Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the emerging elegant procedures to obtain specific aromatic products rely on the lignin substrate having a high content of the readily cleavable β-O-4 linkage as present in the native lignin structure. This provides a miss-match with typical technical lignins that are highly degraded and therefore are low in β-O-4 linkages. Therefore, the extraction yields, and the quality of the obtained lignin are of utmost importance to access new lignin valorization pathways. In this manuscript, a simple protocol is presented to obtain lignins with high β-O-4 content by relatively mild ethanol extraction that can be applied to different lignocellulose sources. Furthermore, analysis procedures to determine the quality of the lignins are presented together with a depolymerization protocol that yields specific phenolic 2-arylmethyl-1,3-dioxolanes, which can be used to evaluate the obtained lignins. The presented results demonstrate the link between lignin quality and potential for the lignins to be depolymerized into specific monomeric aromatic chemicals. Overall, the extraction and depolymerization demonstrates a trade-off between the lignin extraction yield and the retention of the native aryl-ether structure and thus the potential of the lignin to be used as the substrate for the production of chemicals for higher-value applications. Video Link The video component of this article can be found at https://www.jove.com/video/58575/ 17. This also has precedence in organosolv extraction of lignin, which is a popular method to fractionate lignin. Many variations of this process exist, with the methods employing different temperatures, acid content, extraction times and solvents. Here, the extraction severity has a direct impact on the obtained lignin structure and thus its suitability for further valorization 19,20,21. For example, organosolv lignin produced by the ethanol based Alcell process, operated for 5 years at demonstration scale, had relatively low amount of β-O-4 linkages left as it was operated at relatively high

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the emerging elegant procedures to obtain specific aromatic products rely on the lignin substrate having a high content of the readily cleavable β-O-4 linkage as present in the native lignin structure. This provides a miss-match with typical technical lignins that are highly degraded and therefore are low in β-O-4 linkages. Therefore, the extraction yields, and the quality of the obtained lignin are of utmost importance to access new lignin valorization pathways. In this manuscript, a simple protocol is presented to obtain lignins with high β-O-4 content by relatively mild ethanol extraction that can be applied to different lignocellulose sources. Furthermore, analysis procedures to determine the quality of the lignins are presented together with a depolymerization protocol that yields specific phenolic 2-arylmethyl-1,3-dioxolanes, which can be used to evaluate the obtained lignins. The presented results demonstrate the link between lignin quality and potential for the lignins to be depolymerized into specific monomeric aromatic chemicals. Overall, the extraction and depolymerization demonstrates a trade-off between the lignin extraction yield and the retention of the native aryl-ether structure and thus the potential of the lignin to be used as the substrate for the production of chemicals for higher-value applications.

Uncalibrated digital radiographs used in multicenter trials hinder quantitative measures such as articular step and ulnar variance. This investigation tested the reliability of alternative measures of ulnar variance that are scaled to the length of the capitate. A sample of 30 sets of radiographs from patients enrolled in a prospective study of operative treatment of fractures of the distal radius were blinded and randomized. Five observers measured the ulnar variance (UV) and longitudinal length of the capitate (CH) on two separate occasions with greater than 2 weeks between measurements. During each measurement session, the observers made the measurements on both a calibrated and a noncalibrated workstation. The ratio of the ulnar variance to the length of capitate was calculated (UV/CH ratio). Paired t tests were used to compare two rounds of measurements for both methods. Intra-and interobserver reliability was assessed by the Pearson product-moment correlation coefficients. The ratios were compared using analysis of variance with a Bonferroni correction. The intraobserver reliability was excellent for each of the three variables (UV, CH, UV/CH ratio) for each workstation. The interobserver reliability of the UV/CH ratios obtained for each workstation was moderate to excellent as judged by the Pearson correlations between observers. The BlandAltman method indicated a mean difference in UV/CH between calibrated and uncalibrated measurement techniques of 0.002 with limits of agreement of −0.11 to 0.11. Measurements of ulnar variance that are scaled to the length of the capitate may be useful measures of deformity in studies that utilize uncalibrated digital radiographs.

The iridium catalyzed transfer vinylation of bio‐based polyols and of other alcohols and phenols with interesting structural motifs was accomplished with vinyl acetate in 2‐MeTHF as a green solvent. The optimized synthetic procedure has as main advantages the use of catalytic instead of stoichiometric amounts of base and high selectivities towards the formation of bis‐vinyl ethers as a result of the suppression of the acetal formation reaction that typically occurs in the vinylation of diols. In addition, the thermodynamically preferred transesterification reaction leading to the acetate esters and bis‐esters was completely suppressed. DFT calculations revealed an iridium‐acetate complex as the active catalytic species and they disclosed the importance of the carbonyl group of vinyl acetate for the formation of a six‐membered cyclic intermediate.

Polymers are involved in countless products ranging from high-tech materials used in areo-space industry, car parts, electronics to simple consumer goods such as clothing, sports gear, carpets, and various packing materials. As a result, humankind currently produces a previously unmatched amount of plastic waste. A lot of this waste is currently dumped in landfills or "mismanaged". In order to counter-act the pollution of the environment as well as to conserve natural resources several strategies have been proposed and developed for the recycling of polymeric materials depolymerization and mechanical recycling being the most applied. Both approaches have in common that it is very difficult for them to be cost competitive with the production of the virgin polymers. A solution to this dilemma could be "chemical upcycling". In this approach a polymer is converted to a higher value new material. In the case of polyesters, we could show that in the presence of a homogenous ruthenium catalyst and Lewis acids polyesters can be hydrogenated to polyether polyols. The type of Lewis acid and its ratio with respect to the ruthenium were proven to be crucial. Based on mechanistic investigations it was shown that this reaction proceeds via a tandem hydrogenation/etherification process. The obtained polyether polyols are in the right molecular weight range for the use in adhesives.

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