FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W7674948> ?p ?o ?g. }

• W7674948 abstract "This study deals with the use of selectively 13 C-enriched dehydrogenation polymers (DHPs) as models of lignin in lignocellulosic materials for elucidating the reaction pathways involved in light-induced yellowing. Methods for the synthesis of coniferin, a precursor to lignin and DHP, selectively 13 C-enriched in the aromatic ring (positions 1, 3, 4, and 5) have been developed. The photoyellowing experiments were performed in solid state using UV/VIS-light and the chemical changes were traced using solution and solid state NMR spectroscopy. The results show that unsaturated end groups of the cinnamyl alcohol type are photodegraded under the formation of end groups of the benzaldehyde and benzoic acid types. The findings regarding cinnamaldehyde end groups were, however, not unanimous in the case of photoyellowed DHPs, possibly due to different experimental conditions. Studies of monomeric lignin model compounds of the non-phenolic cinnamyl alcohol and cinnamaldehyde types [( E )-3-(3,4-dimethoxyphenyl)-2-propen-1-ol and ( E )-3-(3,4-dimethoxyphenyl)propenal] indicate that both types of end groups generate color and degradation products during irradiation. Irradiation with UV/VIS-light induces E/Z -isomerization of the starting materials, as well as photo-oxidation of the cinnamyl alcohol to the corresponding cinnamaldehyde. No conclusive evidence of any significant β-ether cleavage was obtained from the experiments, either with CW-DHP (cell wall-dehydrogenation polymer) or with DHP. The relative amount of β-ethers was not extensively changed, although very small amounts of a suggested cleavage product (of the 1-aryl-3-hydroxy-1-propanone type) was indicated in the β- and γ- 13 C-enriched samples. The observed decrease in the relative amount of C α in arylglycerol-β-aryl ether structures, indicated in the difference spectrum ( 13 C-enriched - unenriched) corresponding to α- 13 C-enriched DHP (applied to filter paper, irradiated, and extracted), could be due to changes other than β-ether cleavage. A moderate formation of α-carbonyls occurred, although the exact nature of these structures is unknown, at present. However, studies of dimeric lignin model compounds of the non-phenolic β-ether type, with and without an α-carbonyl group [1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)-1-propanone and erythro -1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol], showed that both models form colored materials upon irradiation. More color was formed in the case of the α-carbonylic model. Apart from monomeric degradation products, dimers of the β-5 and β-1 types were formed during irradiation of the α-carbonylic β-ether model, indicative of a homolytic cleavage of the C β -O bond and recombination of the initially formed radicals (β-5 recombination more favored). In all investigated lignin model compounds, photoproducts indicative of C α -C β cleavage ( e.g. , structures of the benzaldehyde type) were formed. No conclusive evidence for the formation of quinones was obtained." @default.
• W7674948 created "2016-06-24" @default.
• W7674948 creator A5014069576 @default.
• W7674948 date "2003-01-01" @default.
• W7674948 modified "2023-09-26" @default.
• W7674948 title "13C-Enriched Dehydrogenation Polymers Used for Studying Light-Induced Yellowing of Lignocellulosic Materials" @default.
• W7674948 hasPublicationYear "2003" @default.
• W7674948 type Work @default.
• W7674948 sameAs 7674948 @default.
• W7674948 citedByCount "0" @default.
• W7674948 crossrefType "journal-article" @default.
• W7674948 hasAuthorship W7674948A5014069576 @default.
• W7674948 hasConcept C119889771 @default.
• W7674948 hasConcept C161790260 @default.
• W7674948 hasConcept C178790620 @default.
• W7674948 hasConcept C185592680 @default.
• W7674948 hasConcept C2777435628 @default.
• W7674948 hasConcept C2779692420 @default.
• W7674948 hasConcept C2780407432 @default.
• W7674948 hasConcept C2780440420 @default.
• W7674948 hasConcept C2780526948 @default.
• W7674948 hasConcept C2781052789 @default.
• W7674948 hasConceptScore W7674948C119889771 @default.
• W7674948 hasConceptScore W7674948C161790260 @default.
• W7674948 hasConceptScore W7674948C178790620 @default.
• W7674948 hasConceptScore W7674948C185592680 @default.
• W7674948 hasConceptScore W7674948C2777435628 @default.
• W7674948 hasConceptScore W7674948C2779692420 @default.
• W7674948 hasConceptScore W7674948C2780407432 @default.
• W7674948 hasConceptScore W7674948C2780440420 @default.
• W7674948 hasConceptScore W7674948C2780526948 @default.
• W7674948 hasConceptScore W7674948C2781052789 @default.
• W7674948 hasLocation W76749481 @default.
• W7674948 hasOpenAccess W7674948 @default.
• W7674948 hasPrimaryLocation W76749481 @default.
• W7674948 hasRelatedWork W1963615181 @default.
• W7674948 hasRelatedWork W1984352907 @default.
• W7674948 hasRelatedWork W2006371928 @default.
• W7674948 hasRelatedWork W2018466019 @default.
• W7674948 hasRelatedWork W2049419982 @default.
• W7674948 hasRelatedWork W2051139047 @default.
• W7674948 hasRelatedWork W2058234135 @default.
• W7674948 hasRelatedWork W2060361395 @default.
• W7674948 hasRelatedWork W2065148246 @default.
• W7674948 hasRelatedWork W2079340468 @default.
• W7674948 hasRelatedWork W2081166910 @default.
• W7674948 hasRelatedWork W2091509406 @default.
• W7674948 hasRelatedWork W2105496421 @default.
• W7674948 hasRelatedWork W2130817794 @default.
• W7674948 hasRelatedWork W2135546662 @default.
• W7674948 hasRelatedWork W2147966360 @default.
• W7674948 hasRelatedWork W2521842348 @default.
• W7674948 hasRelatedWork W2952968283 @default.
• W7674948 hasRelatedWork W3015206154 @default.
• W7674948 hasRelatedWork W3108807740 @default.
• W7674948 isParatext "false" @default.
• W7674948 isRetracted "false" @default.
• W7674948 magId "7674948" @default.
• W7674948 workType "article" @default.