ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The stopped-flow measurements on the disappearance of alkaline osmium(VIII) at 402 nm indicated a first-order dependence each in [Os(VIII)] and [HCHO]. The pseudo first-order rate constant kobs ([HCHO] ≫ [Os(VIII)]) decreased with increasing [OH-]. The ionic strength, however, had no effect on kobs. The rapid scan spectra of the reaction mixture indicated the formation of an inert complex which absorbs at 319 nm. Therefore the rate determining step is considered to involve the bimolecular collision between OsO4(OH)22- and hydrated formaldehyde. The values of the rate limiting constant k and the equilibrium constant Kha for the formation of the alkoxide ion from the reaction of hydrated formaldehyde with OH- are evaluated. The equilibrium constant Kha, within the experimental limits, is independent of temperature. The pKa value, calculated from Kha, is 13.62 ± 0.05 which is in good agreement with the pKa value 13.27 for formaldehyde. The activation parameters, ΔH
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550230504
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