A competitive and environmentally sustainable biorefinery should valorize all parts of biomass, including bark. Currently, bark, which constitutes 10 wt% of timber and pulp wood, is burned at a low value. Softwood bark comprises 38% lignin, suggesting that this component could be an important source of valuable aromatic compounds; this lignin also contains substantial amounts of interlinkages with strong C–C bonds, such as β-5 linkages, which are not cleaved during standard depolymerization methods. In contrast to wood lignin which is linear, bark lignin appears to be cyclic, which further hinders depolymerization. Here, we present a method using oxygen to oxidatively depolymerize spruce bark lignin to yield valuable monophenols at 30-fold higher levels than expected from nitrobenzene oxidation. This is an important step in making biorefineries more sustainable and competitive and a new source to green vanillin.

H3PO2-catalyzed intramolecular stereospecific nucleophilic substitution of the hydroxyl group in stereogenic alcohols

Simo Sarkanen opened the discussion of the introductory lecture by Bruce Dale: The supposition that the strength of a national economy is directly related to energy consumption is incomplete. This hypothesis is reminiscent of Marx's suggestion that the value of an article is equivalent to the l

Yiping Luo opened the discussion of the paper by George W. Huber by asking: Did you carry out experiments using different ratios of water and solvent? Why did you choose the ratio 80 : 20? Also, regarding recovery of the lignin, after the experiment at 130 °C, is the structure of the lignin dif

James Clark opened the discussion of the paper by Keith W. Waldron: Regarding the point you made about ethanol, is that because it is flat-lining in terms of growth and demand? New bioethanol plants are being built, are they redundant before they are even complete? Keith Waldron

Biobased diepoxy synthons derived from isoeugenol, eugenol or resorcinol (DGE-isoEu, DGE-Eu and DGER, respectively) have been used as epoxy monomers in replacement of the diglycidyl ether of bisphenol A (DGEBA). Their curing with six different biobased anhydride hardeners leads to fully biobased epoxy thermosets. These materials exhibit interesting thermal and mechanical properties comparable to those obtained with conventional petrosourced DGEBA-based epoxy resins cured in similar conditions. In particular, a high T-g in the range of 90-130 degrees C and instantaneous moduli higher than 4.3 GPa have been recorded. These good performances are very encouraging, making these new fully biobased epoxy thermosets compatible with the usual structural application of epoxy materials. (C) 2017 Academie des sciences. Published by Elsevier Masson SAS.

George Huber opened the discussion of the paper by Xiaoming Huang: Where does the ash go? Does it go into the methanol solution? How much ash ends up on the catalyst versus the methanol versus the cellulose? Is the methanol being converted? Xiaoming Huang answered: We did not tra

Iso-eugenol (isoEu), catalytically fragmented from lignin, is converted into a diglycidylether of iso-eugenol (DGE-isoEu) which leads in the presence of anhydride acids based hardeners to new biobased epoxy thermosets.

The hydroxyl group of enantioenriched benzyl, propargyl, allyl, and alkyl alcohols has been intramolecularly displaced by uncharged O-, N-, and S-centered nucleophiles to yield enantioenriched tetrahydrofuran, pyrrolidine, and tetrahydrothiophene derivatives with phosphinic acid catalysis. The five-membered heterocyclic products are generated in good to excellent yields, with high degree of chirality transfer, and water as the only side-product. Racemization experiments show that phosphinic acid does not promote SN1 reactivity. Density functional theory calculations corroborate a reaction pathway where the phosphinic acid operates as a bifunctional catalyst in the intramolecular substitution reaction. In this mechanism, the acidic proton of the phosphinic acid protonates the hydroxyl group, enhancing the leaving group ability. Simultaneously, the oxo group of phosphinic acid operates as a base abstracting the nucleophilic proton and thus enhancing the nucleophilicity. This reaction will open up new atom efficient techniques that enable alcohols to be used as nucleofuges in substitution reactions in the future.