Oxidation of a lignin model disyringyl dimer with nitrogen dioxide (NO2) in the presence of air and N-hydroxysuccinimide led to C1-C#x3B1;cleavage with the formation of approximately equal amounts of 2,6-dimethoxy-p-benzoquinone (DMBQ) and glyceraldehyde-2-syringyl ether type structures. The result indicates that only the phenolic end syringyl units of a lignin polymer will be converted to DMBQ upon treatment with the current NO2reaction conditions. Internal (non-phenolic) lignin units, bonded by #x3B2;-O-4 linkages, will resist oxidation.
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