MAu₂GeS₄-Chalcogel (M = Co, Ni): Heterogeneous Intra- and Intermolecular Hydroamination Catalysts

Abstract

High surface area macroporous chalcogenide aerogels (chalcogels) MAuGeS (M = Co, Ni) were prepared from KAuGeS precursor and Co(OAc) or NiCl by one-pot sol-gel metathesis reactions in aqueous media. The MAuGeS-chalcogels were screened for catalytic intramolecular hydroamination of 4-pentyn-1-amine substrate at different temperatures. 87% and 58% conversion was achieved at 100 °C, using CoAuGeS- and NiAuGeS-chalcogels respectively, and the reaction kinetics follows the first order. It was established that the catalytic performance of the aerogels is associated with the M centers present in the structure. Intermolecular hydroamination of aniline with 1-R-4-ethynylbenzene (R = -H, -OCH, -Br, -F) was carried out at 100 °C using CoAuGeS-chalcogel catalyst, due to its promising catalytic performance. The CoAuGeS-chalcogel regioselectively converted the pair of substrates to respective Markovnikov products, (E)-1-(4-R-phenyl)-N-phenylethan-1-imine, with 38% to 60% conversion.

Fluxomics - New Metabolomics Approaches to Monitor Metabolic Pathways

“…NMR is a non-destructive, non-selective and fast method that has been widely used for molecular identification and structural elucidation used with minimal sample preparation requirements ( Atiqullah et al, 2015 ; Alahmari et al, 2019 ; Dhahri et al, 2020 ). While the sample is placed in a static magnetic field, it can be recovered for future analysis using other techniques and it is possible to obtain spectral results regarding how molecules move, flex, react, appear/disappear, or bind with other molecules over several time scales, providing an optimum approach for fluxomics ( Blindauer et al, 1997 ; Wolak et al, 2012 ; Nargund et al, 2013 ; Davaasuren et al, 2017 ).…”

NMR as a “Gold Standard” Method in Drug Design and Discovery

“…As we have attempted to emphasize and demonstrate, NMR has a powerful and unique role in drug design. NMR provides detailed structural information about a molecule along with kinetic information over extended time periods, i.e., not just a snapshot [ 24 , 25 ]. Moreover, NMR is quantitative and highly reproducible, allowing applications in diverse fields such as relaxometry, combinatorial chemistry, fluxomics, and targeted analysis [ 91 ].…”

“…In contrast to mass spectrometry, NMR is non-destructive, non-invasive, has extremely high reproducibility permitting researchers to acquire measurements under different experimental conditions (e.g., temperature, time points, and concentrations) often while the same sample is inside the magnet [ 19 , 20 , 21 , 22 , 23 ]. NMR can be used in reaction kinetic studies while several consecutive measurements are taken, and while spectral changes (function of the reaction time) are analyzed [ 24 , 25 , 26 , 27 , 28 ]. Moreover, molecules are studied at the atomic level [ 29 , 30 , 31 ].…”

Heterogeneously Catalysed Hydroamination

“…Chalcogenide based aerogels or chalcogels have appeared as an interesting class of compounds to generate industrially important heterocyclic amines via hydroamination. High surface area Co and Ni based chalcogels (MAu 2 GeS 4 ) have been testified and found catalytically active towards both intramolecular and intermolecular hydroamination [33] . Kinetic study reveals Co and Ni based chalcogels promoted catalytic amination follows first order kinetics and rate determining step as the step of binding of the substrate to the catalytically active Lewis acidic sites of the chalcogels.…”