THE PROPERTIES OF SYRINGYL, GUAIACYL AND P-HYDROXYPHENYL ARTIFICIAL LIGNINS

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Abstract
Artificial lignins have been produced on potato parenchyma. The methoxyl-free lignin and 4-hydroxy-3-methoxy (guaiacyl) lignins could be estimated by the sulphuric acid method but the 4-hydroxy-3,5-dimethoxy (syringyl) lignins could not. Permanganate oxidation of isolated p-coumaric lignin gave 4-hydroxybenzoic acid, 4-hydroxyisophthalic acid and small amounts of hydroxytrimesic acid and 4-hydroxyphthalic acid. Ferulic lignin gave vanillic acid and 5-carboxyvanillic acid and also small amounts of 4-hydroxybenzoic acid and dehydrodivanillic acid. The sinapic lignin gave traces of syringic acid and of 4-hydroxybenzoic acid. The [rho]-coumaric lignin is a highly condensed polymer. The ferulic lignin is partly uncondensed and partly condensed through the 5-position like gymno-sperm lignin. The sinapic lignin shows no evidence of condensation and is probably an ether-linked polymer.