【作者】 陆婷婷；

【导师】 陆明；

【作者基本信息】 南京理工大学 ， 应用化学， 2013， 博士

【摘要】 芳烃侧链的氧化反应主要是有机合成反应中重要的反应类型,其产物在化学工业的各个分支都有广泛的应用。早期的芳烃氧化是使用高锰酸钾等计量氧化剂,这些氧化剂氧化能力较强,选择性却较差。近些年,由于绿色氧化技术的发展,使用绿色方法高效的氧化芳烃已经成为研究热点。本课题主要研究了硝基芳烃的绿色氧化偶联反应,硝基联苄的氧化脱氢反应,和绿色氧化剂在离子液体介质中,自由基催化选择性需氧氧化芳烃到相应酸。具体研究包括以下几个方面。使用次氯酸钠溶液氧化2,4,6-三硝基甲苯(TNT)生成产物2,2’,4,4’,6,6’-六硝基联苄(HNBB)和2,4,6-三硝基苄氯(TNBCl),其中HNBB和TNBCl的产率均高于80%。讨论了反应溶剂,次氯酸钠的pH值和有效氯含量对反应的影响,其中对于HNBB,溶剂乙酸乙酯代替了THF。探索了反应机理,并着重分析了溶剂中醇的作用：通过醇,碱与TNT反应生成了中间体三硝基苄基阴离子,从而进一步生成产物HNBB和TNBCl。使用两种自由基催化剂2,2,6,6-四甲基哌啶-N-氧自由基(TEMPO)和N-羟基苯邻二甲酰亚胺(NHPI),分别与金属盐氯化亚铁(FeCl2)催化HNBB脱氢制备2,2’,4,4’,6,6’-六硝基茋(HNS),其中TEMPO和NHPI催化生成HNS的产率为80%和70%。使用了绿色氧化剂氧气代替传统液溴,溶剂二甲亚砜代替有毒溶剂吡啶。研究了TEMPO和NHPI催化的脱氢机理,并将催化体系TEMPO/FeCl2用于其它硝基联苄的需氧脱氢反应。计算了HNBB的C-H和C-N键解离能,对比了TEMPO和NHPI的催化活性,说明了与传统方法相比,新方法存在的优势。在温控两相聚乙二醇酸性离子液体(PEG1000-DAIL)介质中,两种自由基催化剂NHPI和THICA与乙酸钴共同催化芳烃需氧氧化到相应酸。一系列的芳烃均高效的氧化成相应产物,对于NHPI而言,目标底物甲苯的转化率达到99%,产物苯甲酸的选择性为99.5%,且二甲苯被氧化成相应的甲基苯甲酸。而对THICA而言,甲苯的转化率为100%,苯甲酸的选择性为99.7%。二甲苯被氧化成相应的二酸,硝基芳烃亦可被氧化到酸。反应条件温和,操作简单,产物的提取方法容易。反应首次回收了溶剂和催化剂,并在循环使用八次后,反应的转化率无明显的下降。尝试将自由基NHPI的助催化剂丁二酮肟(DMG)和二氧化锰(Mn02),与自由基THICA共同催化烷基苯需氧氧化反应。一系列含有供电子或吸电子取代基的烷基苯在温和条件下选择性氧化成相应酸。其中DMG和Mn02催化目标底物甲苯的氧化转化率分别为99.0%和98.8%,产物苯甲酸的选择性均达到99.0%。反应溶剂和催化体系可以方便的回收循环使用,其中循环八次后催化活性基本保持不变。讨论反应时间和温度,反应溶剂,THICA助催化剂,催化剂加入量对反应的影响。研究了THICA的催化机理,通过实验探索,证明了DMG和MnO2均可提取THICA的H原子,使其生成相应的自由基,从而进一步氧化烷基苯。更多还原

【Abstract】 The oxidation of alkylaromatics is of major industrial importance, and improving its efficiency and selectivity for the value-added products remains a challenge. Traditional approaches for the reaction were based on stoichiometric reagents (potassium hypermanganate) oxdiation, but the disadvantages of low products selectivity could not be avoided. In recent years, green oxidation of alkylaromatics is attracting continuous attention due to the development of oxidation technology.The research mainly concentrates on the oxidative coupling of nitrotoluenes, the oxidative dehydrogenation of nitro derivatives of bibenzyl and the aerobic selective oxidation of alkylaromatics to acids in ionic liquid.Trinitrotoluene (TNT) is oxidized to trinitrobenzyl chloride (TNBCl) and hexanitrobibenzyl (HNBB) with sodium hypochlorite. The yields of HNBB and TNBCl are both above80%. The solvent, the base, and available chlorine of the sodium hypochlorite are the three key factors of the oxidation. Acetic ether is replaced to THF as solvent for the production of HNBB. The mechanism is discussed and the function of the alcohol that it can connect base with TNT is studied.A simple and effective oxidative dehydrogenation of HNBB to hexanitrostilbene (HNS) is developed using a mixture of2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) or N-hydroxyphthalimide (NHPI) and metal salts (FeCl2) as catalyst in DMSO under an atmospheric pressure of oxygen. The yield of HNS is80%with TEMPO, while that is70%with NHPI. A possible mechanism of this catalytic process is proposed, and the catalyst system TEMPO/FeCl2is successful used in the dehydrogenation of other nitro derivatives of bibenzyl. With the C-H and C-N bond dissociation energy of HNBB, the comparison of catalyst activities between TEMPO and NHPI is discussed. And the efficient and more environmentally friendly method is proved to be a better selection when compared to other previous methods, such as Shipp and Kaplan’s method.PEG1000-based functional dicationic acidic ionic liquid (PEG1000-DAIL) is used for the first time as the reaction solvent for NHPI/Co(OAc)2or N’, N", N’",-trihydroxyisocyanuric acid (THICA)/Co(OAc)2catalyzed aerobic oxidations of alkylaromatics to the corresponding acids. Several alkylaromatics are efficiently oxidized to their corresponding acids. With NHPI,99.9%conversion of toluene with99.5%selectivity for benzoic acid could be obtained, and the xylene is oxidized to the corresponding methylbenzoic acid. The oxidation of toluene is catalyzed by THICA/Co(OAc)2benzoic acid in99.0%selectivity at99.5%conversion. Using xylenes as the substrates is obtained the diacids, and nitrotoluene can be oxidized. This procedure includes many advantages such as mild reaction conditions, simplicity of operation, high yields, easy isolation of products by a simple decantation and excellent recyclability of the catalytic system.The novel and efficient catalytic systems THICA/dimethylglyoxime (DMG) and THICA/manganese binoxide (MNO2) are described for the selective oxidation of toluene derivatives with dioxygen in PEG1000-DAIL, respectively. With THICA/DMG system, the conversion of toluene is99.0%and the selectivity of benzoic acid is99.0%. When THICA/MnO2system is used, the conversion is99.8%and the selectivity is99.0%, respectively. Several toluene derivatives with electron-rich or electron-deficient substituted group are efficiently oxidized to corresponding acids under mild conditions. Based on the experimental observations, a possible mechanism is proposed. Both the catalyst and PEG1000-DAIL could be reused at least eight times without significantly decreasing the catalytic activity.更多还原