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Fast and reliable quantification of lignin reactivity via reaction with dimethylamine and formaldehyde (Mannich reaction)
RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden.
RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia.ORCID-id: 0000-0002-4858-7352
RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden.ORCID-id: 0000-0002-4521-1122
2017 (engelsk)Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, nr 1, s. 27-34Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The influence of pH on the Mannich reaction (amino alkylation in the presence of formaldehyde) has been analyzed by liquid chromatography-mass spectrometry (LC-MS) with vanillin (VA) as a model compound and a purified softwood kraft lignin (SKL) as a substrate. The reaction products of VA were studied at pH 5, 7, and 9 at 60°C for 4 h. The Mannich adduct and side reaction products with methylene bridge were found at both pH 7 and 9, while only di-substituted by-products were observed at pH 5. Nitrogen contents determined from blank runs were substantial at pH 5 and negligible at pH 7. In VA or SKL, the resulting N-contents at pH 7 corresponded to a 76 or 62 mol% of the theory, respectively, i.e. based on the available C5 positions in phenolic guaiacyl units (G-units). In the case of SKL, 31P-NMR analysis confirmed a 77% conversion of all phenolic G-units into their C5 substituted derivatives. The Mannich reaction should be performed on lignin at pH 7 for 1 h to suppress unwanted side reactions, which could be observed by LC-MS under other pH conditions. The reaction is suitable for fast and reliable determination of reactive C5-positions in lignin by multiplication of the N-content of the reaction products with a factor of 1.6.

sted, utgiver, år, opplag, sider
2017. Vol. 71, nr 1, s. 27-34
Emneord [en]
Amination, Chemical reactions, Formaldehyde, Liquid chromatography, Mass spectrometry, Nitrogen, Organic polymers, Reaction products, Reactivity (nuclear)
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Identifikatorer
URN: urn:nbn:se:ri:diva-28194DOI: 10.1515/hf-2016-0054Scopus ID: 2-s2.0-85008709552OAI: oai:DiVA.org:ri-28194DiVA, id: diva2:1074885
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Tilgjengelig fra: 2017-02-16 Laget: 2017-02-16 Sist oppdatert: 2023-03-27bibliografisk kontrollert

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