Oxidation of halobenzenes by OH radical produced radiolytically in aqueous solution

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2021-10, Vol.187, p.109525, Article 109525
• Main Authors: Guadalupe, Albarrán, Rosalba, Ramos-Morales, Edith, Mendoza
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Aromatic compounds; Charge distribution; Chlorobenzene; Density distribution; Dilution; Distribution of electronic density; Electron density; Halobenzenes; o-, m- and p-halophenols; Oxidation; Radiation chemical yields; Radiolysis; Radiolytic oxidation; Rate constants; Relative partial rate constants
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2021.109525

The radiolytic oxidation of aromatic compounds in dilute aqueous solution is due to the electrophilic strength of the •OH that results from the radiolysis of water. This radical is preferentially added to the electron-rich centers in aromatic rings. Therefore, studies of the charge distribution of the hydroxycyclohexadienyl radicals produced by the addition of the •OH to the aromatics can provide information about their charge distribution. In the present work, the radiolytic oxidation reaction of fluorobenzene, chlorobenzene, bromobenzene, and iodobenzene with the •OH in diluted aqueous solutions was studied. The identification and quantification of the radiolytic products thus formed were carried out utilizing HPLC. The yields found for fluorobenzene, chlorobenzene, bromobenzene, and iodobenzene were 0.609, 0.527, 0.508, and 0.501 μmol/J, respectively. The electron density distribution in fluorobenzene, chlorobenzene, and bromobenzene was in the following order: for para > ortho > meta » ipso; however, in iodobenzene, there is a higher electron density in the "ortho" position than in the "para" position. From the total reaction rates for the halobenzenes with the •OH, the partial rate constants were obtained for the reaction of the •OH with each of the positions in the halobenzenes. •Study of radiolytic oxidation of halobenzenes in aqueous solution.•Distribution of products from irradiated halobenzenes in aqueous solution.•Distribution of electronic density in the aromatic ring of halobenzenes.•Inductive and resonance effects in iodobenzene.•Relative partial rate constants of halobenzenes.