The kinetics of oxidation of hydrogen peroxide by several compounds (XC1) containing chlorine in its +1 formal oxidation state have been determined. The rate law in each instance is -d[XCl]/di = £[XC1][H02-]. Rate constants at 25.0 °C are k = 4.4 X 107 M~' s~' for tm-butyl hypochlorite in 0.35 M tert-butyl alcohol (µ = 0.02 M), k = 1.5 X 106 M"' s"1 for 7V-chlorosuccinimide (µ = 0.10 M), and k < 1 M~' s~' for ethanolchloramine (µ = 0.10 M). Formation of molecular oxygen in its ' 8 electronic excited state was detected for hydroperoxide oxidation by tert-butyl hypochlorite and Nchlorosuccinimide. The results confirm a previously proposed mechanism which identifies hydroperoxide ion and hypochlorous acid as the reactants in the corresponding singlet oxygen generating reaction between these compounds. General mechanistic features, which should be widely applicable to reactions of this type, are discussed.
The rate constant for the energy pooling reactions O2(1Δ)+O2(1Δ)→O2(1Σ)+O2(3Σ) and O2(1Δ)+I(2P1/2)→O2(1Σ)+I(2P3/2), were studied in the temperature range between 200–400 K. The room temperature rate constant for the former reaction was found to be (2.7±0.4)×10−17 cm3 molecule−1 s−1 and for the latter reaction was found to be (8.2±1.6)×10−14 cm3 molecule−1 s−1 in reasonable agreement with the previous determination by other workers. The temperature dependencies of both reactions are small over the range of interest.
The performance of a sparger-type, singlet-delta-oxygen generator using various amines as alternative bases to NaOH was found to be comparable to the performance of a generator with the Cl2-NaOH-H2O2-H2O reactant system. Based on the percentage of singlet-oxygen evolution from the generator and the known rates of reaction between Cl2 and propylamine, the reaction between Cl2 and HO−2, which is assumed to produce singlet oxygen, is estimated to be ∼108 M−1 s−1.
The results of a study on improved methods for generating O2(1Δ) are presented. A wetted-column reactor utilizing C12 and a mixed H2O2-NaOH solution as reactants was found to produce 70–80 mmole/s of O2, [50% as O2(1Δ)], with a C12 input of 90–100 mmole/s.
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