How Does Azo Bond Cleave in the Gas Phase? Computational and Experimental Study on the Fragmentation Mechanism of Protonated Sudan I
How Does Azo Bond Cleave in the Gas Phase? Computational and Experimental Study on the Fragmentation Mechanism of Protonated Sudan I
复制标题
偶氮键如何在气相中裂解？
DOI：
10.1002/slct.201803165
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发表时间：
2019-02
期刊：
影响因子：
--
通讯作者：
江继军
中科院分区：
文献类型：
--
作者：
戚平;高辉;江继军
1-苯基偶氮-2-萘酚（苏丹红I）是一种廉价但有害的食品添加剂，近年来受到广泛关注，主要集中在HPLC-ESI-MS/MS检测方法上。然而，碎片化机制一般很少。本文采用电喷雾串联质谱和密度泛函理论（DFT）相结合的方法研究了质子化苏丹红I在气相中的裂解途径。最初，偶氮键的断裂是由电离质子从O-质子化的苏丹红I的氧原子通过六元环过渡态迁移到相邻的N原子引发的，导致单个离子中性络合物（INC-s）。随后，INC-s的直接分解得到m/z 156的萘酚氮烯离子。同时，INC-s可通过交叉点（INC-mecp）发生分子间单电子转移（SET）反应，生成由萘酚氮烯自由基和苯胺自由基离子组成的三元离子-中性络合物（INC-t）。最后，随着INC-t的分解，形成m/z 156的苯胺自由基离子。进一步的静电势图、自然布居分析（NPA）和前线分子轨道（FMOs）的计算结果与实验结果吻合较好。综上所述，我们的研究结果不仅为更好地了解苏丹红I提供了机理信息，而且也为食品工业中其他相关有害添加剂提供了见解。
As a cheap but harmful additive in food industry, 1-phenylazo-2-naphthol (Sudan I) has attracted lots of attentions, which mainly focused on the determinations using the HPLC-ESI-MS/MS techniques. However, the fragmentation mechanisms are generally scarce. In this paper, the fragmentation pathways of protonated Sudan I in gas-phase were investigated by a combination of electrospray ionization-tandem mass spectrometry and density functional theory (DFT) calculations. Initially, the cleavage of azo bond is triggered by ionizing proton migration from the oxygen atom of O-protonated Sudan I to adjacent N atom through a six-member ring transition state, leading to a single ion-neutral complex (INC-s). Subsequently, the direct decomposition of INC-s gives the naphtol nitrene ion at m/z 156. Meanwhile, INC-s may occur an intermolecular single electron transfer (SET) reaction via the crossing points (INC-mecp), affording the triple ion-neutral complex (INC-t) consisting of naphtol nitrene radical and aniline radical ion. Finally, followed by the decomposition of INC-t, the aniline radical ion at m/z 156 is formed. Further studies on Electrostatic potential map, Natural population analysis (NPA) and frontier molecular orbitals (FMOs) during the proposed mechanism are also found to be in good agreement with experimental observations. Taken together, our results presented here not only provide mechanistic information for better understanding the Sudan I, but also give insights into other related harmful additives in food industry.
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DOI：
10.1021/jo0609475
发表时间：
2006-06
期刊：
The Journal of organic chemistry
影响因子：
--
作者：
Jorge Freire de Queiroz;J. Carneiro;A. Sabino;R. Sparrapan;M. Eberlin;P. Esteves
通讯作者：
Jorge Freire de Queiroz;J. Carneiro;A. Sabino;R. Sparrapan;M. Eberlin;P. Esteves
DOI：
10.1007/s13361-012-0344-8
发表时间：
2012-05-01
影响因子：
3.2
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通讯作者：
Pan, Yuanjiang
影响因子：
15
作者：
Esteves, PM;Carneiro, JWD;Olah, GA
通讯作者：
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DOI：
10.1021/jo060439v
发表时间：
2006-06
期刊：
The Journal of organic chemistry
影响因子：
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作者：
Yaping Tu
通讯作者：
Yaping Tu
DOI：
10.1021/jo050398n
发表时间：
2005-05
期刊：
The Journal of organic chemistry
影响因子：
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作者：
Yaping Tu;Limin He;W. Fitch;Michelle Lam
通讯作者：
Yaping Tu;Limin He;W. Fitch;Michelle Lam