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Phenol in Mixed Acid Benzene Nitration Systems
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2018-11-09 , DOI: 10.1021/acs.iecr.8b04226
Diogo Afonso 1, 2, 3 , Alejandro. F.G. Ribeiro 1 , Paulo Araújo 1 , Joaquim Vital 2 , Luis M. Madeira 3
Affiliation  

Phenol was detected for the first time in the mononitrobenzene production process by benzene adiabatic nitration, supporting the theory that proposes phenol as the precursor of nitrophenols, unwanted byproducts. For that, analytical procedures (based in liquid and gas chromatographic techniques) have been developed and improved that aim to detect these chemical species both in the industrial nitration process as well as in laboratory tests at different reaction conditions. The obtained results confirmed the proposed and accepted mechanism for the nitrophenols formation during benzene nitration, showing that phenol is indeed the nitrophenolic byproducts precursor. Moreover, it is shown the phenol’s high reactivity even at smooth reaction conditions (namely low temperature and low sulfuric acid concentration), which explains the difficulty of detecting this compound within the reaction medium using the analytical techniques applied for monitoring benzene nitration process. In this study, it was also discovered that 4-mononitrophenol had higher affinity into the aqueous acid phase when compared to the other nitrophenolic byproducts (2-mononitrophenol; 2,4-dinitrophenol; 2,6-dinitrophenol; and 2,4,6-trinitrophenol) that have more affinity into the organic phase. Phenol distribution between both reaction phases was found to be similar to the majority of the nitrophenols, i.e., it is present in higher concentration in the organic phase.

中文翻译:

混合酸苯硝化系统中的苯酚

苯绝热硝化法在单硝基苯生产过程中首次检测到苯酚,这支持了提出将苯酚用作硝基苯酚(不想要的副产物)的前体的理论。为此,已经开发和改进了分析程序(基于液相色谱和气相色谱技术),旨在检测工业硝化过程以及实验室中不同反应条件下的这些化学物种。获得的结果证实了在苯硝化过程中形成硝基酚的提议的和可接受的机理,表明苯酚确实是硝基酚副产物的前体。此外,显示出即使在平稳的反应条件下(即低温和低硫酸浓度),苯酚也具有高反应活性,这解释了使用用于监测苯硝化过程的分析技术在反应介质中检测该化合物的困难。在这项研究中,还发现与其他硝基酚副产物(2-单硝基苯酚,2,4-二硝基苯酚,2,6-二硝基苯酚和2,4,6)相比,4-一硝基苯酚对水酸相的亲和力更高。 -三硝基苯酚)对有机相具有更高的亲和力。发现两个反应相之间的苯酚分布与大多数硝基苯酚相似,即,它以较高的浓度存在于有机相中。还发现,与其他硝基酚副产物(2-单硝基苯酚,2,4-二硝基苯酚,2,6-二硝基苯酚和2,4,6-三硝基苯酚)相比,4-一硝基苯酚对水酸相的亲和力更高。对有机相有更多的亲和力。发现两个反应相之间的苯酚分布与大多数硝基苯酚相似,即,它以较高的浓度存在于有机相中。还发现,与其他硝基酚副产物(2-单硝基苯酚,2,4-二硝基苯酚,2,6-二硝基苯酚和2,4,6-三硝基苯酚)相比,4-一硝基苯酚对水酸相的亲和力更高。对有机相有更多的亲和力。发现两个反应相之间的苯酚分布与大多数硝基苯酚相似,即,它以较高的浓度存在于有机相中。
更新日期:2018-11-10
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