56892-31-0Relevant academic research and scientific papers
Regiospecific oxidation of polycyclic aromatic phenols to quinones by hypervalent iodine reagents
Wu, Anhui,Duan, Yazhen,Xu, Daiwang,Penning, Trevor M.,Harvey, Ronald G.
experimental part, p. 2111 - 2118 (2010/04/26)
The hypervalent iodine reagents o-iodoxybenzoic acid (IBX) and bis(trifluoro-acetoxy)iodobenzene (BTI) are shown to be general reagents for regio-controlled oxidation of polycyclic aromatic phenols (PAPs) to specific isomers (ortho, para, or remote) of polycyclic aromatic quinones (PAQs). The oxidations of a series of PAPs with IBX take place under mild conditions to furnish the corresponding ortho-PAQs. In contrast, oxidations of the same series of PAPs with BTI exhibit variable regiospecificity, affording para-PAQs where structurally feasible and ortho-PAQs or remote PAQ isomers in other cases. The structures of the specific PAQ isomers formed are predictable on the basis of the inherent regioselectivities of the hypervalent iodine reagents in combination with the structural requirements of the phenol precursors. IBX and BTI are recommended as the preferred reagents for regio-controlled oxidation of PAPs to PAQs.
Tetrabutylammonium Hydroxide: A Reagent for the Base-Catalyzed Dehydration of Vicinal Dihydro Diols of Aromatic Hydrocarbons. Implications to Ion-Pair Chromatography
McCourt, David W.,Roller, Peter P.,Gelboin Harry V.
, p. 4157 - 4161 (2007/10/02)
Vicinal dihydro diols of benzopyrene and benzanthracene are dehydrated to their phenolic derivatives by the methanol eluate of reverse-phase (octadecylsilane) columns previously treated with tetrabutylammonium phosphate.Phenols are also produced by treating the dihydro diols with methanolic tetrabutylammonium hydroxide on removal solvent.In most cases the regioselectivity is markedly different from the acid-catalyzed dehydration.The in situ generated tetrabutylammonium phenoxides are converted to the butyl ethers at high temperatures (150 deg C) but not under th e conditions of dehydration (60 deg C).Tetraethylammonium and tetramethylammonium hydroxides also dehydrate dihydro diols, whereas potassium and sodium hydroxides do not.Dehydration does occur by treatment of dihydro diols with potassium hydroxide in the presence of 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) and with sodium methoxide in the presence of tetrabutylammonium chloride.A mechanism is suggested.
