1,721,077 research outputs found
Die Chemie und der Wurm: Caenorhabditis elegans als Plattform für das Zusammenführen von chemischer und biologischer Forschung
No full textDer Einsatz von Nanoskiving zur Fertigung von Nanostrukturen fr elektronische und optische Anwendungen
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Recent Advances in the targeted Functionalization of Lignin
No full textA targeted use and functionalisation of lignin obtained within biomass refinery processes is still to be improved in order to obtain a wider variety of possibilities that can give rise to the application of lignin in high value applications. The oxidative functionalisation, and thus valorisation of lignin, is a very promising way to go, since it holds the possibilities to yield highly functionalised, monomeric or oligomeric products that can serve as starting materials for further valorisation in the chemical and pharmaceutical industries.
Gaining a profound knowledge about the structure of lignin, being able to analyse structural features, separate lignins according to structural features, and understanding the mechanisms that guide the reactions leading to oxidative derivatisation and enzymatic functionalisation of lignin samples from different renewable sources are key requirements for developing protocols for a defined oxidative valorisation of lignin. In our presentation, we wish to revisit, and set into context, some important achievements in the field of oxidatively upgrading lignin and add new findings concerning the use of non-classical lingo-cellulosic enzymes in lignin valorisation protocols.
Apart from enzymatic transformations, we will present the formation of a wide variety of functional lignins via a simple strategy. This strategy is applicable also to the formation of block-copolymers in which lignin is covalently linked to both other natural polymers and synthetic polymers
Experimental and Theoretical Investigations on the Equilibriums of Epimers of Complexed Lithiated Benzyl Carbamates
No full textENVR 396 - Tannins structural characterization by quantitative 31P-NMR analysis: An unprecedented tool for tannins analysis, screening, and quality control
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CELL 187 - Correlating structural features of lignin with physical properties: Toward a descriptive-predictive database
No full textThe efficient use of all available biomass components is of utmost interest with respect to a sustainable use of renewable resources. Lignin as the second most-abundant component in forest biomass is, however, currently not exploited to its fullest potential. The straight-forward use is impeded by several lowdowns on the molecular level: i) the structures of isolated lignins differ depending on the isolation process; ii) the size of poly- and oligomeric structures are very different among different lignins; iii) the distribution and or abundance of basic building blocks and bonding motifs differ among different lignins. Current research efforts are aiming at a better understanding of both, the structural features of isolated lignins, and the physical properties of isolated lignins, fractionated isolated lignins, and chemically modified lignins. These important research activities – detailed structural characterisation and determination of physical properties – should be closely linked, however, for different types of lignins, to arrive at a more fundamental understanding of lignin: a descriptive model for lignin that would also allow predictions of physical properties based on structural features, and vice versa, would drastically simplify any work related to the valorisation of lignin.
In an all-encompassing approach for the characterisation of lignin, physical data such a glass transition temperature, decomposition temperature, etc. that were obtained for a collection of representative types of lignins as well as fractions thereof, were correlated systematically with detailed structural features and molecular mass key data to form a database that can serve as quick reference for the selection of the right lignin type for a envisaged application. Current efforts are aimed at adding functionalised lignins to this database
Advanced structural analysis of lignin - a strategy for improving functionalisation of lignin
No full textLignin is the second most abundant of all the natural polymers that comprise plant biomass. Its challenging structural and chemical properties still present the main obstacle to its widespread use in chemical, pharmaceutical, and medicinal applications. An rather exact knowledge about i) its chemical features in terms quantitative data for the intrinsic functional groups, ii) its structural features in terms of quantitative data regarding interunit bonding motifs and non-phenolic end-groups, as well as iii) its key molecular mass data, namely the number average molecular weight Mn, the weight average molecular weight Mw, and the polydispersity PD, are the prerequisites for achieving reasonable tailored chemical functionalisation for targeted high value-added applications.
As part of our on-going efforts to develop reliable and easy-to-adopt protocols and general data analysis schemes for the characterisation of the plant-derived polyphenols lignins and tannins, as preparation of their chemical modification for targeted applications, we systematically evaluated methods widely used for lignin characterisation, focussing on elements that normally give rise to misunderstanding, misinterpreting and false results.
We compared different advanced quantitative NMR techniques (QQ-HSQC, HSQC0, 31P NMR) for the analysis of lignins, and quantified often under-estimated error sources in the chromatographic analyses, such as i) the nature of calibration of the analytical set-up, the influence of the nature of the detector used for recording, and the effect on the molecular masses caused by solubility-enhancing functionalisation methods used in lignin chromatography. By combining and correlating the different analyses, we obtain unprecedented levels of accuracy in the structural and chemical characterisation of lignins and tannins
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