Reaction mechanism of tert-butylation of phenol with tert-butyl alcohol over H-beta zeolite: An ONIOM study
发表时间：2019-03-09
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- 论文类型：
- 期刊论文
- 第一作者：
- Nie, Xiaowa
- 通讯作者：
- Guo, XW (reprint author), Dalian Univ Technol, Sch Chem Engn, State Key Lab Fine Chem, POB 39,158 Zhongshan Rd, Dalian 116012, Peoples R China.
- 合写作者：
- Janik, Michael J.,Guo, Xinwen,Liu, Xin,Song, Chunshan
- 发表时间：
- 2011-05-16
- 发表刊物：
- CATALYSIS TODAY
- 收录刊物：
- SCIE、EI
- 文献类型：
- J
- 卷号：
- 165
- 期号：
- 1
- 页面范围：
- 120-128
- ISSN号：
- 0920-5861
- 关键字：
- Phenol; Tert-butylation; H-beta; Zeolite; Reaction mechanism; ONIOM
- 摘要：
- Tert-butylation of phenol with tert-butyl alcohol (TBA) over H-beta zeolite was studied using the ONIOM approach with two proposed reaction paths: stepwise and concerted mechanisms. The results obtained by the ONIOM2 (B3LYP/6-31G(d,p):UFF) method reveals that the tert-butylation of phenol preferentially occurs through a co-adsorbed, concerted mechanism without prior dehydration of tert-butyl alcohol, rather than via a stepwise mechanism through dehydration to form tert-butyl carbenium ion as the first step followed by tert-butyl cation attack on the 2- or 4-position on phenol. The kinetic difference between 2- and 4-tert-butylation is more apparent in the concerted path, where 4-tert-butylation proceeds over a lower activation barrier. Decreasing the acid site strength, via substitution of Ga for Al, reduces the H-bonding interaction between the zeolitic proton and tert-butyl alcohol and increases the apparent activation barriers, which slows the overall reaction, and also lowers the selectivity to 4-tert-butyl phenol. (c) 2010 Elsevier B.V. All rights reserved.
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- 否
