Abstract
In this study, acidolysis of benzyl phenyl ether (BPE), being a representative lignin model compound with the α-O-4 linkage, was examined in γ-valerolactone (GVL) and a GVL/water mixture, each time acidified with sulfuric acid. The product distribution was strongly affected by water used as a cosolvent, which was found to be advantageous by inhibiting the formation of larger structures and introducing reactive OH groups instead. The experimental results indicate the GVL/water ratio as an important parameter to attain an optimal hydrolytic α-ether bond cleavage. Differences between the organosolv lignins (molecular weight distribution, OH group content, and structural features with reaction time), isolated under moderate reaction conditions, supported the findings obtained using BPE. A beneficial effect of the added water is reflected in the higher aliphatic OH group content and less intact structure. Analysis of the reaction mechanism represents an initial step toward kinetics and structure–activity correlation of biorefining industrial resources.
Highlights
Environmental issues regarding climate change and the looming depletion of fossil fuels are the main driving forces encouraging us to transform into a biobased society
While the mechanism of initial lignin depolymerization during organosolv pulping with alcohols had been extensively studied, the chemistry of lignin conversions during the GVL-based pulping process remains unclear
Sturgeon et al showed the rate of the β-O-4 cleavage strongly depends on the presence of side groups, explaining why the observed rate of acidolysis can differ between model compounds and biomassderived lignin
Summary
Environmental issues regarding climate change and the looming depletion of fossil fuels are the main driving forces encouraging us to transform into a biobased society This can be achieved by developing new, alternative, and sustainable procedures of producing replacements for petroleum-based products. Lignocellulosic (LC) biomass has been recognized as a suitable renewable material with a high potential for the conversion into various chemicals[1] as well as precursors for polymer synthesis.[2] Lignin is one of the major components of LC biomass It has an aromatic, three-dimensional, highly functionalized network and has been a subject of numerous studies on producing chemicals, especially bioaromatics.[3,4,5]. It could eventually be tailored within fractionation depending on the type of the selected depolymerization/upgrading process.[6,7,8] In general, the content of β-O-4 bonds in lignin is one of the key Received: August 19, 2020 Revised: October 12, 2020 Published: November 13, 2020
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