| 1. |
- Dawange, Monali, et al.
(författare)
-
Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds : Route to Aryl Ketones
- 2015
-
Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 7:3, s. 401-404
-
Tidskriftsartikel (refereegranskat)abstract
- A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.
|
|
| 2. |
- De Santi, Alessandra, et al.
(författare)
-
Lignin‐First Fractionation of Softwood Lignocellulose Using a Mild Dimethyl Carbonate and Ethylene Glycol Organosolv Process
- 2020
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:17, s. 4468-4477
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 3. |
- Francois, Camille, et al.
(författare)
-
Diglycidylether of iso-eugenol : a suitable lignin-derived synthon for epoxy thermoset applications
- 2016
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 6:73, s. 68732-68738
-
Tidskriftsartikel (refereegranskat)abstract
- A novel lignin-based synthon, diglycidylether of iso-eugenol (DGE-isoEu) is used as a prepolymer for the preparation of thermosetting resins. DGE-isoEu is synthesized in a two-step procedure with a satisfactory yield from bio-based iso-eugenol (isoEu, 2-methoxy-4-(1-propenyl)phenol) catalytically fragmented from lignin in an organosolv process. DGE-isoEu was fully characterized by NMR, MS and FTIR. Curing of the DGE-isoEu monomer has then been investigated in the presence of several carboxylic acid derivatives hardeners. The thermal and mechanical properties of each material were recorded showing, in particular, a high T-g and instantaneous modulus values in the range of 78-120 degrees C and 4.6-5.5 GPa, respectively. The lignin derived new materials give very attractive thermo-mechanical properties comparable to that of common BPA-containing epoxy resins.
|
|
| 4. |
|
|
| 5. |
- Frasca, Serena, et al.
(författare)
-
Toward Biomass-Based Organic Electronics : Continuous Flow Synthesis and Electropolymerization of N-Substituted Pyrroles
- 2024
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 9:12, s. 13852-13859
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Frasca, Serena, et al.
(författare)
-
Toward biomass-based organic electronics: Continuous flow synthesis and electropolymerization of N-substituted polypyrroles
- 2023
-
Ingår i: ACS Spring meeting 2023. - Indianapolis.
-
Konferensbidrag (refereegranskat)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.
|
|
| 7. |
- Galkin, Maxim, et al.
(författare)
-
Depolymerisation of lignin in biomass
- 2022
-
Patent (populärvet., debatt m.m.)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.
|
|
| 8. |
|
|
| 9. |
- Galkin, Maxim
(författare)
-
From stabilization strategies to tailor-made lignin macromolecules and oligomers for materials
- 2021
-
Ingår i: CURRENT OPINION IN GREEN AND SUSTAINABLE CHEMISTRY. - : Elsevier. - 2452-2236. ; 28
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 10. |
- Galkin, Maxim, 1986-
(författare)
-
Palladium-catalyzed lignin valorization : Towards a lignin-based biorefinery
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work described in this thesis focuses on the cleavage of the β-O-4′ bond, which is the most abundant interunit linkage in the lignin polymer.In the first part, three methods based on palladium catalysis have been developed and their applicability has been verified using lignin model compounds. A transfer hydrogenolysis of the β-O-4′ bond using formic acid as a mild hydrogen donor together with a base. An aerobic oxidation of the benzylic alcohol motif in the β-O-4′ linkage to generate a key intermediate in the cleavage reaction was performed. A redox neutral cleavage of the β-O-4′ bond was accomplished in which no stoichiometric reducing or oxidizing agents were added.In the second part of the thesis, a mechanistic study is presented. The corresponding ketone from a dehydrogenation reaction of the benzylic alcohol motif was identified to be the key intermediate. This ketone and its enol tautomer was found to be responsible for the β-O-4′ bond cleavage reaction under the employed reaction conditions.In the final part of this thesis, the methodologies have been applied to native lignin. The depolymerization reaction was combined with organosolv pulping. This approach was successful, and together with cellulose and hemicellulose, propenyl aryls were generated in excellent yields directly from wood. In this transformation, the lignin derived molecules have been reduced by an endogenous hydrogen donor from the wood.
|
|
