苯胺类化合物气相及水体中降解机理的理论研究

发布时间：2018-04-27 01:17

本文选题：量子化学计算 + ANs　；参考：《山东大学》2015年硕士论文

【摘要】：苯胺类化合物(Anilines, ANs)作为最简单的芳香胺类化合物,在工业中常被用作生产多种化学物质的原料或中间体,并随各种工业活动产生的废水废渣排放到环境中。ANs难以通过水体中微生物的自然降解作用去除,并具有环境持久性和生物蓄积性等特点。ANs大都具有很强的毒性,在水体中会对水生生物造成极大威胁,并通过生物富集作用最终影响人体健康。多数ANs可以通过吸入、食入或皮肤接触等方式进入人体并导致人体中毒。ANs会对人体的血液系统和神经系统造成损害,甚至会引起溶血性黄疸、肾损害或中毒性肝炎等疾病。另有一些ANs对人体和动物具有致突变性、致畸性和潜在致癌性,严重危害生物健康。因此,研究ANs在环境中降解的微观机理并找到有效的降解路径具有极其重要的环境意义及社会意义。本文选用对硝基苯胺(p-NA)、对硝基苯酚(p-NP)和对氯苯胺(p-CA)作为模型化合物,采用量子化学及反应动力学方法,对模型化合物在气相环境和水溶液中的降解机理和反应速率常数进行了系统研究,以期能够初步揭示典型ANs化学转化过程的微观机制,为有效去除环境中的ANs提供理论依据和数据参考。(1)OH自由基在大气和水溶液中均可与p-NA发生反应。计算结果表明,在气相环境中,OH自由基引发的加成反应比H抽提反应更易进行,其中,氨基邻位C加成和抽提氨基上的H分别是两种反应中最易发生的。反应主产物为对硝基苯酚、2-氨基-5-硝基酚、5-氨基-2-硝基酚和对氨基苯酚。初级反应生成的中间产物可与02进行后续反应,生成含双氧五元或六元环的化合物,并最终发生苯开环反应。其中,邻位和间位的加成产物可与O2发生多步反应,分别生成2-氨基-5-硝基酚和5-氨基-2-硝基酚。水溶液中,起绝对主导作用的是OH加成反应。在298 K,760Torr下,p-NP与OH自由基反应的总包速率为6.97×10-11 cm3molecule-1 s-1,与实验数据吻合。计算得到p-NA的大气寿命为4.1小时。(2)p-NP与OH自由基可以发生OH加成和H抽提两种反应。在气相环境中,两种反应具有竞争性,最易生成的加成产物和H抽提产物分别是1,2-二羟基-4-硝基环己基二烯自由基和4-氨基苯氧自由基。在水环境中,OH加成过程均为无垒反应,且放热量较高,比H抽提反应更容易进行。H02自由基和H原子也可与p-NP发生加成反应,但在气相环境中竞争力较小。水环境中H02加成反应较之于气相过程更易进行。OH自由基与p-NP反应生成的中间体可与OH自由基、H02自由基和O2等发生后续反应,并最终生成苯酚、对二苯酚、苯基-1,2,4-三醇、苯醌、4-硝基苯基-1,2-二醇、5-硝基苯基-1,2,3-三醇和4-硝基环己基-3,5-二烯-1,2-二酮等产物,水溶液中的反应总体比气相环境中容易进行。在298 K,760 Torr下,p-NP与OH自由基发生的初始反应总速率为1.4×10-13 cm3 molecule'1 s-1,加成反应与H抽提反应的分支比分别为0.49和0.51,说明气相环境中加成反应和H抽提反应具有竞争关系。(3)比较p-CA与OH自由基在水溶液中的反应,氨基邻位C的OH加成最易进行,其次是氨基上的H抽提反应。各加成产物可通过单分子分解反应或H抽提反应生成稳定产物对氯苯酚、2-氨基-5-氯酚、5-氨基-2-氯酚和4-氨基酚。另外,邻位和间位OH加成产物可与02发生加成反应,并生成产物2-氨基-5-氯酚和5-氨基-2-氯酚。2-氨基-5-氯酚可继续与OH自由基反应,生成稳定产物4-氯苯基-1,2-二醇、5-氯苯基-1,2,3-三醇和3-氨基-6-氯苯基-1,2-二醇。4-氯苯基-1,2-二醇可与02发生加成反应,并打开苯环,使p-CA的彻底降解能够发生。抽提氨基H得到的中间体也可与02加成,生成含双氧五元或六元杂环的化合物,并完成p-CA中氨基到硝基的转化,生成产物1-氯-4-硝基苯。在298 K,760 Torr条件下,p-CA与OH自由基反应的总速率为8.28×10-11 cm3 molecule-1 s-1,与实验结果一致。在200-400 K温度范围内,p-CA与OH自由基的反应速率与温度呈负相关。
[Abstract]:Anilines (ANs), as the simplest aromatic amine compound, is often used as a raw material or intermediate for the production of a variety of chemical substances in industry. And with the effluent from various industrial activities to the environment,.ANs is difficult to be removed by the natural degradation of microorganisms in the water, and has environmental persistence and survival. Most of the.ANs has a strong toxicity, which can cause a great threat to aquatic organisms in water, and ultimately affect human health through biological enrichment. Most ANs can enter the human body through inhalation, feeding or skin contact and cause human poisoning.ANs to cause the blood system and nervous system of human body. Damage may even cause diseases such as hemolytic jaundice, kidney damage or toxic hepatitis. Some ANs have mutagenicity, teratogenicity and potential carcinogenicity to human and animal, and seriously harm biological health. Therefore, it is of great environmental significance to study the micromechanism of degradation of ANs in the environment and to find an effective degradation path. In this paper, we choose p-nitroaniline (p-NA), p-nitrophenol (p-NP) and p-chloro aniline (p-CA) as model compounds, and systematically study the degradation mechanism and reaction rate constants of the model compounds in the gas phase and aqueous solution by quantum chemistry and reaction kinetics methods, in order to reveal the typical ANs chemical conversion. The micromechanism of the process can provide theoretical basis and data reference for the effective removal of ANs in the environment. (1) OH free radicals can react with p-NA in the atmosphere and aqueous solution. The results show that in the gas phase, the addition reaction caused by the OH radical is more easy to carry out than the H extraction reaction, in which the amino ortho C addition and extraction of the amino group are on the amino group. H is the most easy to occur in the two reactions. The main products are p-nitrophenol, 2- amino -5- nitrophenol, 5- amino -2- nitrophenol and p-aminophenol. The intermediate product of the primary reaction can be followed up with 02 to produce compounds containing dioxygen five or six ring, and at the end of the benzene ring opening reaction. The addition product can react with O2 to produce 2- amino -5- nitrophenol and 5- amino -2- nitrophenol respectively. In aqueous solution, the absolute dominant effect is OH addition reaction. Under 298 K, 760Torr, the total packet rate of p-NP and OH free radical reaction is 6.97 x 10-11 cm3molecule-1 s-1, which is in agreement with the experimental data. The atmospheric life is calculated to be 4. .1 hours. (2) there are two reactions of OH addition and H extraction for p-NP and OH radicals. In the gas phase, two reactions are competitive. The most easily generated addition products and H extraction products are 1,2- two hydroxyl -4- nitrocyclohexadiene free radical and 4- amino Benzoxy radical. In water environment, OH addition process is no barrier reaction. The heat discharge is higher than the H extraction reaction. The.H02 free radical and H atom can also react with p-NP, but in the gas phase, the competitiveness is smaller. The H02 addition reaction in the water environment is more easy to carry out the intermediate of.OH free radical and p-NP reaction, which can be followed by the OH free radical, H02 radical and O2, etc. Finally, phenol, two phenol, phenyl -1,2,4- three alcohol, benzone, 4- nitrophenyl -1,2- diol, 5- nitro phenyl -1,2,3- three alcohol and 4- nitrocyclohexyl -3,5- diene -1,2- two ketone, the overall reaction in aqueous solution is easier than that in gas phase. Under 298 K, 760 Torr, the initial reaction rate of p-NP and OH radical is 1.. 4 * 10-13 cm3 molecule'1 s-1, the branching ratio of addition reaction and H extraction reaction is 0.49 and 0.51 respectively, indicating that the addition reaction and H extraction reaction in the gas phase have a competitive relationship. (3) the reaction of p-CA and OH radicals in the aqueous solution, the OH addition of the amino group C is the most easy to be carried out, followed by the H extraction reaction on the amino group. Each addition product can be added. The stable products of chlorophenol, 2- amino -5- chlorophenol, 5- amino -2- Chlorophenol and 4- aminophenol were produced by the single molecular decomposition reaction or H extraction reaction. In addition, the adjoining and interposition OH addition products can react with 02, and the product of 2- amino -5- Chlorophenol and 5- amino -2- chlorophenol.2- ammonia radical chlorophenol can continue to react with the free radical and produce stability. The product 4- chlorophenyl -1,2- glycol, 5- chlorophenyl -1,2,3- three alcohol and 3- amino -6- chlorophenyl -1,2- glycol.4- chlorophenyl -1,2- diol can react with 02, and open the benzene ring, so that the radical degradation of p-CA can occur. The intermediate of H obtained by the extraction of amino group can also be added to 02 to produce a compound containing five yuan or six membered heterocyclic rings and completed p-CA. The transformation of middle amino to nitro group, producing 1- chlorine -4- nitrobenzene. Under 298 K and 760 Torr conditions, the total rate of p-CA and OH radical reaction is 8.28 * 10-11 cm3 molecule-1 s-1, which is in agreement with the experimental results. The reaction rate of p-CA to OH free radicals is negatively correlated with the temperature of the OH free radicals in the temperature range of 200-400 K.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X131.2

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