10.1021/ja4060178
The research investigates the room temperature dehydrogenation of ethane, propane, linear alkanes C4?C8, and some cyclic alkanes by a transient titanium neopentylidyne complex, [(PNP)Ti?CtBu] (A). The purpose is to explore an efficient and mild method for converting natural gas components into more useful commodity reagents, addressing the global energy crisis and the need for sustainable chemical transformations. The study demonstrates that complex A can dehydrogenate these alkanes to form olefin complexes, such as [(PNP)Ti(η2-H2C-CHR)(CH2 tBu)] (R = H, CH3, CH2CH3, nPr, nBu), through a mechanism involving sequential 1,2-CH bond addition and β-hydrogen abstraction. Computational studies reveal that the formation of terminal olefins is both kinetically and thermodynamically favorable. The olefin complexes can be liberated using oxidants like N2O and organic azides. The research concludes that this titanium-based system offers a promising pathway for alkane dehydrogenation under mild conditions, potentially leading to more sustainable and energy-efficient processes for converting natural gas into valuable chemicals.
10.1021/ma011959p
The research focuses on the synthesis and gas transport properties of new high glass transition temperature ring-opened polynorbornenes, specifically the polymers and copolymers derived from N-(1-adamantyl)-exo-norbornene-5,6-dicarboximide (AdNDI), N-cyclohexyl-exo-norbornene-5,6-dicarboximide (ChNDI), and N-phenyl-exonorbornene-5,6-dicarboximide (PhNDI). The experiments involved the preparation of membranes from these homopolymers and copolymers, and the subsequent measurement of the transport of various gases (hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide, methane, ethylene, and ethane) across these membranes at 30°C using permeation techniques. The study aimed to determine the diffusion coefficients and permselectivity coefficients for different gases, which were influenced by the chemical structure of the membranes. The analyses included 1H and 13C NMR spectroscopy, FTIR spectroscopy, glass transition temperature measurements, and molecular weight determinations via GPC. The results indicated that diffusion coefficients correlated with the diameter of diffusant molecules, and the permselectivity coefficients varied depending on the type of membrane, with some membranes showing high permselectivity for certain gas pairs, such as oxygen with respect to nitrogen, and ethylene with respect to ethane.
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