|
|||||
|
|
Synthesis of coumarin derivatives in a microfluidic flow system employing the Pechmann condensation: A case study |
|
| Authors: | Ling-Kang Liu Jhao-Hong Deng Yang-Ming Guo |
| Affiliation: | 1. Institute of Chemistry, Academia Sinica, Taipei, Taiwan;2. Institute of Chemistry, Academia Sinica, Taipei, Taiwan Department of Applied Chemistry, Chinese Culture University, Taipei, Taiwan;3. Department of Applied Chemistry, Chinese Culture University, Taipei, Taiwan |
| Abstract: | 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. H2SO4(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/H2O extraction of the product mixture, where the H2O 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 H2SO4 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. |
| Keywords: | catalyst recovery and reuse Coumarin derivatives ionic liquid microfluidic flow reactions Pechmann condensation |