Bidentate N,O-prolinate ruthenium benzylidene catalyst highly active in RCM of disubstituted dienes

The synthesis of a bidentate N,O-prolinate ruthenium benzylidene from commercially available starting materials and its activity in ring-closing metathesis of functionalized disubstituted dienes at 30 °C is disclosed

Consequential life cycle assessment of kraft lignin recovery with chemical recycling

: The recovery of kraft lignin from black liquor allows an increasing of the pulp production of a kraft mill (marginal tonnage) and at the same time provide a valuable material that can be used as energy or chemical feedstock. However, because lignin precipitation is an energy- and material-consuming process, the environmental consequences from a life cycle perspective are under discourse. The aim of this study is to investigate, through the application of consequential life cycle assessment, the potential environmental benefits of kraft lignin recovery and its subsequent use as an energy or chemical feedstock. A newly developed chemical recovery strategy was assessed. The results revealed how the use of lignin as energy feedstock is not environmentally advantageous compared to producing energy directly from the pulp mill's recovery boiler. However, the best results were observed when lignin was used as a chemical feedstock in four applications to replace bitumen, carbon black, phenol, and bisphenol-A

Zeolite-Assisted Lignin-First Fractionation of Lignocellulose: Overcoming Lignin Recondensation through Shape-Selective Catalysis

This is the peer reviewed version of the following article: E. Subbotina, A. Velty, J. S. M. Samec, A. Corma, ChemSusChem 2020, 13, 4528, which has been published in final form at https://doi.org/10.1002/cssc.202000330. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Organosolv pulping releases reactive monomers from both lignin and hemicellulose by the cleavage of weak C-O bonds. These monomers recombine to form undesired polymers through the formation of recalcitrant C-C bonds. Different strategies have been developed to prevent this process by stabilizing the reactive monomers (i.e., lignin-first approaches). To date, all reported approaches rely on the addition of capping agents or metal-catalyzed stabilization reactions, which usually require high pressures of hydrogen gas. Herein, a metal- and additive-free approach is reported that uses zeolites as acid catalysts to convert the reactive monomers into more stable derivatives under organosolv pulping conditions. Experiments with model lignin compounds showed that the recondensation of aldehydes and allylic alcohols produced by the cleavage of beta-O-4 ' bonds was efficiently inhibited by the use of protonic beta zeolite. By applying a zeolite with a preferred pore size, the bimolecular reactions of reactive monomers were effectively inhibited, resulting in stable and valuable monophenolics. The developed methodology was further extended to birch wood to yield monophenolic compounds and value-added products from carbohydrates.This work was supported by the Swedish Energy Agency, Stiftelsen Olle Engkvist Byggm~stare, and the European Union through ERC-AdG-2014-671093-SynCatMatch.Subbotina, E.; Velty, A.; Samec, JSM.; Corma Canós, A. (2020). Zeolite-Assisted Lignin-First Fractionation of Lignocellulose: Overcoming Lignin Recondensation through Shape-Selective Catalysis. ChemSusChem. 13(17):4528-4536. https://doi.org/10.1002/cssc.202000330S452845361317Adler, E. (1977). Lignin chemistry?past, present and future. Wood Science and Technology, 11(3), 169-218. doi:10.1007/bf00365615Galkin, M. V., & Samec, J. S. M. (2016). Lignin Valorization through Catalytic Lignocellulose Fractionation: A Fundamental Platform for the Future Biorefinery. ChemSusChem, 9(13), 1544-1558. doi:10.1002/cssc.201600237Schutyser, W., Renders, T., Van den Bosch, S., Koelewijn, S.-F., Beckham, G. T., & Sels, B. F. (2018). Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading. Chemical Society Reviews, 47(3), 852-908. doi:10.1039/c7cs00566kSun, Z., Fridrich, B., de Santi, A., Elangovan, S., & Barta, K. (2018). Bright Side of Lignin Depolymerization: Toward New Platform Chemicals. Chemical Reviews, 118(2), 614-678. doi:10.1021/acs.chemrev.7b00588Sturgeon, M. R., Kim, S., Lawrence, K., Paton, R. S., Chmely, S. C., Nimlos, M., … Beckham, G. T. (2013). A Mechanistic Investigation of Acid-Catalyzed Cleavage of Aryl-Ether Linkages: Implications for Lignin Depolymerization in Acidic Environments. ACS Sustainable Chemistry & Engineering, 2(3), 472-485. doi:10.1021/sc400384wShuai, L., Amiri, M. T., Questell-Santiago, Y. M., Héroguel, F., Li, Y., Kim, H., … Luterbacher, J. S. (2016). Formaldehyde stabilization facilitates lignin monomer production during biomass depolymerization. Science, 354(6310), 329-333. doi:10.1126/science.aaf7810Questell-Santiago, Y. M., Zambrano-Varela, R., Talebi Amiri, M., & Luterbacher, J. S. (2018). Carbohydrate stabilization extends the kinetic limits of chemical polysaccharide depolymerization. Nature Chemistry, 10(12), 1222-1228. doi:10.1038/s41557-018-0134-4Deuss, P. J., Scott, M., Tran, F., Westwood, N. J., de Vries, J. G., & Barta, K. (2015). Aromatic Monomers by in Situ Conversion of Reactive Intermediates in the Acid-Catalyzed Depolymerization of Lignin. Journal of the American Chemical Society, 137(23), 7456-7467. doi:10.1021/jacs.5b03693Lahive, C. W., Deuss, P. J., Lancefield, C. S., Sun, Z., Cordes, D. B., Young, C. M., … Barta, K. (2016). Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent. Journal of the American Chemical Society, 138(28), 8900-8911. doi:10.1021/jacs.6b04144Barta, K., & Ford, P. C. (2014). Catalytic Conversion of Nonfood Woody Biomass Solids to Organic Liquids. Accounts of Chemical Research, 47(5), 1503-1512. doi:10.1021/ar4002894Deuss, P. J., Lahive, C. W., Lancefield, C. S., Westwood, N. J., Kamer, P. C. J., Barta, K., & de Vries, J. G. (2016). Metal Triflates for the Production of Aromatics from Lignin. ChemSusChem, 9(20), 2974-2981. doi:10.1002/cssc.201600831Kaiho, A., Kogo, M., Sakai, R., Saito, K., & Watanabe, T. (2015). In situ trapping of enol intermediates with alcohol during acid-catalysed de-polymerisation of lignin in a nonpolar solvent. Green Chemistry, 17(5), 2780-2783. doi:10.1039/c5gc00130gJastrzebski, R., Constant, S., Lancefield, C. S., Westwood, N. J., Weckhuysen, B. M., & Bruijnincx, P. C. A. (2016). Tandem Catalytic Depolymerization of Lignin by Water-Tolerant Lewis Acids and Rhodium Complexes. ChemSusChem, 9(16), 2074-2079. doi:10.1002/cssc.201600683Zhang, L., Xi, G., Yu, K., Yu, H., & Wang, X. (2017). Furfural production from biomass–derived carbohydrates and lignocellulosic residues via heterogeneous acid catalysts. Industrial Crops and Products, 98, 68-75. doi:10.1016/j.indcrop.2017.01.014Anderson, E. M., Stone, M. L., Katahira, R., Reed, M., Beckham, G. T., & Román-Leshkov, Y. (2017). Flowthrough Reductive Catalytic Fractionation of Biomass. Joule, 1(3), 613-622. doi:10.1016/j.joule.2017.10.004Kumaniaev, I., Subbotina, E., Sävmarker, J., Larhed, M., Galkin, M. V., & Samec, J. S. M. (2017). Lignin depolymerization to monophenolic compounds in a flow-through system. Green Chemistry, 19(24), 5767-5771. doi:10.1039/c7gc02731aVan den Bosch, S., Renders, T., Kennis, S., Koelewijn, S.-F., Van den Bossche, G., Vangeel, T., … Sels, B. F. (2017). Integrating lignin valorization and bio-ethanol production: on the role of Ni-Al2O3catalyst pellets during lignin-first fractionation. Green Chemistry, 19(14), 3313-3326. doi:10.1039/c7gc01324hDusselier, M., Van Wouwe, P., Dewaele, A., Jacobs, P. A., & Sels, B. F. (2015). Shape-selective zeolite catalysis for bioplastics production. Science, 349(6243), 78-80. doi:10.1126/science.aaa7169Zhang, L., Xi, G., Chen, Z., Jiang, D., Yu, H., & Wang, X. (2017). Highly selective conversion of glucose into furfural over modified zeolites. Chemical Engineering Journal, 307, 868-876. doi:10.1016/j.cej.2016.09.001Cui, J., Tan, J., Deng, T., Cui, X., Zhu, Y., & Li, Y. (2016). Conversion of carbohydrates to furfural via selective cleavage of the carbon–carbon bond: the cooperative effects of zeolite and solvent. Green Chemistry, 18(6), 1619-1624. doi:10.1039/c5gc01948

A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy_3)_2Cl_2 Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy_3)Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy_3)Cl_2Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system

A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy_3)_2Cl_2 Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy_3)Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy_3)Cl_2Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system

A combination of experimental and computational methods to study the reactions during a Lignin-First approach

AbstractCurrent pulping technologies only valorize the cellulosic fiber giving total yields from biomass below 50 %. Catalytic fractionation enables valorization of both cellulose, lignin, and, optionally, also the hemicellulose. The process consists of two operations occurring in one pot: (1) solvolysis to separate lignin and hemicellulose from cellulose, and (2) transition metal catalyzed reactions to depolymerize lignin and to stabilized monophenolic products. In this article, new insights into the roles of the solvolysis step as well as the operation of the transition metal catalyst are given. By separating the solvolysis and transition metal catalyzed hydrogen transfer reactions in space and time by applying a flow-through set-up, we have been able to study the solvolysis and transition metal catalyzed reactions separately. Interestingly, the solvolysis generates a high amount of monophenolic compounds by pealing off the end groups from the lignin polymer and the main role of the transition metal catalyst is to stabilize these monomers by transfer hydrogenation/hydrogenolysis reactions. The experimental data from the transition metal catalyzed transfer hydrogenation/hydrogenolysis reactions was supported by molecular dynamics simulations using ReaXFF

Intramolecular substitutions of secondary and tertiary alcohols with chirality transfer by an iron (III) catalyst

Optically pure alcohols are abundant in nature and attractive as feedstock for organic synthesis but challenging for further transformation using atom efficient and sustainable methodologies, particularly when there is a desire to conserve the chirality. Usually, substitution of the OH group of stereogenic alcohols with conservation of chirality requires derivatization as part of a complex, stoichiometric procedure. We herein demonstrate that a simple, inexpensive, and environmentally benign iron(III) catalyst promotes the direct intramolecular substitution of enantiomerically enriched secondary and tertiary alcohols with O-, N-, and S-centered nucleophiles to generate valuable 5-membered, 6-membered and aryl-fused 6-membered heterocyclic compounds with chirality transfer and water as the only byproduct. The power of the methodology is demonstrated in the total synthesis of (+)-lentiginosine from D-glucose where iron-catalysis is used in a key step. Adoption of this methodology will contribute towards the transition to sustainable and bio-based processes in the pharmaceutical and agrochemical industries.Peer reviewe

Lignin-first biorefining of Nordic poplar to produce cellulose fibers could displace cotton production on agricultural lands

Here, we show that lignin-first biorefining of poplar can enable the production of dissolving cellulose pulp that can produce regenerated cellulose, which could substitute cotton. These results in turn indicate that agricultural land dedicated to cotton could be reclaimed for food production by extending poplar plantations to produce textile fibers. Based on climate-adapted poplar clones capable of growth on marginal lands in the Nordic region, we estimate an environmentally sustainable annual biomass production of similar to 11 tonnes/ha. At scale, lignin-first biorefining of this poplar could annually generate 2.4 tonnes/ha of dissolving pulp for textiles and 1.1 m(3) biofuels. Life cycle assessment indicates that, relative to cotton production, this approach could substantially reduce water consumption and identifies certain areas for further improvement. Overall, this work highlights a new value chain to reduce the environmental footprint of textiles, chemicals, and biofuels while enabling land reclamation and water savings from cotton back to food production

Uncoupling proteins, dietary fat and the metabolic syndrome

There has been intense interest in defining the functions of UCP2 and UCP3 during the nine years since the cloning of these UCP1 homologues. Current data suggest that both UCP2 and UCP3 proteins share some features with UCP1, such as the ability to reduce mitochondrial membrane potential, but they also have distinctly different physiological roles. Human genetic studies consistently demonstrate the effect of UCP2 alleles on type-2 diabetes. Less clear is whether UCP2 alleles influence body weight or body mass index (BMI) with many studies showing a positive effect while others do not. There is strong evidence that both UCP2 and UCP3 protect against mitochondrial oxidative damage by reducing the production of reactive oxygen species. The evidence that UCP2 protein is a negative regulator of insulin secretion by pancreatic β-cells is also strong: increased UCP2 decreases glucose stimulated insulin secretion ultimately leading to β-cell dysfunction. UCP2 is also neuroprotective, reducing oxidative stress in neurons. UCP3 may also transport fatty acids out of mitochondria thereby protecting the mitochondria from fatty acid anions or peroxides. Current data suggest that UCP2 plays a role in the metabolic syndrome through down-regulation of insulin secretion and development of type-2 diabetes. However, UCP2 may protect against atherosclerosis through reduction of oxidative stress and both UCP2 and UCP3 may protect against obesity. Thus, these UCP1 homologues may both contribute to and protect from the markers of the metabolic syndrome