78239-14-2Relevant articles and documents
A Sustainable Heterogeneous Iron Catalyst Fe/SBA-15 towards Direct Arylation of Unactivated C(sp3)?H and C(sp2)?H Bonds with Arenes
Rajendran,Satishkumar
, p. 1284 - 1291 (2017/04/14)
Iron grafted over mesoporous silica (8 wt %Fe/SBA-15) is a sustainable, efficient heterogeneous iron catalyst for direct arylation of biphenyl methane C(sp3)?H and benzene C(sp2)?H bonds. The selective extraction deposition (SED) technique was adopted to graft iron easily over the mesoporous support SBA-15 by using LaFeO3 as an iron precursor. The synthesized catalyst has been characterized by EPR spectroscopy, diffuse reflectance UV/Vis spectroscopy, and temperature programmed reduction (TPR) analysis to understand the coordination environment and state of oxidic iron species grafted over the mesoporous SBA-15. TPR results confirm the presence of isolated, clustered, oligomeric oxidic iron species in the catalyst. The adopted SED technique is highly successful for grafting 8 wt % iron into the mesopores of SBA-15 without forming iron oxide particles. Unlike homogeneous iron, the 8 wt %Fe/SBA-15 catalyst does not need support from an electron-withdrawing group and additives to carry out arylation of benzene and could be successfully recycled five times.
Anomalous Acetoxylation of Aromatic Nuclei: Some Structural Requirements in the Substrate
Bandaranayake, Wickramasinghe M.,Riggs, Noel V.
, p. 115 - 129 (2007/10/02)
For certain aromatic nuclei, bromination in acetic acid in the presence of pyridine is accompanied by nuclear acetoxylation.As first observed with galbulin, when two alkoxyl groups, one meta and one para to a benzylic centre of the substrate are present, acetoxylation occurs at the intervening ortho position.Under the given conditions, acetoxylation occurs at position 8 of 6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydronaphthalene, and at position 2 of 3,4-dimethoxy diphenyl and triphenyl-methanes.Acetoxylation does not occur in the absence of either of the alkoxy groups or in the absence of pyridine, not does it occur in the pendant ring of 1-(3',4'-dimethoxyphenyl)-1,2,3,4-tetrahydronaphthalene.These results are consistent with the earlier suggestion that the reaction occurs by way of initial oxidative formation of a doubly benzylic cation
