Modification of lignin structure by amine group introduction
2011 (English)In: Int. Symp. Wood, Fiber Pulping Chem. - Proc., ISWFPC, 2011, 298-303 p.Conference paper (Refereed)
Amination of lignin conducted simply by Mannich reaction is an important mean for lignin structural and value upgradation. However, there is a lack of powerful analysis for quantification of the amine groups introduced and at the meantime for supplement of structural information about e.g. binding positions and side reactions etc. Various types of NMR analysis have thus been performed for the analysis of Mannich reaction products from lignin model, 4-hydroxy-3-methoxyacetophenone (HMAP), and from industrial spruce Kraft lignin. As revealed by NMRs, the reaction was very selective at C-5 position of guaiacyl lignin units and complete under acidic conditions with 11-fold amounts of reagents of piperidine (PIP) or dimethylamine (DMA) and formaldehyde over HMAP. No side reactions took place at the aromatic structure. For industrial lignin, 13.5 (by PIP) and 15 (by DMA) nitrogen atoms were introduced per 100 aromatic rings. Using other analytical methods, the aminated lignin was found with higher molecular weights, reaching Mp of 5.06kDa from the original 3.92kDa by DMA modification, and with a sharp increased solubility especially in acetic acid aqueous solution, 31.2 mg/ml after DMA modification. A preceding phenolation of the lignin resulted in a 70% increase of available aromatic rings and an introduction of 56 amine groups over 100 original aromatic rings after Mannich reaction by using DMA, which caused increases of molecular weights to 5.11kDa (Mp) and of solubility in acetic acid aqueous solution up to 77.2 mg/mL. Potential applications of these modified lignins of high values include many applications in different fields such as surfactant chemicals, polycationic materials and slow released fertilizers etc.
Place, publisher, year, edition, pages
2011. 298-303 p.
, 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 1
Aminated lignin, Mannich reaction, NMR, Phenolation, Solubility, 4-Hydroxy-3-methoxyacetophenone, Acidic conditions, Amine groups, Analytical method, Aromatic rings, Aromatic structures, Dimethylamines, Guaiacyl lignin units, Kraft lignin, Lignin models, Lignin structure, Mannich reactions, Modified lignins, Nitrogen atom, NMR analysis, Potential applications, Side reactions, Structural information, Upgradation, Acetic acid, Amination, Aromatization, Lignin, Molecular weight, Nuclear magnetic resonance, Organic compounds, pH, Phenols, Solutions, Surface active agents, Wood, Lignins, Reaction Kinetics
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-150223ScopusID: 2-s2.0-84862927873OAI: oai:DiVA.org:kth-150223DiVA: diva2:742282
16th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC, 8 June 2011 through 10 June 2011, Tianjin
QC 201409012014-09-012014-09-012014-09-01Bibliographically approved