow relative to complete oxidation of alcohols or chlorinated hydrocarbons. The intermediates do not appear to be alcohols or aldehydes formed by oxidation of a methyl group, nor do they correspond to addition of an hydroxyl to the aromatic ring. Benzyl alcohol oxidizes photocatalytically to benzaldehyde and then to CO₂ and H₂O during PCO, but adsorbed m-cresol does not photocatalytically oxidize.     

保留取代基团的苯环选择加氢反应催化剂研究进展

具有复杂取代基团苯基衍生物的苯环选择加氢属于原子经济反应，不仅可以消除苯环对人体健康的潜在危害，而且能够赋予所合成材料以特殊功能。本文综述了保留取代基团苯环选择加氢反应的催化剂、操作条件及反应性能的研究进展，主要包括芳香二胺、芳香酯类、芳香族氨基甲酸甲酯、聚苯乙烯、联苯及双酚A等的苯环催化加氢反应。为了使苯环上取代基团不发生反应，多采用Rh、Ru、Pd和Pt等贵金属催化剂。Ni等非贵金属催化剂的活性和选择性有待进一步提高。因此，今后研究重点应是开发减量或替代贵金属的高性能催化剂。     

Influence of the alignment degree of CVD-grown carbon nanotubes on their functionalization and adsorption capacity

Oxygen functionalized multiwalled carbon nanotubes (CNTs) were prepared from aligned and bundle-like CVD-grown CNTs by chemical treatment with different reagents of increased oxidation degree. As the severity in the oxidation degree increases elimination of the amorphous carbon is observed. However, contrary to what was previously reported, aligned CNTs treated in less severe oxidation conditions they exhibit an increased number of oxygen containing functional groups (COH/CO groups). Meanwhile, when treated in the more severe oxidation conditions, they have the highest number of COOH groups due to the appearance of defects and shortening of the tubes. In the benzene adsorption in water, aligned CNTs display faster kinetics in all cases. The best adsorption capacity is achieved with aligned CNTs treated in very severe conditions possibly due to their enhanced solubility in water, which favors electrostatic interactions and π–π interactions between the benzene rings and the CNT walls.