H- and Fe-modified zeolite beta catalysts for preparation of trans-carveol from α-pinene oxide

• Selective isomerisation of -pinene oxide to trans-carveol.
• Selectivity increase during reaction.
• Influence of Lewis and Brønsted acidity on selectivity.
• Minor influence of iron.
• Need for polar basic solvent N,N-dimethylacetamide.

The isomerisation of α-pinene oxide has been intensively investigated for selective preparation of campholenic aldehyde, a compound used in the synthesis of fragrances. Selective preparation of another product of α-pinene oxide rearrangement, trans-carveol, still remains a challenging task. Trans-carveol is a highly valuable compound used in perfume bases, food flavour compositions and as an active pharmaceutical substance in chemoprevention of mammary carcinogenesis.In the present work zeolite beta with different SiO2/Al2O3 molar ratios was modified by iron, characterised and tested per se and in the modified form for trans-carveol preparation from α-pinene oxide. The isomerisation reaction was carried out in a polar basic solvent N,N-dimethylacetamide at 140 °C. The activities and selectivities of the catalysts were correlated with their acid properties and with the iron content.

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