Renewable Beta-Elemene Based Cyclic Carbonates for the Preparation of Oligo(hydroxyurethane)s

Conversion of β‐elemene into new β‐elemene dicarbonates through epoxidation and halide salt‐catalyzed CO(2) cycloaddition reactions is reported. Step‐growth polyaddition of this dicarbonate to five different, commercial diamines was investigated under neat conditions at 150 °C yielding non‐isocyanate‐based low molecular weight oligo(hydroxyurethane)s with 1.3≤M(n) ≤6.3 kDa and 1.3≤Ð≤2.1, and with glass transition temperatures ranging from −59 to 84 °C. The preparation of one selected polyhydroxyurethane material, obtained in the presence of Jeffamine® D‐2010 was scaled‐up to 43 g. The latter, when combined in a formulation using Irgacure® 2100 and Laromer® LR 9000 allowed the preparation of coatings that were analyzed with several techniques showing the potential of these biobased oligourethanes towards the preparation of commercially relevant materials

Diamination oxydante intramoléculaire d'alcène avec urée en tant que source d'azote (Etude méchanistique à réactions catalysées par Pd et en présence d'halogène)

Résumé français : notice = 7Ko MAXIMUM : résumé trop long empêche la validation : longueur = 1700 caractéresRésumé anglais : idemSTRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Scale-Up Procedure for the Efficient Synthesis of Highly Pure Cyclic Poly(ethylene glycol)

Poly(ethylene glycol) (PEG) is ideally suited for the synthesis of cyclic polymers. The cyclization reaction of PEG via its tosylate intermediate is well established. We improved the cyclization reaction and obtained cyclic raw products in high yields. The quantities of linear precursor and higher molecular weight condensation byproducts were low. The latter byproducts can be removed efficiently by classical fractionation using chloroform/heptane as solvent/nonsolvent pair. For the removal of linear precursor a process was developed which comprises the quantitative oxidation of alcoholic PEG chain ends to carboxyl groups and their subsequent removal with the help of a basic ion-exchange resin. The efficient cleaning processes allowed carrying out the ring closure reaction at relatively high concentrations and so increasing sample quantities. As a result, cyclic poly(ethylene glycol) was obtained in high purity up to a molecular weight of 20 000 g/mol in quantities of several grams. In order to monitor the oxidation reaction and to prove the absence of linear chains, a 1H NMR characterization technique was developed, which is extremely sensitive up to high molecular weights

Wood structure during pretreatment in ionic liquids

Cellulose makes up for most of the material in the lignocellulosic’s cell wall, and it could provide an abundant source for fuels, materials and chemicals. Mild and selective conversion processes would be desirable for decentralized value-generation from the synthesis power of nature. However, the utilization is still difficult due to the composition and the structure of the biomass’ cell wall. Cellulose shows a dense, crystalline structure and the access to these macromolecules is further restricted by lignin and hemicellulose. An efficient conversion hence requires the application of a pretreatment to gain access to cellulosic macromolecules for subsequent conversion processes.Mechanistic understanding of the pretreatment can likely be gained at the molecular level. However, the cellulose in the cell wall exists in fibrils made of several cellulose chains, which are hold together via intermolecular hydrogen bonds. This regular arrangement forms crystalline structures that are a major obstacle in enzymatic hydrolysis [1]. Hence, molecular analysis needs to be extended by structural analysis to monitor the mechanistic steps of pretreatment.Ionic liquids proved to be good solvents for the cellulose and the hydrophobic lignin [2], and the high concentrations of acetate at elevated temperatures around 100°C give rise to chemical reactions that constitute the desired pretreatment and improve the enzymatic hydrolysis [3]. Due to the abundance of water in such processes, we systematically studied the effect of water on this pretreatment. Using small angle neutron scattering (SANS), the tissue after the pretreatment was compared to the native wood and a first time-resolved setup was established for this pretreatment.The crystallinity of the cellulose has decayed at low water concentrations, and the cell structure of the wood is rather destroyed. At higher water contents, the crystallinity is enhanced, and the cell structure is rather preserved but cellulose fibrils show coalescence. Apart from that, various methods have been applied to support the results and will be presented selectively. Latest kinetic SANS measurements reveal the pretreatment process in more detail. [1] S.P. Chundawat, G.T. Beckham, M.E. Himmel, B.E. Dale, Annual Review of Chemical and Biomolecular Engineering, 2, 121–145 (2011).[2] J. Viell, W. Marquardt, Holzforschung, 65(4), 519 (2011).[3] J. Viell, H. Wulfhorst, T. Schmidt, U. Commandeur, R. Fischer, A. Spiess, W. Marquardt, Bioresource Technology 146, 144–151 (2013)

Structure of wood during pretreatment in ionic liquid/water mixtures

Cellulose makes up for most of the material in the lignocellulosic’s cell wall, and it could provide an abundant source for fuels, materials and chemicals. Mild and selective conversion processes would be desirable for decentralized value-generation from the synthesis power of nature. However, the utilization is still difficult due to the composition and the structure of the biomass’ cell wall. Cellulose shows a dense, crystalline structure and the access to these macromolecules is further restricted by lignin and hemicellulose. An efficient conversion hence requires the application of a pretreatment to gain access to cellulosic macromolecules for subsequent conversion processes.Mechanistic understanding of the pretreatment can likely be gained at the molecular level. However, the cellulose in the cell wall exists in fibrils made of several cellulose chains, which are hold together via intermolecular hydrogen bonds. This regular arrangement forms crystalline structures that are a major obstacle in enzymatic hydrolysis [1]. Hence, molecular analysis needs to be extended by structural analysis to monitor the mechanistic steps of pretreatment.Ionic liquids proved to be good solvents for the cellulose and the hydrophobic lignin [2], and the high concentrations of acetate at elevated temperatures around 100°C give rise to chemical reactions that constitute the desired pretreatment and improve the enzymatic hydrolysis [3]. Due to the abundance of water in such processes, we systematically studied the effect of water on this pretreatment. Using small angle neutron scattering (SANS), the tissue after the pretreatment was compared to the native wood and a first time-resolved setup was established for this pretreatment.The crystallinity of the cellulose has decayed at low water concentrations, and the cell structure of the wood is rather destroyed [4]. At higher water contents, the crystallinity is enhanced, and the cell structure is rather preserved but cellulose fibrils show coalescence. Apart from that, various methods have been applied to support the results and will be presented selectively. A latest kinetic SANS study completes the whole picture drawn here.[1] S.P. Chundawat et al., Annual Review of Chemical and Biomolecular Engineering, 2, 121–145 (2011).[2] J. Viell, W. Marquardt, Holzforschung, 65(4), 519 (2011).[3] J. Viell, H. Wulfhorst, T. Schmidt et al., Bioresource Technology 146, 144–151 (2013).[4] J. Viell, H. Inouye, N.K. Szekely, Henrich Frielinghaus et al., Biotechnol Biofuels 9:7 (2016