Photoyellowing behavior of non-phenolic lignin models representative of end groups and beta-ether structures
Artikel i vetenskaplig tidskrift, 2004

Lignin model compounds representative of etherified end groups [(E)-3-(3,4-dimethoxyphenyl)-2-propenl-ol (1), (E)-3-(3,4-dimethoxyphenyl) propenal (2)] and βethers, [1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxy- phenoxy)-1-propanone (3), erythiro-1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)- 1,3-propanediol (4)] have been applied to filter paper and subjected to accelerated photoaging with UV/VIS-light. The changes in optical properties were monitored. In case of all the models, the brightness decreased and the b*-value increased as a result of irradiation, which shows that they are sensitive to light simulating sunlight behind window-glass. In the case of the end group models, the photo-products identified were veratraldehyde and veratric acid together with the Z-isomers of the starting materials. In the case of the cinnamyl alcohol 1, photo-oxidation to the cinnamaldehyde 2 was observed. The irradiation of the αt-carbonylic βether 3 resulted in the homolytic cleavage of the CβO bond and a recombination that led to a β-5 dimer [1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-hydroxy-3-methoxyphenyl)- 1-propanone] and a β-1 dimer [1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(4- hydroxy-3-methoxyphenyl)-l-propanone]. The monomeric products veratraldehyde, vanillin, acetoveratrone, and 1-(3,4-dimethoxyphenyl)-3-hydroxy-l-propanone were also formed. The only photoproduct conclusively identified in experiments with the arylglycerol-β-aryl ether 4 was veratraldehyde and most of the starting material was unaffected by the irradiation. The addition of a photosensitizer (acetoveratrone) to this type of model prior to irradiation resulted in some increase in discoloration.

yellowing

NMR

photochemistry

structure

lignin models

lignin

Författare

Jim Parkås

Chalmers

Magnus Paulsson

Chalmers

Stora Enso Research Centre

Shiming Li

Chalmers, Institutionen för kemiteknik och miljövetenskap, Skogsindustriell kemiteknik

Knut Lundquist

Chalmers, Institutionen för kemiteknik och miljövetenskap, Skogsindustriell kemiteknik

U. Westermark

Luleå tekniska universitet

Nordic Pulp and Paper Research Journal

0283-2631 (ISSN)

Vol. 19 2 146-154

Drivkrafter

Hållbar utveckling

Fundament

Grundläggande vetenskaper

Ämneskategorier

Kemiteknik

Kemi

Styrkeområden

Materialvetenskap

Mer information

Senast uppdaterat

2018-09-10