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Updated: Jun 10, 2026

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)
Published on: January 17, 2020
Mechanistic insight into low-temperature alkylation of thiophene with styrene over zeolites MCM-22 and β
Xiaopan Li1, Sensen Shang2,3, Chenyu Liu1
1Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization, Tianjin University of Science and Technology, Tianjin, People's Republic of China.
Abstract:
Friedel-Crafts alkylation reactions are generally accepted to proceed by an electrophilic aromatic substitution (SEAr) mechanism. Here, we observed that MCM-22 exhibited a high activity in the alkylation of thiophene with styrene at temperatures near ambient, while β was almost inactive. Three species were identified in the adsorption of thiophene on HMCM-22 and Hβ: the hydrogen-bonded thiophene, the protonated thiophene, and the thiophene oligomers. Styrene was chemically adsorbed on the two zeolites through its vinyl group. The infrared studies of the consecutive adsorption of thiophene and styrene on MCM-22 and β reveal that the major difference between the thiophene species on the two zeolites was the disappearance of the protonated thiophene on MCM-22. These results indicate that the reaction over MCM-22 occurs by the attack of a protonated thiophene molecule on the side chain of styrene that chemically adsorbed on the zeolite but not the conventional SEAr mechanism.
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