Modified polystyrene anion exchange resins with long chain alkyl groups to enhance the aldolization reaction selectivity

Authors:  Jiexiang Wang, Qiang Wang, Yu Deng, Yunhua Li, Bing H. Chen, Ruyun Zhang

Abstract:
The aldolization of formaldehyde and acetone to form 4-hydroxy-2-butanone over anion exchange resins with and without modifications is investigated in this work. Attempts such as surfactants addition and Soxhlet extraction are taken aiming to improve the aldolization selectivity thus the product yield. Subsequently, resins grafted long alkyl chains intrigue us for its steric hindrance effect and the synergic effect of weak and strong basic sites. Two types of modifications are carried out (1) one long alkyl chain on the copolymer tertiary amine via Menshutkin N-alkylation reaction; (2) two long alkyl chains: one on polystyrene aromatic ring through Friedel–Crafts alkylation under the circumstances of tertiary amine and the other on the copolymer tertiary amine using the Menshutkin N-alkylation reaction. The reaction results indicate that the yield for 4-hydroxy-2-butanone can be increased from 44.3% to around 50% for the resin with one long alkyl chain (the first case), while this can achieve up to 71.3% for the resin with two long alkyl chains.

Keywords:
Solid base
Aldol condensation
Anion exchange resin
4-Hydroxy-2-butanone

Published in: Applied catalysis A: General  (Volume 452, Pages 1-222, 15 February 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Modified polystyrene anion exchange resins with long chain alkyl groups to enhance the aldolization reaction selectivity

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