Effect of residual contaminants and of different types of extrusion processes on the rheological properties of the post-consumer polypropylene

Rheological measurements were conducted to verify the influence of different mechanical recycling processes and the presence of contaminants on the degradation of post-consumer polypropylene. Firstly, polypropylene (PP) was contaminated to simulate a post-consumer material, following the protocol recommended by the FDA. PP was subsequently recovered (washed and dried) and the samples were submitted to different extrusion processes. The rheological data demonstrated that the different types of processing applied and the presence of contaminants altered the molecular structure of the samples. The contaminants acted as agents that accelerated the polymer degradation. The contaminated samples submitted to higher shear rates exhibited greater decrease in their molar mass and a slight narrowing in the molar mass distribution. Also, it was observed that the most degraded samples showed decrease in their molar mass, in the viscosity and in the level of their molecular entanglements. These samples also exhibited a more Newtonian behavior and their molar mass distribution showed a slight narrowing. By calculating the ratio of the molar mass it was possible to quantify the degree of degradation of PP samples, confirming the results obtained.     

Design and synthesis of novel 1,4-benzodiazepine surrogates as potential CCKA and CCKB antagonists via palladium-catalyzed three-component cascade reactions

Structurally diverse novel 1,4-benzodiazepine analogues related to selective CCKA antagonist MK-329, and CCKB antagonists L-365,260 and YM022 are prepared via palladium-catalyzed three component domino reactions involving allenylation-carbonylation-anion capture in one-pot cascade protocol in good to excellent yields.     

The Fluorenyl Cation

The fluorenyl cation is a textbook example for a 4π antiaromatic cation. However, contrasting results have been published on how the annelated benzene rings compensate the destabilizing effect of the 4π antiaromatic five‐membered ring in its core. Whereas previous attempts to synthesize this cation in superacidic media resulted in undefined polymeric material only, we herein report that it can be generated and isolated in amorphous water ice at temperatures below 30 K by photolysis of diazofluorene. Under these conditions, the fluorenylidene is protonated by water to give the fluorenyl cation, which could be characterized spectroscopically. Its absorption in the visible‐light range matches that previously obtained by ultrafast absorption spectroscopy, and furthermore, its IR spectrum could be recorded. The IR bands in amorphous ice very nicely match predictions from DFT and DFT/MM calculations, suggesting the absence of strong interactions between the cation and surrounding water molecules.     

Comment on “Diferential transform method for the solutions to some initial value problems in chemistry”

Journal of Mathematical Chemistry - We argue that the differential transform method is merely the well known Taylor series approach in disguise. We show that the examples chosen by Qin and Lou have...