Insights into Different Products of Nitrosobenzene and Nitrobenzene Hydrogenation on Pd(111) under Realistic Reaction Conditions,The Journal of Physical Chemistry C

当前位置： X-MOL 学术 › J. Phys. Chem. C › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Insights into Different Products of Nitrosobenzene and Nitrobenzene Hydrogenation on Pd(111) under Realistic Reaction Conditions
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-08-27 , DOI: 10.1021/acs.jpcc.8b05364
Lidong Zhang ₁ , Zheng-Jiang Shao ₁ , Xiao-Ming Cao ₁ , P. Hu _{1,

2}

Affiliation

Selective hydrogenation of nitroarene compounds is applied in many fields such as agrochemicals, pharmaceuticals, and dyes. Pd-catalyzed hydrogenation of nitrobenzene (PhNO₂) and nitrosobenzene (PhNO) could exhibit different selectivities. This was regarded as the evidence to challenge the Haber mechanism for PhNO₂ hydrogenation in which PhNO is an important intermediate. In this study, we systematically investigate their hydrogenation mechanisms under realistic reaction conditions based on first-principles calculations. It is found that the weak bonding between the nitro group and the Pd(111) surface leads to the flat-lying chemisorption configuration of PhNO₂ and the other intermediates during PhNO₂ hydrogenation. In contrast, the strong bonding between the nitroso group and the surface makes PhNO switch its chemisorption mode from flat-lying adsorption under the ultrahigh vacuum condition to vertical adsorption under reaction conditions. For the flat-lying PhNO₂, the chemisorbed phenyl group makes hydrogenation easier but hinders N–O bond breaking, resulting in the production of PhNH₂ via a direct pathway. Conversely, without the hinderance of the chemisorbed phenyl group, N–O bond breaking and N–N coupling become more favorable during the reduction of vertical PhNO* toward the formation of azoxy compound on Pd(111). These results unveil the fact that the difference between the selectivities of PhNO₂ and PhNO hydrogenation is independent of the formation of PhNO* but dependent on the phenyl group adsorption mode.

中文翻译：

在实际反应条件下对Pd（111）上亚硝基苯和硝基苯加氢不同产物的见解

硝基芳烃化合物的选择性加氢应用于许多领域，例如农用化学品，药物和染料。Pd催化的硝基苯（PhNO ₂）和亚硝基苯（PhNO）的加氢选择性不同。这被认为是挑战PhNO ₂加氢的Haber机制的证据，其中PhNO是重要的中间体。在这项研究中，我们基于第一性原理计算系统地研究了它们在现实反应条件下的加氢机理。发现硝基和Pd（111）表面之间的弱键导致PhNO ₂和PhNO ₂期间其他中间体的平坦化学吸附构型氢化。相反，亚硝基与表面之间的强键使PhNO将其化学吸附模式从超高真空条件下的平坦吸附转变为反应条件下的垂直吸附。对于平坦的PhNO _2来说，化学吸附的苯基使氢化更容易，但阻碍了N–O键的断裂，从而导致通过直接途径生成PhNH ₂。相反，在没有化学吸附的苯基的情况下，在垂直的PhNO *还原过程中，Pd（111）上形成叠氮化合物时，N-O键断裂和N-N偶联变得更加有利。这些结果揭示了PhNO ₂选择性之间的差异的事实。 PhNO的氢化与PhNO *的形成无关，但取决于苯基的吸附方式。

更新日期：2018-08-28

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南