17881-67-3Relevant articles and documents
Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
, p. 3260 - 3269 (2019/03/11)
The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
The site-selective functionalization of halogen-bearing phenols: An exercise in diversity-oriented organometallic synthesis
Marzi, Elena,Schlosser, Manfred
, p. 3393 - 3401 (2007/10/03)
The organometallic approach to diversity-oriented organic synthesis was subjected to a further test, this time in the phenol series. The model compounds selected were 2,3,6-trifluorophenol, the three isomers of (trifluoromethoxy) phenol and the three isomers of chlorophenol. A combination of optionally site selective metalations and protective group-controlled metalations enabled the selective generation of several isomeric intermediates in each case and their subsequent conversion into functionalized derivatives, in particular hydroxybenzoic acids.
Gas-phase thermolysis of tert-butyl hydroperoxide with benzene and chlorobenzene in the temperature range 200-300 deg C
Mulder, Peter,Louw, Robert
, p. 282 - 287 (2007/10/02)
Thermolysis of tert-butyl hydroperoxide (1) in nitrogen with an excess of benzene in the temperature range 200-300 deg C, leads to biphenyl (2) as the only observable benzene-derived product.With chlorobenzene, dichlorobiphenyls (4) are formed, together with chlorobiphenyl (5), ca. 12percent on 4, and phenol (20-25percent on 4); chlorophenols are not produced.The use of ca. equimolar quantities of iodine based on 1 results in formation of iodobenzene (3) and chloroiodobenzenes (7), respectively, at the expense of biaryl.In air, chlorobenzene and 1 produce chlorophenols (8), biaryl then being a minor product.Hydroxyl radicals produced from 1 abstract hydrogen from benzene to give phenyl radicals (Ph.) which, in notrogen, arylate benzene.From isomer distributions of 7 and of 4 it is inferred that hydrogen abstraction from chlorobenzene leads to chlorophenyl radicals, with a ratio o/m/p ca. 24/52/24.With chlorobenzene, ipso substitution, PhCl + .OH -> PhOH, also takes place.In the presence of oxygen or iodine, formation of biaryls involves irreversible addition of (chloro)phenyl radical, the intermediate adduct radicals reacting with oxygen or iodine.In nitrogen, however, the first step in arylation is reversible.Apart from undergoing O-O bond homolysis, 1 is attacked by .Me (formed from Me3CO.) and, to some extent, by aryl radicals.A large arene/1 intake ratio (>100), or the addition of either iodine or air suppresses - or even prevents - free-radical-induced decomposition of 1.
