High iso Aldehyde Selectivity in the Hydroformylation of Short‐Chain Alkenes

The hydroformylation of propene to give predominantly iso‐butanal has been achieved; class‐leading selectivity is possible even at higher temperatures that deliver fast conversion. Racemic rhodium complexes of bidentate phospholane phosphites derived from tropos‐biphenols and unusual solvent systems are the key to the selectivity observed.     

Top‐Down Fabrication of Stable Methylammonium Lead Halide Perovskite Nanocrystals by Employing a Mixture of Ligands as Coordinating Solvents

A top‐down method is demonstrated for the fabrication of CH₃NH₃PbBr₃ and CH₃NH₃PbI₃ perovskite nanocrystals, employing a mixture of ligands oleic acid and oleylamine as coordinating solvents. This approach avoids the use of any polar solvents, skips multiple reaction steps by employing a simple ultrasonic treatment of the perovskite precursors, and yields rather monodisperse blue‐, green‐, and red‐emitting methylammonium lead halide nanocrystals with a high photoluminescence quantum yield (up to 72 % for the green‐emitting nanocrystals) and remarkably improved stability. After discussing all relevant reaction parameters, the green‐emitting CH₃NH₃PbBr₃ nanocrystals are employed as a component of down‐conversion white‐light‐emitting devices_.     

Fast and Minimal‐Solvent Production of Superinsulating Silica Aerogel Granulate

With their low thermal conductivity (λ ), silica aerogels can reduce carbon emissions from heating and cooling demands, but their widespread adoption is limited by the high production cost. A one‐pot synthesis for silica aerogel granulate is presented that drastically reduces solvent use, production time, and global warming potential. The inclusion of the hydrophobization agent prior to gelation with a post‐gelation activation step, enables a complete production cycle of less than four hours at the lab scale for a solvent use close to the theoretical minimum, and limits the global warming potential. Importantly, the one‐pot aerogel granulate retains the exceptional properties associated with silica aerogel, mostly λ =14.4±1.0 mW m⁻¹⋅K⁻¹ for the pilot scale materials, about half that of standing air (26 mW m⁻¹⋅K⁻¹). The resource‐, time‐, and cost‐effective production will allow silica aerogels to break out of its niche into the mainstream building and industrial insulation markets.