Mild and selective etherification of wheat straw lignin and lignin model alcohols by moisture-tolerant zirconium catalysis

Margarita, Cristiana; Francesco, Davide Di; Tuñon, Hernando; Kumaniaev, Ivan; Rada, Carlos Jansson; Lundberg, Helena

doi:10.1039/d2gc04650d

Cited by 10 publications

(8 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Various methods have been proposed for lignin allylation. [39][40][41][43][44][45][46][47] In this work, diallyl carbonate was chosen as an allyl reagent to obtain highly functionalized lignin.…”

Section: Microwave-assisted Allylation Of Fractionated Ligninmentioning

confidence: 99%

“…This has been employed both before and after fractionation, with the aim to produce functional and thermally stable materials using reactions such as epoxidation or esterification. 16,37,38 Allylation reactions have been demonstrated as one versatile route for lignin functionalization [39][40][41][42][43][44][45][46][47] and for producing thermosets. 15,40,41,48 Successful microwave-assisted allylation has been previously studied and demonstrated to work on other compounds than lignin.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microwave‐assisted fractionation and functionalization of technical lignin toward thermoset resins

Truncali,

Ribca,

Yao

et al. 2023

J of Applied Polymer Sci

View full text Add to dashboard Cite

Lignin is the most abundant aromatic biopolymer, with a potential to serve as a building block of rigid and thermally stable bio‐based materials. However, it is still underutilized because of the heterogeneous and not fully understood chemical structure. Here, technical softwood Kraft lignin is refined in to narrow‐dispersity and relatively low molar mass fractions by microwave‐assisted processing, followed by microwave‐assisted allylation and further application in lignin‐based thermosets. This microwave processing is carried out under non‐catalyzed conditions using a low boiling point solvent and elevated pressure. The properties of the retrieved fractions are investigated by 31P‐NMR, heteronuclear single quantum coherence spectroscopy‐NMR, SEC, differential scanning calorimetry, and thermogravimetric analysis. The extraction yield of the selected lignin fraction is around 25%, with the number‐average molar mass (Mn), weight‐average molar mass (Mw), and dispersity (Đ) significantly reduced. The chemically modified lignin is characterized by 31P NMR and FTIR, which provides evidence of the introduction of the allyl moieties. The analyses demonstrate that 90 ± 3% of the hydroxyl groups in fractionated lignin are successfully allylated. Subsequently, the allylated lignin is cross‐linked through thermally induced thiol‐ene chemistry to produce lignin‐based thermosets. The final thermosets exhibit a storage modulus of 4050 ± 60 MPa and a Tg of 105 ± 5°C.

show abstract

Section: Microwave-assisted Allylation Of Fractionated Ligninmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microwave‐assisted fractionation and functionalization of technical lignin toward thermoset resins

Truncali,

Ribca,

Yao

et al. 2023

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…34 These allyl-functional resins were also evaluated as thermoset resins in combination with vegetable oils using metathesis chemistry. 49 Additional reported methods to introduce vinyl groups onto lignin involve using acryloyl chloride, 50 methacryloyl chloride, 51 allyl alcohol, 52 vinyl ethylene carbonate, 53 or a two-step route using ethylene carbonate and acrylic acid. 43 In the present study, softwood Kraft lignin (LignoBoost) is utilized to prepare thiol−ene thermosetting materials with a higher allyl functionality compared to previously studied thermosets based on the same technical lignin.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Molecular Organization on the Properties of Fractionated Lignin-Based Thiol–Ene Thermoset Materials

et al. 2023

View full text Add to dashboard Cite

In this study, the combination of sequential solvent fractionation of technical Kraft lignin was followed by allylation of most OH functionalities to give highly functional thermoset resins. All lignin fractions were highly functionalized on the phenolic (≥95%) and carboxylic acid OH (≥85%) and to a significant extent on the aliphatic OH moieties (between 43 and 75%). The resins were subsequently cross-linked using thiol–ene chemistry. The high amount of allyl functionalities resulted in a high cross-link density. Dynamic mechanical analysis measurements showed that the thioether content, directly related to the allyl content, strongly affects the performance of these thermosets with a glass transition temperature (T g) between 81 and 95 °C and with a storage modulus between 1.9 and 3.8 GPa for all thermosets. The lignin fractions and lignin-based thermosets’ morphology, at the nanoscale, was studied by wide-angle X-ray scattering measurements. Two π–π stacking interactions were observed: sandwich (≈4.1–4.7 Å) and T-shaped (≈5.5–7.2 Å). The introduction of allyl functionalities weakens the T-shaped π–π stacking interactions. A new signal corresponding to a distance of ≈3.5 Å was observed in lignin-based thermosets, which was attributed to a thioether organized structure. At the same time, a lignin superstructure was observed with a distance/size corresponding to 7.9–17.5 Å in all samples.

show abstract

“…[18][19][20][21][22] While stoichiometric derivatization of the hydroxyl group has resulted in selective protocols for various transformations, the strategy is not ideal when considering atom and step economy. To tackle this, catalytic strategies for deoxygenative transformations of non-derivatized alcohols is an area of considerable synthetic interest that encompasses, e. g., dehydrogenative transition metal catalysis, [23][24][25][26] catalytic Mitsunobu protocols, [27,28] carbocationic routes, [29][30][31][32][33] Tsuji-Trost type activation [34] and radical transition metal catalysis (Figure 1, middle). [35,36] While often effective, these catalytic routes are associated with synthetic limitations as a result of their underlying mechanisms; dehydrogenative transformations and catalytic S N 2-type procedures are sensitive to steric hindrance, while ionic and radical routes require substrates that can stabilize the reactive intermediates.…”

Section: Introductionmentioning

confidence: 99%

Electroreductive Deoxygenative C−H and C−C Bond Formation from Non‐Derivatized Alcohols Fueled by Anodic Borohydride Oxidation

Villo,

Lill,

Alsaman

et al. 2023

ChemElectroChem

Self Cite

View full text Add to dashboard Cite

Alcohols are one of the most common organic compound classes among natural and synthetic products. Thus, methods for direct removal of C−OH groups without the need for wasteful pre‐functionalization are of great synthetic interest to unlock the full synthetic potential of the compound class. Herein, electroreductive C−OH bond activation and subsequent deoxygenative C−H and C−C bond formation of benzylic and propargylic alcohols are demonstrated along with mechanistic insights. Experimental and theoretical studies indicate that the reductive C−OH bond cleavage furnishes an open shell intermediate that undergoes a radical‐polar crossover to the corresponding carbanion that subsequently undergoes protonation to furnish alkane products. Furthermore, we demonstrate that the carbanion can be trapped with CO2 to form arylacetic acids. The cathodic transformations are efficiently balanced by the anodic oxidation of sub‐stoichiometric borohydride additives, a strategy that serves as a highly attractive alternative to the use of sacrificial metal anodes.

show abstract

Mild and selective etherification of wheat straw lignin and lignin model alcohols by moisture-tolerant zirconium catalysis

Abstract: The direct etherification of wheat straw lignin and lignin model compounds using alcohols as reagents and zirconocene triflate as water-tolerant Lewis acidic catalyst is herein described. Visual kinetic analysis was...

Cited by 10 publications

References 58 publications

Microwave‐assisted fractionation and functionalization of technical lignin toward thermoset resins

Microwave‐assisted fractionation and functionalization of technical lignin toward thermoset resins

Effect of Molecular Organization on the Properties of Fractionated Lignin-Based Thiol–Ene Thermoset Materials

Electroreductive Deoxygenative C−H and C−C Bond Formation from Non‐Derivatized Alcohols Fueled by Anodic Borohydride Oxidation

Contact Info

Product

Resources

About