Solvent Influence on Selectivity in α-Pinene Oxide Isomerization Using MoO3-Modified Zeolite BETA

Eva Vrbková,Eliška Vyskočilová,Libor Červený,Miloslav Lhotka

doi:10.3390/catal10111244

Eva Vrbková, Eliška Vyskočilová + Show 2 more

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https://doi.org/10.3390/catal10111244

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Abstract

Natural source turpentine is an available source of α-pinene oxide. This compound’s value is especially given by the possibility of producing important compounds campholenic aldehyde and trans-carveol. In this work, we would like to present the usage of MoO3-modified zeolite BETA in α-pinene oxide isomerization concerning campholenic aldehyde and trans-carveol formation using a wide range of solvents. Catalyst calcination temperature also influenced the reaction course (selectivity to desired compounds and reaction rate). MoO3-zeolite BETA was prepared by the wet impregnation method and characterized by different techniques. The use of polar aprotic solvents had the most positive effect on the reaction course. Solvent basicity and polarity considerably influenced the reaction rate and selectivity to particular products. The combination of high basicity and the high polarity was the most suitable for the studied reaction from the reaction rate point of view. Selectivity to campholenic aldehyde and trans-carveol was the most influenced by solvent basicity. Higher solvent basicity caused the preferential formation of trans–carveol, influence on selectivity to campholenic aldehyde formation was the opposite. The described catalyst may be used for α-pinene oxide rearrangement to both desired products dependently on the used solvent. Molybdenum offers an exciting alternative for previously described modifications of zeolites for this reaction.

Highlights

Introduction αPinene oxide is an important compound, which does not occur in nature itself
The most valued compounds, which can be obtained from this compound isomerization, are campholenic aldehyde and trans-carveol
We demonstrated solvent influence on α-pinene oxide (APO) isomerization using molybdenum modified zeolite BETA

Summary

Introduction

Pinene oxide is an important compound, which does not occur in nature itself. Simple oxidation of α-pinene—a natural compound abundant present in renewable source turpentine (obtained from biomass processing) [1]—leads to α-pinene oxide. The most valued compounds, which can be obtained from this compound isomerization, are campholenic aldehyde and trans-carveol. Campholenic aldehyde, which itself possesses by a gently woody smell, can be further used to synthesize fragrances with sandalwood scent (e.g., sandalore, Figure 1), trans-carveol can be part of fragrances bearing caraway and spearmint scent. Catalysts 2020, 10, x FOR PEER REVIEW. Several biological activities (antimicrobial, anticancer [2,3]) accompany these substances. Several biological activities anticancer [2,3]) preparation accompanyusing thesehomogeneous substances

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