No abstract

The quantification of lignin functional groups constitutes an essential step for effective assessment of lignin transformation. A new, fast, economical, and simple method without the use of harmful solvents is presented for lignin phenolic hydroxyl group quantification. The new method is based on simultaneous conductometric and acid–base titration based on pH in aqueous medium, and it provides, in a single measurement, phenolic hydroxyl and carboxyl group quantification. The new method provokes an inherent error due to the phenolic structure of lignin. This error should be 10% maximum for the low amount of condensed structures in the analyzed technical lignin samples. Four industrial lignin samples (PB-Protobind lignin, ORG-Organolsolv lignin, KF-Kraft lignin, IND-Indulin lignin) have been analyzed using the new method, and the results were compared with six classical methods (UV, 31P NMR, 1H NMR, 13C NMR, Folin Ciocalteu, and aminolysis). The results showed good statistical correlation of the new method with the UV and 31P NMR, the most significant methods, with coefficients of variation among 6 and 14%. Moreover, the carboxyl content results presented high accuracy with a traditional method as tetra-n-butylammonium hydroxide (TnBAH) potentiometric titration.

No abstract

Please cite this article as: Espino-Pérez, E., Gilbert, R. G., Domenek, S., Brochier-Salon, M. C., Belgacem, M. N., and Bras, J.,Nanocomposites with functionalized polysaccharide nanocrystals through aqueous free radical polymerisation promoted by ozonolysis, Carbohydrate Polymers (2015), http://dx.doi.org/10. 1016/j.carbpol.2015.09.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Cellulose nanocrystals (CNC) and starch nanocrystals (SNC) were grafted by ozone-initiated 26 free-radical polymerisation of styrene in a heterogeneous medium. Surface functionalisation 27 was confirmed by infrared spectroscopy, contact angle measurements, and thermogravimetric 28 and elemental analysis. X-ray diffraction and scanning electron microscopy showed that there 29 was no significant change in the morphology or crystallinity of the nanoparticles following 30 ozonolysis. The grafting efficiency, quantified by 13 C NMR, was greater for SNC, with a 31 styrene/anhydroglucose ratio of 1.56 compared to 0.25 for CNC. The thermal stability 32 improved by 100 °C. The contact angles were 97° and 78° following the SNC and CNC 33

No abstract

Complete 1H and 13C assignments for 6‐deoxy‐6‐iodo‐D‐glucose, an analogue of glucose which is transported across the cell membrane, are given. These allowed rotameric populations around the C(5)—C(6) bond to be determined. Comparison with those observed for glucose suggests that the 6‐OH group does not play a major role in glucose transport. Copyright © 2000 John Wiley & Sons, Ltd.

The preparation of cellulose derivatives using green (i.e., environmentally friendly) reagents would improve sustainability and reduce concerns arising from the use of non-green reagents. The objective of this work was to prepare cellobiose carbonate using a green reagent, dimethyl carbonate. The carbonation reaction was carried out in the presence of ethanolic potassium hydroxide solution and dimethyl carbonate for 6 h at a range of temperatures (25-70 °C). A cellobiose derivative was successfully prepared with a recovered yield of more than 70 % and characterized by FTIR and NMR spectroscopy techniques. The presence of a grafted disaccharide with a degree of substitution higher than 2 was determined by (13) C NMR analysis. The spectra of the prepared cellobiose carbonate exhibited peaks that were associated with cellulose molecules (C1 -C6 ) and corresponded to carbonate functions at around 159.4 ppm.

Lignins from kraft and mechanical pulps were isolated before and after oxygen treatment with conventional methods (acidolysis and enzymatic isolation) and with a novel two-step method combining an enzymatic treatment and acidolysis. Results showed that the combined enzymatic hydrolysis-acidolysis made it possible to extract lignin from pulp with a better yield than acidolysis alone and with a higher degree of purity than after enzymatic hydrolysis alone. The lignin samples isolated with the two-step method were analysed by 13 C NMR, 19 F NMR and by gel permeation chromatography. It was shown that the behaviour of mechanical pulp lignin during oxygen treatment was different from that of kraft pulp lignin. Most of these differences could be explained by the lower phenolic content and larger molecular size of the mechanical pulp lignin. As a consequence, oxygen had a poor delignifying effect. Finally, 19 F NMR spectroscopy showed that oxygen could destroy some quinones induced by the alkaline conditions of the O stage.