Rapid hydration of the acetyl radical. A pulse radiolysis study of acetaldehyde in aqueous solution
In aqueous solution acetaldehyde and its hydrate are in a 0.8:1 equilibrium. Hydroxyl radicals generated by the pulse radiolysis of N/sub 2/O-saturated water react with this mixture with an overall rate constant of k = 2.4 x 10/sup 9/ dm/sup 3/ mol/sup -1/ s/sup -1/, the rate of reaction with acetaldehyde being about 3 times faster than with the hydrate. The predominant radicals formed are the acetyl radical and its hydrated form, H-abstraction at methyl occurring to only about 5-10%. The acetyl radical rapidly hydrates with its rate of hydration being 2 x 10/sup 6/ times faster than that of the parent compound acetaldehyde. The hydrated acetyl radical has been monitored by its rapid reduction of tetranitromethane the formation of /sub 2//sup .-/ in the presence of oxygen, and its deprotonation at pH 11 (pK/sub a/ /<=/ 9.5). The acetyl radical does not oxidize N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) at the pulse radiolysis time scale, but the acetylperoxyl radical (formed in the presence of oxygen) reacts rapidly with TMPD, ascorbate, and O/sub 2//sup .-/ and hence is the most strongly oxidizing peroxyl radical known so far. Data on the rate of water loss from the hydrated acetyl radical are considerably less accurate, but it may well be that this reaction has a rate constant of k/sub 10/ /approx equal/ 3 x 10/sup 4/ s/sup -1/. 24 references, 3 figures, 1 table.
- Research Organization:
- Max-Planck-Institut fuer Strahlenchemie, Muelheim a.d. Ruhr (West Germany)
- OSTI ID:
- 6083241
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:17; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400600* -- Radiation Chemistry
ACETALDEHYDE
ALDEHYDES
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
DISPERSIONS
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROXYL RADICALS
INFORMATION
MIXTURES
NITROGEN COMPOUNDS
NITROGEN OXIDES
NITROUS OXIDE
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
SOLUTIONS
WATER