Über Derivate des Isatins und des Dioxindols

Ohne Zusammenfassung     

Über Herstellung und Eigenschaften kolloidzerteilter Gase sowie ihre Bedeutung in Natur und Technik

Ohne Zusammenfassung Aus dem Inhalt eines Gastvortrages von A. Krause in Greifswald am 1. II. 1936. Vgl. K. Kapitańczyk, Diss. (Posen 1935). Preisgekr?nt im „Radocha-A. G. “-Preisausschreiben 1937, Warschau, Techn. Hochsch., Chem. Fakult?t.     

Über den Einfluß der Acetylierung der Phenolgruppe auf die Nitrierungsgeschwindigkeit und Messung derselben bei Phenolen in Äther

Ohne Zusammenfassung     

On effects of thickness on ductile crack growth in mild steel

Critical crack opening displacement (COD) values have been examined for a range of specimen thicknesses. The COD at the initiation of fracture δ₁ is found to be constant, given a plane-strain crack-tip stress-state, whereas the COD at maximum load δ_max decreases with increasing thickness. The loads required to produce instability are found to vary with thickness, in a way analogous to behaviour observed under linear elastic conditions. Crack growth under constant load for a range of specimen thicknesses has been examined, and failure has been found to occur at loads below that associated with Δ_max,; the minimum load per unit thickness required to cause failure decreasing with specimen thickness.     

Exploring catalytic solid/liquid interfaces by in situ attenuated total reflection infrared spectroscopy

In situ attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy has gained considerable attention as a powerful tool for exploring processes occurring at solid/liquid and solid/liquid/gas interfaces as encountered in heterogeneous catalysis and electrochemistry. Understanding of the molecular interactions occurring at the surface of a catalyst is not only of fundamental interest but constitutes the basis for a rational design of heterogeneous catalytic systems. Infrared spectroscopy has the exceptional advantage to provide information about structure and environment of molecules. In the last decade, in situ ATR-FT-IR has been developed rapidly and successfully applied for unraveling processes occurring at solid/liquid interfaces. Additionally, the kinetics of complex reactions can be followed by quantifying the concentration of products and reactants simultaneously in a non-destructive way. In this tutorial review we discuss some key aspects which have to be taken into account for successful application of in situ ATR-FT-IR to examine solid/liquid catalytic interfaces, including different experimental aspects concerned with the internal reflection element, catalyst deposition, cell design, and advanced experimental methods and spectrum analysis. Some of these aspects are illustrated using recent examples from our research. Finally, the potential and some limitations of ATR will be elucidated.     

Tuning the mechanical properties of silica microcapsules

Heat treatment is a standard method to increase the hardness of silica in various applications. Here, we tested the effect of high temperature annealing on the mechanical properties of silica microcapsules by force spectroscopy under point loads applied to the particle shell. The Young's modulus of the shells moderately increases after annealing at temperatures above 500 °C. Temperatures over 850 °C result in a much stronger increase and the Young's modulus is close to that of fused silica after annealing at 1100 °C. NMR analysis revealed that in untreated microcapsules synthesized by seeded growth using the St?ber method only 55% of the silicon atoms form siloxane bonds with four neighbors, whereas the remaining ones only form three or less siloxane bonds each and, thus, a large number of ethoxy and silanol groups still exist. During annealing at 500 °C, these are successively transformed into siloxane bonds through condensation reactions. This process correlates with only a moderate increase in Young's modulus. The strong increase at temperatures above 850 °C was associated with a densification which was associated by a decrease in capsule size and shell thickness while the shells remained homogenous and of spherical shape. The main strengthening of the shells is thus mainly due to compaction by sintering at length scales significantly larger than that of local siloxane bonds.     

Structural effects in the Pd-induced enantioselective deprotection–decarboxylation of β-ketoesters

Structural effects in the chiral base and the influence of some key reaction parameters (catalyst type and solvent) in the Pd-induced enantioselective decarboxylation (cascade reaction) of three different ,-disubstituted benzyl β-ketoesters were explored. The reaction intermediate after debenzylation (β-keto-carboxylic acid) was synthesized and its decarboxylation studied independently. The highest ee (up to 60%) in the cascade reaction was achieved with those substrates that contained an aromatic ring system and with chiral amino alcohols that possessed an extended aromatic ring (quinine and quinidine). Polar solvents with weak H-bond donor and acceptor properties favor enantioselection.     

Über Abkömmlinge der Nitrohemipinsäure

Ohne Zusammenfassung     

Selective reagent ionisation‐time of flight‐mass spectrometry: a rapid technology for the novel analysis of blends of new psychoactive substances

In this study we demonstrate the potential of selective reagent ionisation‐time of flight‐mass spectrometry for the rapid and selective identification of a popular new psychoactive substance blend called ‘synthacaine’, a mixture that is supposed to imitate the sensory and intoxicating effects of cocaine. Reactions with H₃O⁺ result in protonated parent molecules which can be tentatively assigned to benzocaine and methiopropamine. However, by comparing the product ion branching ratios obtained at two reduced electric field values (90 and 170 Td) for two reagent ions (H₃O⁺ and NO⁺) to those of the pure chemicals, we show that identification is possible with a much higher level of confidence then when relying solely on the m/z of protonated parent molecules. A rapid and highly selective analytical identification of the constituents of a recreational drug is particularly crucial to medical personnel for the prompt medical treatment of overdoses, toxic effects or allergic reactions. Copyright © 2015 John Wiley & Sons, Ltd.