Elsevier

Journal of Catalysis

Volume 405, January 2022, Pages 288-302
Journal of Catalysis

Synthesis of Florol via Prins cyclization over heterogeneous catalysts

https://doi.org/10.1016/j.jcat.2021.12.008Get rights and content
Under a Creative Commons license
open access

Highlights

  • Prins cyclisation from isovaleraldehyde and isoprenol to tetrahydropyranol.

  • Zeolites with varying acidity and hierarchical materials as catalysts.

  • H-Beta-300 zeolite giving 72% selectivity to the desired product at 99% conversion.

  • The cis/trans ratio of tetrahydropyranols depends on porous structure.

  • Parallel formation of tetrahydropyranol and dihydropyran confirmed by DFT.

Abstract

In this work, several heterogeneous micro- and mesoporous, acidic catalysts were tested for the selective synthesis of Florol®, an industrial product formed via condensation and rehydration starting from isoprenol and isovaleraldehyde in dimethylcarbonate as a solvent. The results showed that a mildly acidic, microporous H-Beta-300 with SiO2/Al2O3 ratio of 300 was the best catalyst, giving 72% selectivity with 99% conversion at 40 °C when using the molar ratio isoprenol to isovaleraldehyde of 1:5. More acidic zeolites gave slightly lower selectivity, while the lowest selectivity (up to 52%) was obtained with mesoporous catalysts exhibiting mild acidity and no strong Brønsted acid sites. Selectivity to pyranols was nearly constant when changing temperature, while a larger excess of isovaleraldehyde promoted formation of tetrahydropyranol. H-Beta-300 catalyst was successfully after calcination at 400 °C. DFT calculations pointed out on the parallel formation of tetrahydro pyranols and dihydropyrans, which are the corresponding dehydration products.

Keywords

Florol
Prins cyclization
Isoprenol
Isovaleraldehyde
Zeolites
Mesoporous materials
DFT

Cited by (0)