Sevilla, Spain
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Liebner F.,Konrad Lorenz Str. 24 | Four G.,Konrad Lorenz Str. 24 | De La Rosa Arranz J.M.,Estrada Nacional 10 | Hilseher A.,Emil Ramann StraRe 2 | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

15N CPMAS NMR and XPS spectra of 15N labelled ammonoxidised technical lign ins, methoxyhydroquinone and 2,5- dihydroxy-[1,4]benzoquinone were very similar, indicative for a reaction sequence proceeding via a common key intermediate. Therefore, (substituted) 2,5-diamino-[1,4]benzoquinones are proposed to be key intermediates of the chemical alteration of ligneous materials caused by ammonia or amines in the presence of oxygen. 2, 5-Diamino-[1,4]benzoquinones are vinylogous am ides which are highly stabilised by tautomery and resonance. Both ammonoxidised methoxyhydroquinone and 2,5-dihydroxy- [1,4]benzoquinone were confirmed to bind CO 2. 2,5-Dihydroxy- [1,4]benzoquinone was furthermore shown to react in alkaline medium with CO 2 to C 2-C 4 monoacids, oxoacids and diacids. Subjecting the ammonoxidised lignins to pot experiments resulted in a surprisingly fast formation of am ides. During the first weeks at least apart of the Nd passes through the microbial biomass stage. The harvested plants showed an N enrichment caused by the amendment. Respiration experiments revealed comparable CO 2 production rates in soil incubated with and without Nlign ins, possibly because microbial activity competed with CO 2 for the available N groups. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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