| 1. |
- De Santi, Alessandra, et al.
(author)
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Lignin‐First Fractionation of Softwood Lignocellulose Using a Mild Dimethyl Carbonate and Ethylene Glycol Organosolv Process
- 2020
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:17, s. 4468-4477
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Journal article (peer-reviewed)abstract
- A mild lignin-first acidolysis process (140 °C, 40 min) was developed using the benign solvent dimethyl carbonate (DMC) and ethylene glycol (EG) as a stabilization agent/solvent to produce a high yield of aromatic monophenols directly from softwood lignocellulose (pine, spruce, cedar, and Douglas fir) with a depolymerization efficiency of 77–98 %. Under the optimized conditions (140 °C, 40 min, 400 wt % EG and 2 wt % H2SO4 to pinewood), up to 9 wt % of the aromatic monophenol was produced, reaching a degree of delignification in pinewood of 77 %. Cellulose was also preserved, as evidenced by a 85 % glucose yield after enzymatic digestion. An in-depth analysis of the depolymerization oil was conducted by using GC-MS, HPLC, 2 D-NMR, and size-exclusion chromatography, which provided structural insights into lignin-derived dimers and oligomers and the composition of the sugars and derived molecules. Mass balance evaluation was performed.
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| 2. |
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| 3. |
- Frasca, Serena, et al.
(author)
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Toward Biomass-Based Organic Electronics : Continuous Flow Synthesis and Electropolymerization of N-Substituted Pyrroles
- 2024
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 9:12, s. 13852-13859
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Journal article (peer-reviewed)abstract
- Pyrroles are foundational building blocks in a wide array of disciplines, including chemistry, pharmaceuticals, and materials science. Currently sourced from nonrenewable fossil sources, there is a strive to explore alternative and sustainable synthetic pathways to pyrroles utilizing renewable feedstocks. The utilization of biomass resources presents a compelling solution, particularly given that several key bulk and fine chemicals already originate from biomass. For instance, 2,5-dimethoxytetrahydrofuran and aniline are promising candidates for biomass-based chemical production. In this study, we present an innovative approach for synthesizing N-substituted pyrroles by modifying the Clauson-Kaas protocol, starting from 2,5-dimethoxytetrahydrofuran as the precursor. The developed methodology offers the advantage of producing pyrroles under mild reaction conditions with the potential for catalyst-free reactions depending upon the structural features of the substrate. We devised protocols suitable for both continuous flow and batch reactions, enabling the conversion of a wide range of anilines and sulfonamides into their respective N-substituted pyrroles with good to excellent yields. Moreover, we demonstrate the feasibility of depositing thin films of the corresponding polymers onto electrodes through in situ electropolymerization. This innovative application showcases the potential for sustainable, biomass-based organic electronics, thus, paving the way for environmentally friendly advancements in this field.
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| 4. |
- Frasca, Serena, et al.
(author)
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Toward biomass-based organic electronics: Continuous flow synthesis and electropolymerization of N-substituted polypyrroles
- 2023
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In: ACS Spring meeting 2023. - Indianapolis.
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Conference paper (peer-reviewed)abstract
- Pyrroles are important building blocks in many areas of chemistry, pharmaceuticals and materials. Pyrroles are currently fossil-based and transition to renewable alternatives demands new synthetic pathways. The use of biomass is a very attractive option for more sustainable solutions and several bulk and fine chemical are already produced from biomass. 2,5-Dimethoxytetrahydrofuran is an example of fine chemical derived from carbohydrate fraction of biomass. Here we report the synthesis of N-substituted pyrroles through a modified Clauson-Kass protocol starting from 2,5-dimethoxytetrahydrofuran. The proposed method allows to obtain pyrroles under mild reaction conditions and it can be performed catalyst-free. The protocol works both in continuous flow and under batch conditions.. A wide range of anilines and sulphonamides are transformed to corresponding N-substituted pyrroles in good to excellent yields. Conductive films are achieved through electropolymerization and they show distinct redox activity. Current efforts entail the application of the material in sensors or energy storage devices. The proposed method opens the pathway to sustainable biomass-based organic electronics.
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| 5. |
- Galkin, Maxim, et al.
(author)
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Depolymerisation of lignin in biomass
- 2022
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Patent (pop. science, debate, etc.)abstract
- A method of obtaining depolymerized lignin from biomass using a transition metal catalyst and a solvent mixture of organic solvent and water. The invention further relates to a composition obtainable by the method and the production of fuel.
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| 6. |
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| 7. |
- Galkin, Maxim
(author)
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From stabilization strategies to tailor-made lignin macromolecules and oligomers for materials
- 2021
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In: CURRENT OPINION IN GREEN AND SUSTAINABLE CHEMISTRY. - : Elsevier. - 2452-2236. ; 28
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Journal article (peer-reviewed)abstract
- Lignocellulose is a renewable and sustainable resource. It includes terrestrial plants and part of nonedible waste streams of current industries. This raw material is an alternative carbon source for fossils. Lignin from lignocellulosic biomass is undervalorized. This aromatic biomacromolecule that is used as a fuel offers many striking properties such as high thermal stability, biodegradability, UV-blocking, antioxidant, and antimicrobial activities. Recent advances in biomass fractionation provide tailoring of lignin properties in-situ. Outlined innovative methods should ease lignin upgrading toward advanced engineered materials at no extra refining steps, minimizing the use of harmful chemicals and maximizing the biomass utilization.
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| 8. |
- Kumaniaev, Ivan, et al.
(author)
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A combination of experimental and computational methods to study the reactions during a Lignin-First approach
- 2020
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In: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 0033-4545 .- 1365-3075. ; 92:4, s. 631-639
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Journal article (peer-reviewed)abstract
- Current pulping technologies only valorize the cellulosic fiber giving total yields from biomass below 50 %. Catalytic fractionation enables valorization of both cellulose, lignin, and, optionally, also the hemicellulose. The process consists of two operations occurring in one pot: (1) solvolysis to separate lignin and hemicellulose from cellulose, and (2) transition metal catalyzed reactions to depolymerize lignin and to stabilized monophenolic products. In this article, new insights into the roles of the solvolysis step as well as the operation of the transition metal catalyst are given. By separating the solvolysis and transition metal catalyzed hydrogen transfer reactions in space and time by applying a flow-through set-up, we have been able to study the solvolysis and transition metal catalyzed reactions separately. Interestingly, the solvolysis generates a high amount of monophenolic compounds by pealing off the end groups from the lignin polymer and the main role of the transition metal catalyst is to stabilize these monomers by transfer hydrogenation/hydrogenolysis reactions. The experimental data from the transition metal catalyzed transfer hydrogenation/hydrogenolysis reactions was supported by molecular dynamics simulations using ReaXFF.
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| 9. |
- Questell-Santiago, Ydna M., et al.
(author)
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Stabilization strategies in biomass depolymerization using chemical functionalization
- 2020
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In: Nature Reviews Chemistry. - : Springer Science and Business Media LLC. - 2397-3358. ; 4:6, s. 311-330
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Journal article (peer-reviewed)abstract
- A central feature of most lignocellulosic-biomass-valorization strategies is the depolymerization of all its three major constituents: cellulose and hemicellulose to simple sugars, and lignin to phenolic monomers. However, reactive intermediates, generally resulting from dehydration reactions, can participate in undesirable condensation pathways during biomass deconstruction, which have posed fundamental challenges to commercial biomass valorization. Thus, new strategies specifically aim to suppress condensations of reactive intermediates, either avoiding their formation by functionalizing the native structure or intermediates or selectively transforming these intermediates into stable derivatives. These strategies have provided unforeseen upgrading pathways, products and process solutions. In this Review, we outline the molecular driving forces that shape the deconstruction landscape and describe the strategies for chemical functionalization. We then offer an outlook on further developments and the potential of these strategies to sustainably produce renewable-platform chemicals.
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| 10. |
- Wu, Xianyuan, et al.
(author)
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A well-defined diamine from lignin depolymerization mixtures for constructing bio-based polybenzoxazines
- 2021
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In: Chem Catalysis. - : Elsevier. - 2667-1093. ; 1:7, s. 1466-1479
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Journal article (peer-reviewed)abstract
- The demand for high-performance materials is increasing, and most of these materials are petrol based. Therefore, the development of highly efficient and selective catalytic methods that allow access to industrially relevant polymer building blocks from complex biomass depolymerization mixtures is essential. Here, we report on a robust catalytic strategy to obtain the industrially relevant 4,4′-methylenebiscyclohexanamine (MBCA) from lignin oxidation mixtures and its use for constructing fully bio-based polybenzoxazines. The strategy consists of two challenging catalytic steps: 1) the funneling of lignin-derived bisphenol mixtures into 4,4′-methylenebiscyclohexanol (MBC) and 2) the highly selective amination of MBC with ammonia to obtain MBCA. The renewable polybenzoxazines were prepared from MBCA and phenolic lignin platform chemicals. The most promising, cured poly (S-MBCA), shows high glass transition temperature Tg of 315°C, outstanding thermal stability (T10% = 400°C), and good storage modulus (E′25°C = 3.8 GPa), which is competitive with commercial resins.
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