Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid−Acetate Buffer

1997 ◽  
Vol 36 (7) ◽  
pp. 1338-1344 ◽  
Author(s):  
Edward T. Urbansky ◽  
Brian T. Cooper ◽  
Dale W. Margerum
1994 ◽  
Vol 39 (7) ◽  
pp. 917-920 ◽  
Author(s):  
Punit Parmananda ◽  
Howard D. Dewald ◽  
R.W. Rollins

1993 ◽  
Vol 71 (2) ◽  
pp. 167-174 ◽  
Author(s):  
M. Balón ◽  
P. Guardado ◽  
C. Carmona ◽  
J. Hidalgo ◽  
M. A. Munoz

A kinetic study is reported on the oxidation of diphenylamine (DPA) by peroxodisulfate (PDS) anions in H2SO4 and buffered acetic acid – acetate 20% v/v methanol–water media. The primary detectable product of the reaction is N-phenyl-p-benzoquinoneimine (PBQ), which undergoes acid-catalyzed hydrolysis giving different decomposition products. At pH > 4 (acetic acid – acetate buffers) the hydrolytic decomposition is very slow and it does not interfere with PBQ formation, but in H2SO4 media of pH < 2.5, PBQ decomposes as it is formed. In these media, the reaction obeys the kinetic rate law:[Formula: see text]a, the kinetic parameter, being acid dependent. Neither radical promoters (Ag+) nor radical traps (allyl alcohol) influence the reaction rate. In acetic acid – acetate buffers of pH > 4 the kinetic rate law is simple: first order in each one of the reactants, and acid independent. These results have been interpreted by assuming the formation, in a preequilibrium step, of an N-diphenylhydroxylamine-O-sulfonate intermediate, which further rearranges to yield PBQ. The rate-determining step of the reaction changes with the protonation state of the intermediate, whose protonation pKa has been kinetically estimated as 2.4.


1970 ◽  
Vol 49 (3) ◽  
pp. 621-625 ◽  
Author(s):  
Stephen H.Y. Wei

The electron microprobe was used to analyze the calcium and phosphorus concentrations of sound, acid-etched, and remineralized enamel. By use of a weak acetic acid-potassium acetate buffer, it was found that the demineralization probably affected only the first 10 micrometers of the enamel surface. This demineralized enamel was successfully remineralized by the use of a calcifying solution. The changes in calcium and phosphorus concentrations and the Ca/P ratios were determined.


1972 ◽  
Vol 94 (4) ◽  
pp. 1247-1249 ◽  
Author(s):  
R. S. Schwartz ◽  
H. Yokokawa ◽  
E. W. Graham

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