Hydrogen peroxide, acid dissociation constant

It is worth mentioning that an attempt was made by Tsao and Willmarth to determine the acid dissociation constant of HO2. The reaction between hydrogen peroxide and peroxydisulphate was used for the generation of the HO2 radical. However, these experiments, like others where the HO2 radical is studied under steady-state conditions, could yield only a value of acidity constant multiplied by a coefficient consisting of a ratio of kinetic parameters. Unfortunately, in this case there are no independent data for the kinetic coefficient, and the value of cannot be evaluated. Considering the kinetic analogue of the titration curve it can be stated only that ionization of HO2 becomes important in the pH range from 4.5-6.5. The value of acidity constant of HO2 obtained by Czapski and Dorfman is (3.5 + 2.0)x 10 mole.l. . ... 

Hydrogen peroxide is a somewhat stronger acid than water, and in dilute aqueous solutions has p a(25°) = 11.65 0.02, i.e. comparable with the third dissociation constant of H3PO4 (p. 519) ... 

Irradiation of an aqueous solution at 296 nm and pH values from 8 to 13 yielded different products. Photolysis at a pH nearly equal to the dissociation constant (undissociated form) yielded pyrocatechol. At an elevated pH, 2-chlorophenol is almost completely ionized photolysis yielded cyclopentadienic acid (Boule et al., 1982). Irradiation of an aqueous solution at 296 nm containing hydrogen peroxide converted 2-chlorophenol to catechol and 2-chlorohydroquinone (Moza et al, 1988). In the dark, nitric oxide (10 vol %) reacted with 2-chlorophenol forming 4-nitro-2-chlorophenol and 6-nitro-2-chlorophenol at yields of 36 and 30%, respectively (Kanno and Nojima, 1979). 

Hydrogen peroxide exhibits a weak acidic character, having a dissociation constant of about 1.5 x 10 l2 thus, pure aqueous solutions of hydrogen peroxide have pH values below 7. The dissociation constant of hydrogen peroxide is 10 ... 

Poly(acrylhydroxamic acid)-Cu(II) complex has a high catalytic activity in the decomposition reaction of hydrogen peroxide. From the comparison of complex formation constants (stabilization constants) both in the polymer and the low molecular weight molecule, it was considered that the high activity is owed to a partly dissociated or a solvent coordinated moiety (104,105). Poly(methacryloylacetone)-Cu(II) complex is also investigated (108). 

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