Über Essigsäure‐Lignin.

Oxidative degradation of wood. 6. Identification of carboxylic aromatic products of alkaline nitrobenzene oxidation

“…It is pertinent to note that a 0.3% yield of 5-carboxyvanillin was found in the alkaline nitrobenzene oxidation of eugenol, thereby indicating that condensation and subsequent oxidation may occur at the 6 position of 4-substituted guaiacols (Pew, 1955). Decarboxylation of this compound to give vanillin (Leopold, 1950; Freudenberg and Plankenhorn, 1947) may also occur to a small extent.…”

A Lignin-Carbohydrate Complex in Wood A Review of the Literature

“…This acetic acid lignin, which is soluble in acetic acid, not only contains combined acetyl but also contains combined carbohydrate. Freudenberg (45) reported that a spruce acetic acid lignin, prepared using magnesium chloride äs catalyst, contained 11% hexosan which could be removed by hydrolysis with sulphuric acid. Bell and Wright (10) showed that birch acetic acid lignin, prepared by retluxing with acetic acid alone for one hundred hours, also contained combined carbohydrate which could be spü't off by refluxing with 95% formic acid for eighteen hours.…”