Laser-induced photochemical reaction of aqueous maleic acid solutions containing H2O2

Hydroxy acid such as glycolic, tartaric and malic acids was directly produced by XeF-laser irradiation of the N2-saturated maleic acid aqueous solution containing H2O2. The selectivities of these products at the maximum of tartaric acid were 71, 4, and 2% at H2O2 feeding rate of 3.2 ml h-1, respectively. On the other hand, the irradiation of maleates such as dipotassium, calcium, and disodium greatly enhanced the selectivities of tartaric acid formation to 19%, and of malic acid formation to 13%, respectively, for dipotassium maleate. It may be considered from these results that the stability of the hydroxylated intermediate radical plays an important role for the efficient formations of tartaric and malic acids. (author)