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

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 role for suppressed thermogenesis favoring catch-up fat in the pathophysiology of catch-up growth

Catch-up growth is a risk factor for later obesity, type 2 diabetes, and cardiovascular diseases. We show here that after growth arrest by semistarvation, rats refed the same amount of a low-fat diet as controls show 1) lower energy expenditure due to diminished thermogenesis that favors accelerated fat deposition or catch-up fat and 2) normal glucose tolerance but higher plasma insulin after a glucose load at a time point when their body fat and plasma free fatty acids (FFAs) have not exceeded those of controls. Isocaloric refeeding on a high-fat diet resulted in even lower energy expenditure and thermogenesis and increased fat deposition and led to even higher plasma insulin and elevated plasma glucose after a glucose load. Stepwise regression analysis showed that plasma insulin and insulin-to-glucose ratio after the glucose load are predicted by variations in efficiency of energy use (i.e., in thermogenesis) rather than by the absolute amount of body fat or plasma FFAs. These studies suggest that suppression of thermogenesis per se may have a primary role in the development of hyperinsulinemia and insulin resistance during catch-up growth and underscore a role for suppressed thermogenesis directed specifically at catch-up fat in the link between catch-up growth and chronic metabolic diseases

SS Ari: a shallow-contact close binary system

Two CCD epochs of light minimum and a complete R light curve of SS Ari are presented. The light curve obtained in 2007 was analyzed with the 2003 version of the W-D code. It is shown that SS Ari is a shallow contact binary system with a mass ratio $q=3.25$ and a degree of contact factor f=9.4(\pm0.8%). A period investigation based on all available data shows that there may exist two distinct solutions about the assumed third body. One, assuming eccentric orbit of the third body and constant orbital period of the eclipsing pair results in a massive third body with $M_3=1.73M_{\odot}$ and P_3=87.0$yr. On the contrary, assuming continuous period changes of the eclipsing pair the orbital period of tertiary is 37.75yr and its mass is about$0.278M_{\odot}$. Both of the cases suggest the presence of an unseen third component in the system.Comment: 28 pages, 9 figures and 5 table

Pseudo-single crystal electrochemistry on polycrystalline electrodes : visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction

The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale

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

Solvation free energy profile of the SCN- ion across the water-1,2-dichloroethane liquid/liquid interface. A computer simulation study

The solvation free energy profile of a single SCN- ion is calculated across the water-1,2-dichloroethane liquid/liquid interface at 298 K by the constraint force method. The obtained results show that the free energy cost of transferring the ion from the aqueous to the organic phase is about 70 kJ/mol, The free energy profile shows a small but clear well at the aqueous side of the interface, in the subsurface region of the water phase, indicating the ability of the SCN- ion to be adsorbed in the close vicinity of the interface. Upon entrance of the SCN- ion to the organic phase a coextraction of the water molecules of its first hydration shell occurs. Accordingly, when it is located at the boundary of the two phases the SCN- ion prefers orientations in which its bulky S atom is located at the aqueous side, and the small N atom, together with its first hydration shell, at the organic side of the interface