金属配位诱导的酚酸酯与氮氧化物的高选择性直接重氮化反应

发布时间：2018-11-15 18:36

【摘要】：氮氧化物是一类“奇异的”氧化物。低浓度下时,充当着生物体内的信号传递分子;高浓度下,却是有毒气体,是造成大气污染的主要污染源之一。这与氮氧化物的物种多样性(氮价态在+1到+4)以及转变的可逆性相关,常能呈现出一些奇异的性质。本文主要研究氮氧化物在金属离子诱导下与酚酸酯反应,发生直接高选择性重氮化反应的条件与机理。研究结果证明:在没有金属离子作用下,过量氮氧化物只与水杨酸甲酯发生少量的硝基化反应。但当存在金属离子(RE3+,Zn2+,Cu2+,Ni2+,Ca2+等)的高氯酸盐时,过量氮氧化物与水杨酸酯能够发生直接的重氮化反应,得到高选择性的5-重氮基水杨酸甲酯高氯酸盐,并以结晶的形式从反应体系析出。对反应过程中反应物的配比(稀土离子与水杨酸甲酯的摩尔比)、氮氧化物的通入速度、反应时间、反应温度以及反应溶剂等因素对这一重氮化反应的影响研究结果证明:该反应的发生主要经历了金属离子对水杨酸甲酯的配位活化、三氧化二氮对酚羟基对位氢的直接取代、后续氮氧化物对取代中间体的连续还原和重氮化合物的结晶析出等阶段。结合反应过程的红外光谱、紫外可见光谱以及质谱分析数据,认为具有邻羟基苯甲酰结构的化合物(除水杨酸)由于苯环上酚羟基及邻位羰基与金属离子发生螯合配位,使对位和邻位的氢得到活化,而取代反应是由氮氧化物整个分子(N2O3或N2O3H+)直接进攻的,由于空间位阻效应,使取代反应只发生在对位,得到高选择性的羟基对位重氮化产物。该重氮化反应没有经历亚硝基水杨酸甲酯这一中间态物质,而是通过N2O3(或N2O3H+)直接接入苯环,离去H+,得到-NONO2结构;随后在溶液中的还原性物质(如NO+/HNO2)作用下,将多余的氧原子带离,得到重氮盐。并且证明SO2也可以作为还原剂。基于金属邻羟基苯甲酰类酚酸酯配合物在乙酸丁酯溶液中与过量氮氧化物接触能够发生重氮化反应,得到重氮盐结晶的现象,研究了多级吸收瓶对氮氧化物的吸收情况,并提出了一套将有毒害性的氮氧化物转变为有用重氮盐化合物的方法。
[Abstract]:Nitrogen oxides are a class of "strange" oxides. At low concentration, it acts as a signal transporter in organisms, but at high concentration, it is a toxic gas, which is one of the main sources of air pollution. This is related to the species diversity of nitrogen oxides (the valence of nitrogen is between 1 and 4) and the reversibility of the transition. In this paper, the conditions and mechanism of direct selective diazotization of nitrogen oxides with phenolic acid esters induced by metal ions are studied. The results show that the nitration of excess nitrogen oxides with methyl salicylate occurs only in the absence of metal ions. However, in the presence of perchlorates with metal ions (RE3, Zn2, Cu2, Ni2, Ca2, etc.), excessive nitrogen oxides can react directly with salicylate to obtain highly selective 5-diazo methyl salicylate perchlorates. And precipitated from the reaction system in the form of crystallization. The ratio of reactants (molar ratio of rare earth ions to methyl salicylate), the penetration rate of nitrogen oxides, the reaction time, The effects of reaction temperature and solvent on the diazotization reaction were studied. The results showed that the reaction mainly underwent the coordination activation of methyl salicylate by metal ions, and the direct substitution of p-phenolic hydroxyl hydrogen by nitrogen trioxide. Continuous reduction of substituted intermediates and crystallization of diazo compounds by subsequent nitrogen oxides. In combination with the IR, UV-Vis and MS analysis data of the reaction process, it is considered that the compounds with o-hydroxybenzoyl structure (desalicylic acid) chelate and coordinate with metal ions due to phenolic hydroxyl groups and O-carbonyl groups in benzene ring. The substitution reaction was directly attacked by the whole nitrogen oxide molecule (N2O3 or N2O3H). Due to the steric effect, the substitution reaction only occurred in the para-site, resulting in highly selective hydroxy p-diazotization products. The diazotization reaction did not go through the intermediate state of methyl nitrosalicylate, but via N2O3 (or N2O3H) directly into the benzene ring, leaving H, to obtain-NONO2 structure; Then the excess oxygen atoms were separated from the excess oxygen atoms under the action of reductive substances (such as NO / HNO2) in the solution to obtain diazo salts. It is also proved that SO2 can also be used as reducing agent. Based on the diazotization reaction of metal o-hydroxybenzoyl phenolic acid complexes in butyl acetate solution with excess nitrogen oxides, the crystallization of diazo salts was obtained. The absorption of nitrogen oxides in multistage absorption bottles was studied. A method for converting toxic nitrogen oxides into useful diazo salt compounds is proposed.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O621.25

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