Collect. Czech. Chem. Commun. 1996, 61, 1729-1737

Photochemical Hydroxylation of Salicylic Acid with Hydrogen Peroxide; Mechanistic Study of Substrate Sensitized Reaction

Kamil Lang, Jiřina Brodilová and Stanislav Luňák

Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 160 00 Prague 6, Czech Republic


The photochemical hydroxylation of salicylic acid (SA) by hydrogen peroxide proceeds via the same intermediate independently of the excited reactant (i.e. SA or H2O2). This conclusion is supported by the similar effect of pH on the quantum yields and on the isomer ratio of formed products: 2,3-dihydroxybenzoic acid (2,3-DHB) and 2,5-dihydroxybenzoic acid (2,5-DHB). The product ratio ([2,3-DHB]/[2,5-DHB]) is not affected by H2O2 concentration.

Keywords: 2-Hydroxybenzoic acid; Hydrogen peroxide; Photochemical hydroxylation.