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  • Reactivity of lignin with different composition of aromatic syringyl/guaiacyl structures and erythro/threo side chain structures in β-O-4 type during alkaline delignification: as a basis for the different degradability of hardwood and softwood lignin.

Reactivity of lignin with different composition of aromatic syringyl/guaiacyl structures and erythro/threo side chain structures in β-O-4 type during alkaline delignification: as a basis for the different degradability of hardwood and softwood lignin.

Journal of agricultural and food chemistry (2012-06-15)
Satoko Shimizu, Tomoya Yokoyama, Takuya Akiyama, Yuji Matsumoto
ABSTRACT

The reactivity of lignin during alkaline delignification was quantitatively investigated focusing on the effect of the structural differences between syringyl and guaiacyl aromatic nuclei and between erythro and threo in the side chain of β-O-4 type lignin substructure on the β-O-4 bond cleavage rate. It was known that the ratio of this reaction rate of the erythro to threo isomers of the dimeric β-O-4 type lignin model compound with two guaiacyl aromatic nuclei was ca. 4. However, the presence of a syringyl nucleus strongly influenced the rate, and the ratio of the syringyl type analogue was in the range between 2.7 and 8.0 depending on the reaction temperature. The effect of syringyl nucleus on the enhancement of the reaction rate appeared to be greater when the syringyl nucleus consists of the cleaving ether bond rather than being a member of the carbon framework.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2,6-Dimethoxyphenol, 99%
Sigma-Aldrich
2,6-Dimethoxyphenol, ≥98%, FG
Sigma-Aldrich
Guaiacol, oxidation indicator
Sigma-Aldrich
Guaiacol, natural, ≥99%, FG
Sigma-Aldrich
2,6-Dimethoxyphenol, natural, ≥96%
Supelco
Guaiacol, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
2,6-Dimethoxyphenol, analytical standard