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Synthesis of coumarin derivatives in a microfluidic flow system employing the Pechmann condensation: A case study
Author(s) -
Liu LingKang,
Deng JhaoHong,
Guo YangMing
Publication year - 2020
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.202000371
Subject(s) - chemistry , catalysis , coumarin , condensation , ionic liquid , condensation reaction , extraction (chemistry) , organic chemistry , combinatorial chemistry , physics , thermodynamics
For the synthesis of coumarin derivatives using the Pechmann condensation scheme, an acidic ionic liquid catalyst, abbreviated as [EBsImH][HSO 4 ] , was prepared from the ring opening of 1,4‐butanesultone by 1‐ethylimidazole, followed by the addition of 1 equiv. H 2 SO 4 ( c ). The [EBsImH][HSO 4 ] ‐catalyzed Pechmann condensation reactions proceeded smoothly in a batch setup, with recyclable [EBsImH][HSO 4 ] showing great catalytic activity. The acidic ionic liquid catalyst [EBsImH][HSO 4 ] was recovered from EtOAc/H 2 O extraction of the product mixture, where the H 2 O layer was worked up and dried for reuse in consecutive runs of the Pechmann condensation reactions, maintaining >85% conversion for four times. The catalytic reactions were also carried out in a microfluidic flow setup. The flow parameters, the reactant molar amounts, and the additional H 2 SO 4 as a modifying acid catalyst were optimized in the current case study. A minimum conversion rate of 2.8 g/hr of coumarin derivatives was demonstrated.