917-71-5Relevant articles and documents
Catalytic Oxidative Cracking of Benzene Rings in Water
Shimoyama, Yoshihiro,Ishizuka, Tomoya,Kotani, Hiroaki,Kojima, Takahiko
, p. 671 - 678 (2019/01/08)
Efficient degradation of harmful benzene rings in water is indispensable for achieving a clean water environment. We report herein unprecedented catalytic oxidative benzene cracking (OBC) in water using a ruthenium(II)-aqua complex having an N-heterocyclic carbene ligand as a catalyst and a cerium(IV) salt as a sacrificial oxidant under mild conditions. The OBC reactions produced carboxylic acids such as formic acid, which can be converted to dihydrogen directly from the OBC solution using a rhodium(III) catalyst with adjustment of the solution pH to 3.3. The OBC reactions can be applied to monosubstituted benzene derivatives such as ethylbenzene, chlorobenzene, and benzoic acid. Initial rates of the OBC reactions showed a linear relationship in the Hammett plot with a negative slope, indicating the electrophilicity of a Ru(III)-oxyl complex as the reactive species in the catalytic OBC reaction. Also, we discuss a plausible mechanism of the catalytic OBC reactions based on the kinetic analysis and the product stoichiometry for the OBC reaction of nonvolatile sodium m-xylene sulfonate. The addition of an electrophilic radical to the aromatic ring to form arene oxide/oxepin is proposed as the initial step of the OBC reaction.
SELECTIVE CARBON-CARBON BOND CLEAVAGE BY EARTH ABUNDANT VANADIUM COMPOUNDS UNDER VISIBLE LIGHT PHOTOCATALYSIS
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Page/Page column 48, (2016/09/22)
Provided herein a vanadium(V) complex of formula I, where R1 to R8 are as defined herein. Also provided herein are reactions making use of the vanadium(V) complex of formula I, such as selective sp3-sp3 carbon-carbon bond cleavage under visible light photocatalysis and photodegradation of lignin.
Selective photocatalytic C-C bond cleavage under ambient conditions with earth abundant vanadium complexes
Gazi, Sarifuddin,Hung Ng, Wilson Kwok,Ganguly, Rakesh,Putra Moeljadi, Adhitya Mangala,Hirao, Hajime,Soo, Han Sen
, p. 7130 - 7142 (2015/11/24)
Selective C-C bond cleavage under ambient conditions is a challenging chemical transformation that can be a valuable tool for organic syntheses and macromolecular disassembly. Herein, we show that base metal vanadium photocatalysts can harvest visible light to effect the chemoselective C-C bond cleavage of lignin model compounds under ambient conditions. Lignin, a major aromatic constituent of non-food biomass, is an inexpensive, accessible source of fine chemical feedstocks such as phenols and aryl ethers. However, existing lignin degradation technologies are harsh and indiscriminately degrade valuable functional groups to produce intractable mixtures. The selective, photocatalytic depolymerization of lignin remains underexplored. In the course of our studies on lignin model compounds, we have uncovered a new C-C activation reaction that takes place under exceptionally mild conditions with high conversions. We present our fundamental studies on representative lignin model compounds, with the aim of expanding and generalizing the substrate scope in the future. Visible light is employed in the presence of earth-abundant vanadium oxo catalysts under ambient conditions. Selective C-C bond cleavage leads to valuable and functionally rich fine chemicals such as substituted aryl aldehydes and formates. Isotope labeling experiments, product analyses, and intermediate radical trapping, together with density functional theory studies, suggest a unique pathway that involves a photogenerated T1 state during the C-C bond cleavage reactions. Our study demonstrates a sustainable approach to harvest sunlight for an unusual, selective bond activation, which can potentially be applied in organic transformations and biomass valorization.
