Neue Phellandren-Derivate aus dem Wurzelöl von Angelica archangelicaL

New Phellandrene Derivatives from the Root Oil of Angelica archangelica L . 2-Nitro-1,5-p-menthadiene ( 5 ), trans- and cis-6-nitro-1(7), 2-p-menthadiene ( 6 and 7 ), trans-1(7), 5-p-menthadien-2-yl acetate ( 9 ) and a formal phellandrene derivative, 7-isopropyl-5-methyl-5-bicyclo [2.2.2]octen-2-one ( 16 ), have been identified in the root oil of Angelica archangelica L . Starting from (?)-(R)-α-phellandrene ( 1 ) (R)- 5 , (4R, 6S)- 6 /(4R, 6R)- 7 , (2S, 4R)- 9 and (1R, 4R, 7R)- 16 as well as (2S, 4R)- 11 , (2R, 4R)- 12 and (2R, 4R)- 10 have been prepared.     

Melt drawing as a route to high performance polyethylene

Well established routes for obtaining stiff and strong polyethylene (PE) involve solid state drawing either of solution crystallized gel films or melt crystallized spherulitic PE. The aim of this work is to show the potential of melt deformation as an alternative route for obtaining highly oriented products. Our previous work on the melt deformation route showed that oriented PE fibers could be directly extruded under appropriately controlled conditions [8,9]. Here, we show that PE films (or filaments) can also be melt drawn in the temperature window 130–160 °C, thus yielding oriented products. The advantage of melt drawing over direct melt extrusion is that it allows a wider operational latitude and thus does not require such carefully controlled conditions.The morphology produced by melt deformation is different from solid state deformation and consists of extended chain fibrils with platelet overgrowths. The relative amount of fibrils and platelets depends on operating parameters. The temperature window of PE melt drawing is identified with the regime where some flow induced crystallization takes place. The conditions for melt drawability are of wider generality for crystallizable flexible chain polymers. They are: (i) adequate strain rate to overcome entropie resistance to chain extension, (ii) but not high enough to activate the elastic response of the transient networks in the entangled system, (iii) sufficient strain to fully extend the chain, (iv) appropriate temperature for flow-induced crystallization and strain hardening, and (v) cooling to freeze the oriented structure.Ultra high molecular weight PEs were not the most suitable for melt drawing due to their high recoverable elongation in the melt (melt elasticity) in addition to added limitations imposed by their nascent grain systeme. Our work suggests that an optimum molecular weight for melt drawing is¯M _w(400–900)×10³ with further possibilities for improvement through multimodal distributions.     

Über Münzmetall‐Quecksilber‐Chalkogenidhalogenide. IV1) Hydrothermalsynthese und Kristallstruktur von CuHgSI und CuHg2S2I

On Coinage Metal Mercury Chalcogenide Halides. IV Hydrothermal Synthesis and Crystal Structure of CuHgSI and CuHg₂S₂I The hydrothermal reaction of CuI with α‐HgS in diluted aqueous HI‐solution as solvent at 180 °C yields dark red crystals of CuHgSI. The compound crystallizes orthorhombic in the space group Pna2₁ with a = 718.3(1) pm, b = 834.3(2) pm and c = 698.9(1) pm and Z = 4. CuHg₂S₂I was obtained by the hydrothermal reaction of CuI with α‐HgS in diluted HI‐solution at 300 °C as black crystals. The compound crystallizes orthorhombic in the space group Cmc2₁ with a = 1261.8(3) pm, b = 722.4(1) pm and c = 693.7(1) pm and Z = 4. Both crystal structures could be explained as distorted version of the Wurtzite structure type in which two different types of anion‐lattices are built up.     

Dilute acid pretreatment of softwoods

Selective thinning of forests in the western United States will generate a large, sustainable quantity of softwood residues that can be an attractive feedstock for fuel ethanol production. The major species available from thinning of forests in northern California and the eastern Rocky Mountains include white fir (Abies concolor), Douglas fir (Pseudotsuga menziesii), and Ponderosa pine (Pinus ponderosa). Douglas fir chips were soaked in 0.4% sulfuric acid solution, then pretreated with steam at 200 – 230°C for 1 – 5 min. After pretreatment, 90 – 95% of the hemicellulose and as much as 20% of the cellulose was solubilized in water, and 90% of the remaining cellulose can be hydrolyzed to glucose by cellulase enzyme. The prehydrolysates, at as high as 10% total solid concentration, can be readily fermented by the unadapted yeastSaccharomyces cerevisiae D₅A.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Formation de l'instabilité hélicoidale d'un Screw-pinch mesurée au moyen de sondes magnétiques dipolaires

Sans résumé