Contents of α-O-4 and β-O-4 Bonds in Native Lignin and Isolated Lignin Preparations

Evstigneyev, Edward I.; Kalugina, Aleksandra V.; Ivanov, А. Yu.; Vasilyev, Aleksander V.

doi:10.1080/02773813.2017.1297832

Cited by 23 publications

(6 citation statements)

References 28 publications

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“…The influence of various fractionation techniques (i.e., catalytic oxidative and reductive methods) on lignin structure and morphology is currently focused in numerous studies [ 28 , 29 ]. Thus, HSQC spectra of aromatic (dC/dH 100–135/5.5–8.5) and aliphatic (dC/dH 50–90/2.5–6.0) regions of lignin sample were discussed in detail by Chen and Vasilyev [ 30 , 31 ]. Analogue to these studies, we used the HSQC NMR spectroscopy to study differences in lignin structure obtained from various Miscanthus X giganteus genotypes.…”

Section: Lignin Availability and Structurementioning

confidence: 99%

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

et al. 2018

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Renewable resources are gaining increasing interest as a source for environmentally benign biomaterials, such as drug encapsulation/release compounds, and scaffolds for tissue engineering in regenerative medicine. Being the second largest naturally abundant polymer, the interest in lignin valorization for biomedical utilization is rapidly growing. Depending on its resource and isolation procedure, lignin shows specific antioxidant and antimicrobial activity. Today, efforts in research and industry are directed toward lignin utilization as a renewable macromolecular building block for the preparation of polymeric drug encapsulation and scaffold materials. Within the last five years, remarkable progress has been made in isolation, functionalization and modification of lignin and lignin-derived compounds. However, the literature so far mainly focuses lignin-derived fuels, lubricants and resins. The purpose of this review is to summarize the current state of the art and to highlight the most important results in the field of lignin-based materials for potential use in biomedicine (reported in 2014–2018). Special focus is placed on lignin-derived nanomaterials for drug encapsulation and release as well as lignin hybrid materials used as scaffolds for guided bone regeneration in stem cell-based therapies.

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Section: Lignin Availability and Structurementioning

confidence: 99%

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

et al. 2018

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“…Isolation of lignin preparations from spruce wood and their analysis were described in the previous work. [39] Analytical characteristics of the lignin preparations are presented in Table 1.…”

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confidence: 99%

Solid-State ¹³C CP/MAS NMR for Alkyl-O-Aryl Bond Determination in Lignin Preparations

Evstigneyev

Mazur

Kalugina

et al. 2018

Journal of Wood Chemistry and Technology

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Several lignin preparations (Freudenberg lignin, Björkman lignin and Pepper lignin), technical lignins (soda, soda-AQ, Kraft, Kraft-AQ and hydrolysis), dimeric lignin model compounds and different polysaccharides (galactoglucomannan, arabinogalactan, xylan and arabinan) were analysed by solid-state 13 C CP/MAS NMR. Signals' assignment in solid-state NMR lignin spectra was performed on the basis ofthe conducted studies and literature data.It wasestablished that there exists strong linear correlation (r = 0.985) between Alkyl-O-Aryl inter-unit bonds' content in lignin and integral signals intensity in NMR spectra in the range of chemical shifts of 96-68 ppm. The integral signals intensity was measured in respect to the reference integral signals in the range of chemicalshifts of 162-102 ppm, which is typical for aromatic carbon atoms.To eliminate the effect from the carbohydrates contained in lignin, the correction factor for calculation was determined, i.e. 0.67% of the area of integration for each percent of carbohydrates. It was shown that the solid-state 13 C CP/MAS NMR method allowed to determine Alkyl-O-Aryl bonds' content in both soluble and insoluble lignin preparations, and also to quantify methoxyl groups' content in soluble preparations.

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“…There are two types of interunit linkages (C–C and C–O) in the β- O -4 model compound ( 1 ) (Scheme ). Increasing oxygen in β- O -4 ether linkages might decrease the π–π interaction between rings, and consequently the etheric bonds (C–O) have lower thermal stability. ,,,− Additionally, supplementing oxidation with metal oxides (e.g., VPP or VPP/HZSM-5) shows a pronounced effect in improving the cleavage of β- O -4 ether linkages. Thus, substrate ( 1 ) is broken efficiently at mild conditions via step 1 in Scheme , resulting in the formation of guaiacol ( 2 ) and ketone ( 3 ) as the main products of softwood lignin fragmentation .…”

Section: Resultsmentioning

confidence: 99%

Gas–Solid Oxidation of Unwashed Lignin to Carboxylic Acids

et al. 2020

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The availability and multifunctionality of lignin makes it a desirable, renewable alternative to petroleum for specialty and bulk chemicals. However, recovering lignin from black liquor is expensive, thus lowering its prospect as a raw material source. Direct conversion of unwashed lignin (UL) to chemicals eliminates unit operations and reaction steps, which makes it a more likely feedstock. We compared the selective oxidation of lignin and UL to produce carboxylic acids over vanadium pyrophosphate (VPP), HZSM-5 zeolite, and VPP/HZSM-5 catalysts at atmospheric pressure and varying temperature (from 140 to 650 °C), steam concentration (from 0 to 20%), and oxygen (from 0 to 15.5%). The main acids produced were formic acid, acetic acid, and malonic acid. VPP/HZSM-5 produced 5% more acids with UL compared to treated lignin. The catalytic reaction network comprises both anaerobic and aerobic pathways for oxidation-based valorization of free phenolic guaiacylglycerol-β-guaiacyl ether (GG) and non-phenolic veratrylglycerol β-guaiacyl ether (VG) model lignin compounds. The three main reaction types include selective catalytic oxidative depolymerization with interunit bond breakage (e.g., alkyl–O–aryl bonds), alkyl side chain modification (e.g., Cα–OH to CαO ketone), and aromatic ring oxidation and ring opening to produce benzoquinones and dicarboxylic acids.

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Contents of α-O-4 and β-O-4 Bonds in Native Lignin and Isolated Lignin Preparations

Cited by 23 publications

References 28 publications

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

Solid-State ¹³C CP/MAS NMR for Alkyl-O-Aryl Bond Determination in Lignin Preparations

Gas–Solid Oxidation of Unwashed Lignin to Carboxylic Acids

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Contents of α-O-4 and β-O-4 Bonds in Native Lignin and Isolated Lignin Preparations

Cited by 23 publications

References 28 publications

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

Lignin-Derived Biomaterials for Drug Release and Tissue Engineering

Solid-State 13C CP/MAS NMR for Alkyl-O-Aryl Bond Determination in Lignin Preparations

Gas–Solid Oxidation of Unwashed Lignin to Carboxylic Acids

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Product

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Solid-State ¹³C CP/MAS NMR for Alkyl-O-Aryl Bond Determination in Lignin Preparations