气液反应本征动力学研究策略及其在氧化反应中的应用

发布时间：2017-12-27 23:01

本文关键词：气液反应本征动力学研究策略及其在氧化反应中的应用　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：液相空气氧化是以氧气或空气为氧化剂,反应发生在液相区域的多相反应。多相反应的特点决定液相空气氧化是传质因素与本征反应耦合的过程。但是,很多研究者在开展氧化反应过程分析、动力学探究、机理分析以及催化剂设计等工作时,忽略传质因素,容易给同行研究者带来误导。而反应本征动力学是不受传质参数影响下的反应动力学信息,是多相反应中反应信息的最本征体现。气液本征动力学研究策略可描述为:当本征反应为慢反应或极慢反应时,可通过强化传质过程消除传质阻力,本征动力学研究类同均相反应;对于中速反应或快速反应,传质阻力很难完全排除,可通过解耦宏观动力学策略获得本征动力学信息;对于瞬间反应本征动力学无法求解,需改变反应参数,调整动力学区域、改变反应类型,再进一步进行本征动力学分析。本文在对气液反应本征动力学探究规律进行梳理的基础上,以4-甲基愈创木酚液相氧化合成香兰素以及(3 S,7R,7aR)-6-苄基-7-(1-羟基-2-氧环己基)-3-苯基四氢化-5H-咪唑[1,5-c][1,3]噻唑-5-酮液相氧化合成6-[(3S,7R,7aR)-苄基-5-氧-3-苯基四氢化-1H-咪唑[1,5-c][1,3]噻唑-7-基]-6-氧己酸为研究对象,探究香兰素以及生物素中间体两个重要氧化体系的本征动力学,并将本征动力学相关信息用于反应机理等问题的探究中去。逻辑实验、柱分析以及液相色谱质谱联用等手段证明4-甲基愈创木酚液相氧化可描述为4-甲基愈创木酚氧化生成芳醚中间体,中间体进一步氧化生成香兰素的连串反应。传质分析实验表明4-甲基愈创木酚氧化连串反应两步均可视为拟一级快速反应,反应发生区域主要集中在液膜内,由此确定本征动力学探究策略。在满足碳平衡要求并计算物性参数与传质参数的前提下,探究了反应本征动力学。动力学结果表明4-甲基愈创木酚氧化生成芳醚中间体反应活化能为31.95 kJ/mol,中间体氧化生成香兰素反应活化能为29.77 kJ/mol。不同氧气压力、催化剂浓度实验表明,连串反应的两步对氧气以及催化剂均为一级反应。同时,溶剂探究实验证明连串反应的两步对乙二醇甲醚均为零级反应。反应副产物网络分析表明,自由基聚合产生的低聚物为反应主要副产物。本征动力学指导机理探究结果表明:4-甲基愈创木酚液相氧化反应速率控制步骤是酚氧负离子的催化氧化,亚甲基醌主要通过催化氧化获得,反应过程中醇类溶剂与亚甲基醌1,6-加成反应形成芳醚化合物,提高氧自由基向亚甲基梖的转变速率是提高反应选择性的关键所在,反应产物中的少量香兰酸是通过Cannizzaro歧化生成的。碱作为对甲酚类化合物氧化反应中的关键组分,其作用机理可描述为:碱与底物酚进行酸碱反应形成酚氧负离子活化反应底物;碱通过与催化剂作用或单独作用,加快酚氧自由基催化氧化生成亚甲基醌,抑制了偶合终止反应,降低低聚物的生成;碱参与了醛的歧化反应,但反应速率很慢,碱并不是醛深度氧化的抑制剂;碱的最优使用量和溶剂的种类、水含量是相关的,无水条件或pKa值比较低的溶剂对反应体系有利。为进一步验证碱作用机理,设计了无钴催化剂下香兰醇及系列化合物的碱催化氧化,实验现象与碱作用机理吻合。实验还首次提出了无过渡金属条件下的碱催化氧化合成对羟基苯甲醛类化合物新路线。(3S,7R,7aR)-6-苄基-7-(1-羟基-2-氧环己基)-3-苯基四氢化-5H-咪唑[1,5-c][1,3]噻唑-5-酮液相氧化主反应可描述为简单反应,反应过程没有检测出明显中间体。不同搅拌转速以及通气速率下的传质实验表明,该氧化反应为动力学控制,反应主要发生在液相主体区。(3S,7R,7aR)-6-苄基-7-(1-羟基-2-氧环己基)-3-苯基四氢化-5H-咪唑[1,5-c][1,3]噻唑-5-酮液相氧化可描述为生成目标产物酮酸为主反应,卤代反应与羰基另一侧的C-C键断裂为副反应的平行反应。卤代副反应对氧气反应级数为零级,C-C键断裂氧化反应对氧气为一级反应。催化剂浓度升高,主反应与副反应速率均增加,对催化剂反应级数均为1级。其中,主反应活化能为54.67 kJ/mol,卤代副反应活化能为105.44 kJ/mol,另一侧的C-C键断裂反应活化能为88.67 kJ/mol,该结论与八田数等证据证明了慢反应动力学结论。红外与紫外相关数据表明催化剂的主要结构为[Fe(DMSO)4C12]Cl,溶剂起着溶解与配体的双攻能作用,氧配体对催化剂活性起积极作用。该体系与传统甲基环己酮类似体系差异主要在于位阻效应,位阻效应可通过增加催化剂的量进行克服,可利用位阻效应调控反应进行的方向。自由基猝灭实验与自由基捕获实验证明该氧化反应是自由基机理和离子型机理共同作用的结果,二者比例为52:48,这也与本征动力学结论一致。
[Abstract]:Liquid air oxidation is a multiphase reaction that takes oxygen or air as an oxidant, and the reaction occurs in the liquid phase. The characteristics of the multiphase reaction determine that the liquid air oxidation is the process of coupling the mass transfer factor with the intrinsic reaction. However, many researchers ignore the factors of mass transfer during the process of oxidation reaction analysis, dynamic exploration, mechanism analysis and catalyst design. The reaction intrinsic kinetics is the dynamic information of the reaction under the influence of the mass transfer parameters, and is the most important manifestation of the reaction information in the multiphase reaction. Research on the intrinsic kinetics gas-liquid strategy can be described as: when the intrinsic reaction is slow or very slow reaction, mass transfer resistance can be eliminated by strengthening the mass transfer process, the intrinsic kinetic study of similar homogeneous reaction; for medium reaction or rapid reaction, mass transfer resistance is difficult to completely eliminate, can obtain the intrinsic kinetic information through macro decoupling dynamic strategy; for the moment the intrinsic reaction kinetics can not be solved, the need to change the reaction parameters, adjust the dynamic area, change the type of reaction, further analyzes the intrinsic kinetics. Based on the gas-liquid reaction the intrinsic kinetics of exploring the law on carding, by 4- methyl guaiacol oxidation in liquid phase synthesis of vanillin and (3 S, 7R, 7aR) -6- benzyl -7- (1- hydroxy -2- oxocyclohexyl) synthesis of 6-[-3- four phase oxidation of phenyl imidazole thiazole ketone hydrogenation of -5H- [1,5-c][1,3] -5- (3S fluid 7R, 7aR, -5-) - benzyl oxygen -3- phenyl four hydrogenated -1H- imidazo [1,5-c][1,3] thiazole -7- base]-6- oxygen acid as the research object, to explore the intrinsic kinetics of two important oxidation system of vanillin and biotin intermediates, and the intrinsic kinetic information for exploring the reaction mechanism in the. Logical experiments, column analysis and liquid chromatography-mass spectrometry proved that 4- methyl guaiacol liquid phase oxidation can be described as 4- methyl guaiacol oxidation to produce aromatic ether intermediates, and intermediates are further oxidized to produce vanillin. The mass transfer analysis experiments showed that the two steps of 4- methyl guaiacol oxidation and consecutive reaction were regarded as pseudo first order rapid reaction. The reaction area was mainly concentrated in the liquid membrane, so the intrinsic kinetics inquiry strategy was determined. In order to meet the requirements of carbon balance and to calculate the physical and mass transfer parameters, the reaction intrinsic kinetics is explored. The kinetic results showed that 4- methyl guaiacol was oxidized to produce aromatic ether intermediate, the reaction activation energy was 31.95 kJ/mol, and the activation energy of intermediate oxidation to vanillin was 29.77 kJ/mol. The experiment of different oxygen pressure and catalyst concentration showed that the two steps of the series reaction were first order reaction to oxygen and catalyst. At the same time, the solvent inquiry experiment proved that the two step of the series reaction was zero order reaction to ethylene glycol methyl ether. The reaction byproduct network analysis showed that the oligomer produced by the free radical polymerization was the main reaction product. The kinetic mechanism of guiding the results show that: 4- methyl guaiacol oxidation in liquid phase reaction rate controlling step is the catalytic oxidation of phenol oxygen negative ion, Ya Jiaji quinones mainly obtained through catalytic oxidation reaction process in alcohol solvent and Ya Jiaji addition reaction to form quinone 1,6- aryl ether compounds, improve the oxygen free radical to the change rate of the Ya Jiaji Bei is the key to improve the selectivity of reaction, a small amount of vanillic acid in the reaction product is generated by Cannizzaro disproportionation. As a key group of compounds of alkali oxidation reaction of cresol, its mechanism can be described as: alkali phenol and substrate of acid-base reaction formation of phenolic oxygen negative ion activation by alkali catalyst and substrate; or individually, accelerate the phenoxy radical generation of catalytic oxidation of methylene quinone, inhibited the coupling termination reaction. Reduction of oligomer formation; alkali in the disproportionation reaction of aldehydes, but the reaction rate is very slow, and not the aldehyde oxidation inhibitor alkali; alkali amount and optimal use of solvent, water content is related to the anhydrous conditions or pKa value relatively low solvent is favorable to the reaction system. In order to further verify the base mechanism, designed and vanillyl alcohol series compound alkali catalytic oxidation of cobalt free catalyst. The experimental results agree well with the mechanism of alkali. It is also the first time that a new route for the synthesis of hydroxy benzaldehyde under the condition of non transition metal is also proposed. (3S, 7R, 7aR) -6- benzyl -7- (1- hydroxyl -2- oxygen cyclohexyl) -3- phenyl four hydrogenation, -5H-, imidazole, [1,5-c][1,3] thiazolone, the main reaction of liquid phase oxidation can be described as simple reaction, and no obvious intermediate has been detected in the reaction process. The mass transfer experiments under different stirring speed and aeration rate show that the reaction is controlled by kinetics, and the reaction occurs mainly in the main liquid phase. (3S, 7R, 7aR) -6- benzyl -7- (1- hydroxyl -2- oxygen cyclohexyl) -3- phenyl four hydrogenation, -5H-, imidazole, [1,5-c][1,3] thiazolone, liquid phase oxidation can be described as the target product, keto acid as the main reaction, halogenation reaction with the side bond of the carbonyl on the other side as a parallel reaction of side reactions. The reaction order of the halogenated side reaction to oxygen is zero, and the C-C bond oxidation reaction is a first-order reaction to oxygen. As the concentration of catalyst increases, both the main reaction and the secondary reaction rate increase, and the reaction order of the catalyst is 1. The activation energy of the main reaction is 54.67 kJ/mol, the activation energy of halogenation reaction is 105.44 kJ/mol, and the activation energy of C-C bond breaking reaction on the other side is 88.67 kJ/mol, which is proved by the eight field number and other evidences. The IR and UV correlation data indicate that the main structure of the catalyst is [Fe (DMSO) 4C12]Cl. The solvent plays a dual role in the dissolution and ligand interaction, and the oxygen ligand plays a positive role in the activity of the catalyst. The difference between the system and traditional methyl cyclohexanone is mainly the steric hindrance effect. The steric hindrance effect can be overcome by increasing the amount of catalyst, and the direction of reaction can be controlled by steric effect. Free radical quenching experiment and free radical
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.1

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