摘要：Available chlorine in the aqueous solutions of variously chlorinated isocyanuric acids and isocyanuric acids with hypochlorous acid was separately determined for free and combined types by the utilization of difference in the reactivity of the free and combined types with the DPD method and neutral o-tolidine method. Reaction of the commercial isocyanuric acid in a high concentration with hypochlorous acid resulted in the formation of a combined chlorine but when isocyanuric acid repeatedly recrystallized from hot water was used, there was no formation of the combined chlorine. Isocyaunric acid obtained by evaporation of the recrystallization mother liquor formed a larger amount of combined chlorine than the original acid. These facts seem to indicate that the formation of combined available chlorine is due to impurities contained in commercial isocyanuric acid. In order to examine the reactivity of available chlorine in monochloroisocyanuric acid, its formation from isocyanuric acid by chlorination was attempted. Mass spectra were measured of chlorinated isocyanuric acids formed, with 18-79% chlorine content, and their structural components analyzed. Samples with high chlorine content consisted of trichloro compound and there was no peak of the monochloro compound. However, addition of isocyanuric acid to that sample resulted in the appearance of the peak of monochloroisocyanuric acid in its mass spectrum, in spite of the absence of the monochloro compound. In the samples with relatively low chlorine content, presence of isocyanuric acid and dichloroisocyanuric acid cannot be avoided, and the presence of monochloro compound in the sample could not be confirmed directly. The available chlorine in the chlorinated isocyanuric acids was measured as the free available chlorine, irrespective of its content. Free chlorine in chlorinated isocyanuric acid was preliminarily removed by boiling its solution and an aqueous solution containing ca. 500 ppm as isocyanuric acid was prepared. A solution of hypochlorous acid was then added for reaction with isocyanuric acid but there was no formation of the combined type chlorine. This fact also shows that impurities in isocyanuric acid have been removed by chlorination.
关键词：isocyanuric acid;monochloroisocyanuric acid;dichloroisocyanuric acid;trichloroisocyanuric acid;chlorination of isocyanuric acid;available chlorine
