Chemisches Kolloquium der T. H. Braunschweig

Matter‐Wave Metrology as a Complementary Tool for Mass Spectrometry

“…343343-17-9, purity 90 %), shown in Figure 2, which has been developed as a palladium catalyst for cross-coupling reactions in fluorinated media. [10,11] The intact molecule has a mass of 3378.5 amu, but quadrupole mass spectroscopy reveals predominantly a compound with a mass of 1601 amu, which corresponds to the mass of the triphenylphosphine ligand 2 (C 48 H 24 F 51 P).…”

“…Pronounced differences were observed in the 31 P NMR spectra of both samples. Whereas 1 has a 31 P NMR signal at d = 20.9 ppm, [10] the sample collected from the copper plate has a peak at d = 10.8 ppm. Thus, the sublimed species creating the molecular wave is not the entire palladium complex 1, but rather a fragment.…”

Dimension Changes in a Chemomechanical Polymer Containing Ethylenediamine and Alkyl Functions as Selective Recognition Units

“…In the presence of salts or buffers such as 0.02 m to 0.05 m Na 2 HPO 4 /NaH 2 PO 4 , organic substrates such as AMP, [20] in contrast with most metal ions, often showed a regular increase with effector concentration, while the magnitude of the increase depended on the film particle size and also on the presence of a buffer (see cooperativity effects) (Figure 8, Figure S9). With no buffer or lower concentrations of buffer (Figure 9), one again often obtained a maximum around the same effector concentrations as with most metal ions (e.g., with benzoic acid).…”

“…The major difference of our approach to the polymer-based techniques described above lies in the implementation of supramolecular binding sites in polymeric networks in such a way that interaction with substrates induces selective macroscopic size changes (often, but not necessarily, expansion), not necessarily by phase changes of the gels. [20,21] Host units developed in traditional solution supramolecular chemistry are immobilized in polymer networks that possess sufficient flexibility, absorbance capacity, and uptake or release velocity for selected substrates to ensure a large mechanical response within reasonable time. Furthermore, it has previously been shown that introduction even of simple recognition elements into such networks can result in cooperative effects including macroscopic logical gate functions, [22] which are actually more difficult to produce with supramolecular systems in solution.…”

Synthesis of Enantiomerically Pure Pheromones of South‐Pacific Brown Algae: Hormosirene and Dictyopterene A

“…As the starting material in most cases served ethyl trans-vinylcyclopropanecarboxylate (rac -3; trans) which is readily accessible in large quantities from butadiene and ethyl diazoacetate [7]. Our strategy also starts with a 1 : 1 mixture of ethyl cis-and truns-vinylcyclopropanecarboxylate, but utilizes the diastereoselective saponification of the isomers with pig-liver esterase [8]. The trans-ester is preferentially hydrolyzed, and the acid rac-4 is obtained in 87% yield and an isomeric purity of > 98.5 YO.…”