使用对氢对呋喃衍生物进行非均相加氢的机理研究,ChemCatChem

当前位置： X-MOL 学术 › ChemCatChem › 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.)

使用对氢对呋喃衍生物进行非均相加氢的机理研究
ChemCatChem ( IF 3.8 ) Pub Date : 2018-02-05 , DOI: 10.1002/cctc.201701653
Oleg G. Salnikov _{1,

2} , Larisa M. Kovtunova _{2,

3} , Ivan V. Skovpin _{1,

2} , Valerii I. Bukhtiyarov _{2,

3} , Kirill V. Kovtunov _{1,

2} , Igor V. Koptyug _{1,

2}

Affiliation

已证明对氢诱导极化（PHIP）是一种有用且独特的技术，用于研究涉及氢的催化反应的机理。本文将PHIP用于二氧化钛负载的Rh，Pd和Pt催化剂上呋喃，2,3-二氢呋喃和2,5-二氢呋喃的气相加氢机理研究。在Rh / TiO ₂催化剂上所有三个底物的氢化反应中，PHIP技术揭示了可能从同一H ₂分子中成对添加两个H原子，形成四氢呋喃分子，同时保持所添加质子之间的自旋相关性。Rh / TiO _2上的2,3-二氢呋喃加氢在催化剂中，不仅在四氢呋喃中还检测到PHIP效应，还在杂环的2和3位上检测到反应物（2,3-二氢呋喃）。这样出乎意料的结果是2,3-二氢脲醛中氢原子成对替换的直接证据。这种成对替换的可能机理包括添加和消除氢原子的顺序步骤。相反，如果在Rh / TiO _2上进行2,5-二氢呋喃的氢化反应，则会检测到所有2,3-二氢呋喃质子的PHIP效应，这意味着2,3-二氢呋喃可能由2,5-二氢呋喃形成。不仅是通过C = C键的异构化，而且还包括将2,5-二氢呋喃脱氢为呋喃并随后进行半氢化。

"点击查看英文标题和摘要"

Mechanistic Insight into the Heterogeneous Hydrogenation of Furan Derivatives with the use of Parahydrogen

Parahydrogen‐induced polarization (PHIP) was shown to be a useful and unique technique to study the mechanisms of catalytic reactions involving hydrogen. In this paper, PHIP was utilized for mechanistic investigation of the gas‐phase hydrogenation of furan, 2,3‐dihydrofuran, and 2,5‐dihydrofuran over titania‐supported Rh, Pd, and Pt catalysts. In the hydrogenation of all three substrates over the Rh/TiO₂ catalyst, the PHIP technique revealed the possibility of pairwise addition of two H atoms from the same H₂ molecule with the formation of tetrahydrofuran molecules while retaining spin correlation between the added protons. In the hydrogenation of 2,3‐dihydrofuran over the Rh/TiO₂ catalyst, PHIP effects were detected not only for tetrahydrofuran but also for the reactant (2,3‐dihydrofuran) at positions 2 and 3 of the heterocyclic ring. Such unexpected results are direct evidence for the pairwise replacement of the hydrogen atoms in 2,3‐dihydorfuran. A probable mechanism for this pairwise replacement includes sequential steps of addition and elimination of hydrogen atoms. In contrast, if the hydrogenation of 2,5‐dihydrofuran was performed over Rh/TiO₂, PHIP effects were detected for all protons of 2,3‐dihydrofuran, implying that 2,3‐dihydrofuran could be formed from 2,5‐dihydrofuran not only through isomerization of the C=C bond but also through dehydrogenation of 2,5‐dihydrofuran to furan with subsequent semihydrogenation.

更新日期：2018-02-05

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