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9554958 
Journal Article 
Structural changes of lignin during kraft pulping of Eucalyptus tereticornis 
Bhandari, KS; Bhatnagar, A 
2002 
14 
2 
31-36 
English 
Dioxane lignin from Eucalyptus tereticornis wood and its kraft pulps with kappa number of 44.91 and 26.46 was isolated and subjected to elemental composition, functional groups analysis, IR spectroscopy and alkaline nitrobenzene oxidation studies. Elemental composition of the lignin and empirical formula derived from these values revealed that wood lignin contains lower amount of carbon and higher amount of hydrogen and oxygen as compared to pulp lignin. Methoxyl, alcoholic hydroxyl and phenolic hydroxyl content were decreased on pulping. IR spectroscopic studies also indicated the decrease in methoxyl content. Carbonyl and carboxyl groups were increased on pulping. On alkaline nitrobenzene oxidation of lignin, eight compounds namely p-hydroxy benzoic acid, vanillic acid, syringic acid, p-hydroxy benzaldehyde, vanillin, syringaldehyde, aceto vanillone, acetosyringone were identified by HPLC, quantitatively. The results are discussed in the paper at adequate length.