19618-15-6Relevant articles and documents
A partially serendipitous discovery of thermo-switchable ruthenium olefin metathesis initiator that seem to be well suited for ROMP of monomers bearing vinyl pendant groups
Szwaczko, Katarzyna,Czelu?niak, Izabela,Grela, Karol
, p. 146 - 153 (2017)
A latent Ru olefin metathesis catalyst bearing a chelating ligand with an azoxybenzene fragment was obtained and characterized. The complex was inactive in the ring closing metathesis (RCM) reaction of a standard test diene: diethyl diallylmalonate at room temperature but can be subsequently activated by elevated temperature (up to 100 °C). The lack of activity of this azoxy catalyst in RCM of dienes containing terminal C-C double bonds at room temperature and high activity in ring opening metathesis polymerization (ROMP) of bicyclo [2.2.1]hept-2-ene (norbornene, NBE) permitted the ROMP of the challenging monomer: 5-vinyl-2-norbornene yielding soluble polymers with cyclopentenylenevinylene chains with vinyl pendant groups.
Continuous Flow Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzenes with Gel-Bound Catalysts
Schmiegel, Carsten J.,Berg, Patrik,Obst, Franziska,Schoch, Roland,Appelhans, Dietmar,Kuckling, Dirk
, p. 1628 - 1636 (2021/03/15)
In the search for a new synthetic pathway for azoxybenzenes with different substitution patterns, an approach using a microfluidic reactor with gel-bound proline organocatalysts under continuous flow is presented. Herein the formation of differently substituted azoxybezenes by reductive dimerization of nitrosobenzenes within minutes at mild conditions in good to almost quantitative yields is described. The conversion within the microfluidic reactor is analyzed and used for optimizing and validating different parameters. The effects of the different functionalities on conversion, yield, and reaction times are analyzed in detail by NMR. The applicability of this reductive dimerization is demonstrated for a wide range of differently substituted nitrosobenzenes. The effects of these different functionalities on the structure of the obtained azoxyarenes are analyzed in detail by NMR and single-crystal X-ray diffraction. Based on these results, the turnover number and the turnover frequency were determined.
Silica encapsulated magnetic nanoparticles-supported Zn(II) nanocatalyst: A versatile integration of excellent reactivity and selectivity for the synthesis of azoxyarenes, combined with facile catalyst recovery and recyclability
Sharma,Monga, Yukti
, p. 1 - 10 (2013/08/25)
A novel and highly efficient zinc based nanocatalyst has been synthesized by covalent grafting of 2-acetylpyridine on amine functionalized silica@magnetite nanoparticles, followed by metallation with zinc acetate. The resulting nano-composite was found to be highly efficient for oxidation of various aromatic amines to give azoxyarenes. The prepared nanocatalyst was characterized by Electron microscopy techniques (SEM and TEM with EDS), X-ray diffraction (XRD), vibrational sampling magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR) and atomic absorption spectroscopy (AAS) techniques. High turnover number (TON), mild reaction conditions and high selectivity for azoxyarenes with sustained catalytic activity makes present protocol worthy and highly compliant as compared to the other non-magnetic heterogeneous catalytic system. The acquisition of this nanocatalyst is also exemplified by employing the catalyst in leaching and reusability test and the results from the tests showing negligible zinc leaching and recycling was achieved multiple times just by sequestering using an external magnet.
