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 vapor phase alkylation of phenol with tert-butyl alcohol (TBA) from 383 to 493 K.4-Tert-butyl phenol was produced as the main product with moderate selectivity. The product distribution depends on the reaction temperature, number of acid sites, and the Bronsted to Lewis sites ratios. A lower molar ratio of reactants (TBA/phenol = 2) and a higher space velocity facilitated the production of 4-tert-butyl phenol. The influence of various parameters such as temperature, reactant feed molar ratio, feed rate, and time on stream were investigated for conversion yield and product selectivity.
Ab initio study of the selective alkylation of m-cresol with tert-butanol catalyzed by SO3H-functionalized ionic liquids
| 作者: Zhou, JX (Zhou, Jinxia)1,2; Liu, XM (Liu, Xiumei)1; Zhang, SG (Zhang, Shuguang)2; Mao, JB (Mao, Jingbo)2; Guo, XW (Guo, Xinwen)1
| 来源出版物: CATALYSIS TODAY 卷: 149 期: 1-2 页: 232-237 DOI: 10.1016/j.cattod.2009.07.089 出版年: JAN 15 2010
| 被引频次: 0 (来自 Web of Science)
引用的参考文献: 16 [ 查看 Related Records ] 引证关系图
| 会议: International Symposium on Catalysis 会议地点: Seoul, SOUTH KOREA 会议日期: JUL 21-24, 2008
| 摘要: Our previous work showed that for catalytic alkylation of m-cresol with tert-butanol (TBA) SO3H-functionalized ionic liquids exhibited several characteristic advantages over conventional catalysts. This work investigated the reaction mechanism of the alkylation of m-cresol with tert-butanol catalyzed by the SO3H-functionalized ionic liquid (IL) through quantum chemical calculation in combination with the experimental Studies. The experimental results showed that 2-tert-butyl-5-methyl phenol (2-TBC), 4-tert-butyl-3-methyl phenol (4-TBC) and tert-butyl-m-cresol ether (TBMCE) products were all primary products, while 2,6-di-tert-butyl-3-methyl phenol (2,6-DTBC) was a secondary product The calculation results indicated that the selectivities of the products depended on the fundamental natures of the reactive sites, including the orbital overlap, the...
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