Abstract

Lignin depolymerization represents a promising approach to the sustainable production of aromatic molecules. One potential approach to the stepwise depolymerization of lignin involves oxidation of the benzylic alcohol group in β-O-4 and β-1 linkages, followed by Baeyer–Villiger oxidation (BVO) of the resulting ketones and subsequent ester hydrolysis. Towards this goal, BVO reactions were performed on 2-adamantanone, a series of acetophenone derivatives, and lignin model compounds using a tin beta zeolite/hydrogen peroxide biphasic system. XRD, 119Sn MAS NMR spectroscopy, DRUVS and XPS were used to determine tin speciation in the catalyst, the presence of both framework Sn and extra framework SnO2 being inferred. Conversion of ketones to BVO products was affected by electron donation as well as steric hindrance, 4′-methoxyacetophenone affording the highest yield of ester (81%). As the size and complexity of the ketone increased, excess hydrogen peroxide was typically needed for successful BVO. Yields of ester products derived from β-O-4 and β-1 lignin models were modest due to the formation of polymeric material stemming from direct ring hydroxylation.

Document Type

Article

Publication Date

5-16-2017

Notes/Citation Information

Published in RSC Advances, v. 7, issue 42, p. 25987-25997.

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

Digital Object Identifier (DOI)

https://doi.org/10.1039/C7RA03830E

Funding Information

This material is based on work supported by the National Science Foundation under Cooperative Agreement No. 1355438. Funding from the British Council under the Global Innovation Initiative for the GB3-Net project is also gratefully acknowledged. The single-crystal diffractometer was funded by the NSF (MRI CHE-0319176). Diffuse reflectance UV-Vis spectra were measured at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Related Content

Electronic supplementary information (ESI) available. CCDC 1541264 and 1541265. For ESI and crystallographic data in CIF or other electronic format see DOI:10.1039/c7ra03830e

c7ra03830e1.pdf (2388 kB)
Supplementary information

c7ra03830e2.cif (55 kB)
Crystal structure data

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