Structural Aspects of Native and Acid or Enzyme Degraded Amylopectins - a 13C NMR Study

¹³C NMR signal assignments were achieved for amylopectin (from waxy maize starch) dissolved in dimethylsulfoxide mainly by comparison with the corresponding amylose spectrum and chemical shift arguments. From these data a branching degree of amylose and amylopectin of 1.4±0.5% and 6.0±0.7% could be estimated. Investigation of acid and enzyme degraded amylopectins by means of this method revealed that cleavage by these methods proceeded in an analogous manner. Thus, viewed from the standpoint of structural aspects they yielded virtually identical products.     

Fragranced consumer products: Formulation practices,related models,and recommendations to enable wider hydrophilic–lipophilic difference (HLD) application

Fragrances in consumer products are essential for appeal and market success. However, creating optimal stable formulas are especially challenging due to the polar nature of many fragrance ingredients. This perspective discusses how fragrances are currently dealt with within the industry, current surfactant and solvent models, and the barriers that today's industrial practice that prevent advancement to modeling and simulation. Recommendations for chemical suppliers, fragrance houses, and formulators are made regarding the implementation of the Hydrophilic-Lipophilic Difference with Net Average Curvature (HLD-NAC) model, which is the most comprehensive model for fragranced aqueous consumer products.     

Aryl-(4-arylimino-4H-pyrido[1,2-a]pyrazin-3-yl)amine–Synthese,Komplexbildung mit Molybdän(0) und Oxigenierung

Aryl-(4-arylimino-4H-pyrido[1,2-a]pyrazine-3-yl)amines-Synthesis, Complex Formation with Molybdenum(0) and Oxygenation The synthesis of p-tolyl(4-p-tolylimino-4H-pyrido [1,2-a]pyrazine-3-yl)amine 8 (TTPPA) is achieved by the reaction of 2-pyridylmethylamine with oxalic acid bis(p-tolylimidoyl)chloride. The ion-pair [Na(THF)₃][(TTPPAH)Mo(CO)₄] 4 is obtained by the reaction of the NH-acidic compound 8 with sodium bis(trimethylsilyl)amide and (nor)Mo(CO)₄ (nor = norbornadiene) dissolved in THF. The bidentate ligand anion TTPPA-H is related to the 1,4-diazadienes, but its n-donor effect is dominating. Its trans-influence results in different Mo-CO-bond lengths of 4 : 1.901 and 1.951 Å (trans-positions); 2.003 and 2.031 Å (cis-positions). In the cationic part of 4 the sodium is five-coordinate (distorted tetragonal pyramidal structure). Donor atoms are the three THF, N3 of TTPPA-H, and the oxygen atom of one CO of the moiety Mo(CO)₄. 8 is oxygenated by hydrogen peroxide or by dioxygen on heating. In the course of a ring transformation of the 6-membered pyrazine to the 5-membered imidazole cycle 3-p-tolyl-5-p-tolylimino-2-pyridine-2-yl-2,3-dihydro-imidazol-4-one 9 is formed. In THF two isomers 9 and 9a are observed in a molar ratio of about 1:1. 4 and 9 have been characterized by single crystal x-ray diffraction.     

Untersuchungen zur Vergleichbarkeit der statischen und dynamischen Überdruckprüfung von druckfesten Kapselungen

Forschung im Ingenieurwesen - Der Einsatz von elektrischen Geräten in explosionsgefährdeten Bereichen erfordert besondere Schutzmaßnahmen, um eine Zündung der...