Über die Isolierung, Struktur und Biosynthese des Lignins
ABSTRACT The various ways in which lignin may be isolated are briefly described with special emphasis on those methods which allow
of a separation under mild conditions. Although the problem of the isolation of the bulk of lignin in a chemically unaltered
state is not completely solved as yet, encouraging results have recently been obtained by grinding wood powder in a non-swelling
solvent and extracting the lignin with dioxan („Björkman-lignin”). The analytical composition of this product is given.
The question of the structure of lignin is treated in thelight of our present knowledge and is based on the results of numerous
investigations. Only those having immediate connection with the structural problems could be taken into account. The work
has been divided into two parts: one dealing with the determination of the substituents on the aromatic nuclei (following
oxidative and reductive degradations), the other giving information on the structural features of the three carbon atoms in
the side chains. In connection with the latter, the most important lignin reactions are briefly discussed as those reactions
take place in the non-aromatic portion of lignin.
The probable-pathway of lignin biosynthesis is outlined. The first part describes the stages which result in the transformation
of carbohydrates into molecules having a phenyl-propane skeleton (C6−C3.) The second part deals with the laboratory transformation of the latter into an artificial lignin by enzymatic oxidation
reactions and polymerization reactions.