The Design of a Process

Reaction mechanism of tert-butylation of phenol with tert-butyl alcohol over H-beta zeolite: An ONIOM study | 作者: Nie, XW (Nie, Xiaowa)1,3,4; Janik, MJ (Janik, Michael J.)2; Guo, XW (Guo, Xinwen)1; Liu, X (Liu, Xin)1; Song, CS (Song, Chunshan)1,2,3,4 | 来源出版物: CATALYSIS TODAY 卷: 165 期: 1 页: 120-128 DOI: 10.1016/j.cattod.2010.11.070 出版年: MAY 16 2011 | 被引频次: 2 (来自 Web of Science) | 引用的参考文献: 50 [ 查看 Related Records ] 引证关系图 | 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. |

Vapor-Phase Alkylation of Phenol with Tert-butyl Alcohol Catalyzed by H3PO4/MCM-41 | 作者: Ghiaci, M (Ghiaci, Mehran)1; Aghabarari, B (Aghabarari, Behzad)1 | 来源出版物: CHINESE JOURNAL OF CATALYSIS 卷: 31 期: 7 页: 759-764 DOI: 10.1016/S1872-2067(09)60085-1 出版年: JUL 2010 | 被引频次: 1 (来自 Web of Science) | 引用的参考文献: 22 [ 查看 Related Records ] 引证关系图 | 摘要: The catalytic performance of Al-MCM-41 containing 5-35 wt% H3PO4 was studied for the