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Solvent-free chromium catalyzed aerobic oxidation of biomass-based alkenes as a route to valuable fragrance compounds

Paper ID Volume ID Publish Year Pages File Format Full-Text
41442 45889 2011 7 PDF Available
Title
Solvent-free chromium catalyzed aerobic oxidation of biomass-based alkenes as a route to valuable fragrance compounds
Abstract

Chromium containing mesoporous molecular sieves MCM-41 were shown to be an efficient heterogeneous catalyst for the liquid-phase aerobic oxidation of various monoterpenic alkenes under mild solvent-free conditions. The material was prepared through a direct hydrothermal method and characterized by ICP-AES, N2 adsorption–desorption, TEM, XRD, SAXS, and H2-TPR techniques. Characterizations suggest that chromium introduced in MCM-41 is essentially incorporated in the silica framework, with no extraframework chromium oxides being detected. Various oxygenated monoterpenoids important for the flavor and fragrance industry were obtained with high combined selectivities (75–92%) at 30–40% substrate conversions. The oxidation of β-pinene led almost exclusively to allylic mono-oxygenated derivatives, whereas limonene and α-pinene gave both epoxides and allylic oxidation products. The catalyst undergoes no metal leaching and can be easily recovered and re-used. A silica-included chromium catalyst prepared through a conventional sol–gel method showed activity comparable with that of Cr-MCM-41; however, selectivity was much lower.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (140 K)Download as PowerPoint slideHighlights► Cr-MCM-41 was prepared by a direct hydrothermal method using a surfactant. ► Cr–SiO2/sol–gel was prepared by a conventional sol–gel method. ► The oxidation of limonene and α-pinene gives epoxides and allylic oxidation products. ► β-Pinene gives allylic mono-oxygenated derivatives in up to 92% combined selectivity. ► Cr-MCM-41 showed much higher selectivity than Cr–SiO2/sol–gel in these reactions.

Keywords
Monoterpenes; Oxidation; Oxygen; Chromium catalysts; Mesoporous molecular sieves
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 399, Issues 1–2, 31 May 2011, Pages 172–178
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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Full-text PDF Download
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