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Combined Experimental and Theoretical Study of the Synthesis of 5,7-Dihydroxy-4-methylcoumarin via a Pechmann Condensation in the Presence of UiO-66-SO 3 H Catalysts.
- Source :
-
ACS omega [ACS Omega] 2023 Nov 30; Vol. 8 (49), pp. 46904-46913. Date of Electronic Publication: 2023 Nov 30 (Print Publication: 2023). - Publication Year :
- 2023
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Abstract
- An efficient synthesis of 5,7-dihydroxy-4-methylcoumarin from phloroglucinol with ethyl acetoacetate in the UiO-66-SO <subscript>3</subscript> H metal-organic framework is reported. The potential of UiO-66-SO <subscript>3</subscript> H as a solid catalyst was determined through optimized-condition experiments and quantum molecular calculations. The optimal conditions for the synthesis of 5,7-dihydroxy-4-methylcoumarin with UiO-66-SO <subscript>3</subscript> H were as follows: phloroglucinol/ethyl acetoacetate molar ratio = 1:1.6, reaction time = 4 h, and temperature = 140 °C, for which the reaction yield reached 66.0%. The reusability of UiO-66-SO <subscript>3</subscript> H catalysts for Pechmann condensation was examined. The activation energy of the reaction occurring on a sulfonic group of the UiO-66-SO <subscript>3</subscript> H catalyst was 12.6 kcal/mol, which was significantly lower than 22.6 kcal/mol of the same reaction on the UiO-66 catalyst. To comprehend the reaction mechanism, density functional theory with the ONIOM approach was applied for the synthesis of coumarin on the UiO-66-SO <subscript>3</subscript> H and UiO-66 clusters. A possible reaction mechanism was proposed involving three steps: a trans-esterification step, an intramolecular hydroxyalkylation step, and a dehydration step. The rate-determining step was suggested to be the first step which acquired an activation energy of 15.7 and 29.5 kcal/mol, respectively. Information from this study can be used as guidelines to develop more efficient catalytic metal-organic frameworks for various organic syntheses.<br />Competing Interests: The authors declare no competing financial interest.<br /> (© 2023 The Authors. Published by American Chemical Society.)
Details
- Language :
- English
- ISSN :
- 2470-1343
- Volume :
- 8
- Issue :
- 49
- Database :
- MEDLINE
- Journal :
- ACS omega
- Publication Type :
- Academic Journal
- Accession number :
- 38107951
- Full Text :
- https://doi.org/10.1021/acsomega.3c06624