Kinetics of oxidation of vanadium(IV) by alkyl hydroperoxides in acidic, aqueous solution
- Iowa State Univ., Ames (United States)
The title reactions produce VO[sub 2][sup +] and products derived from [beta]-scission of alkoxy radicals, largely acetone, ethane, and methane (tert-butyl hydroperoxide) or ethane, ethylene, and n-butane (tert-amyl hydroperoxide). The minor amounts of methane from the first reaction and the excess amount of ethane from the second suggest a small contribution from the oxidation of VO[sup 2+] by [sm bullet]CH[sub 3] and [sm bullet]C[sub 2]H[sub 5], respectively. The kinetic dependence of the main reaction upon [H[sup +]] is consistent with the formation of an intermediate OVOOR[sup +] present at steady-state concentrations. This intermediate produces VO[sub 2][sup +] and RO[sm bullet] in a rate-limiting step. The yield of VO[sub 2][sup +] is stoichiometric in the t-AmOOH reaction, whereas only about half this amount of VO[sub 2][sup +] is produced from t-BuOOH. Although chloride ions affect neither reaction, Br[sup [minus]] changes the stoichiometry, products, and kinetics of the t-BuOOH reaction, but not those of the t-AmOOH reaction. These differences are accounted for by the relative reactivities of the intermediate alkoxy radicals, RO[sm bullet] toward [beta]-scission versus bromide oxidation. Addition of alcohols with [alpha]-H's (i.e., CH[sub 3]OH, C[sub 2]H[sub 5]OH, (CH[sub 3])[sub 2]CHOH) does not affect VO[sub 2][sup +] production from t-AmOOH but does prevent VO[sub 2][sup +] formation from t-BuOOH because VO[sub 2][sup +] is reduced by the alcohol radical formed in the reaction between t-BuO[sm bullet] and ROH. Several models are suggested, all of which feature [beta]-scission of t-BuO[sm bullet] and t-AmO[sm bullet]. The data pertaining to products and stoichiometry suggest an interaction or complexation of VO[sub 2][sup +] by t-BuOOH (but not t-AmOOH), which is supported by product yields, ion-exchange isolation, and spectroscopic evidence.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 7180981
- Journal Information:
- Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 31:10; ISSN 0020-1669; ISSN INOCAJ
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ACETONE
ALKANES
ALKENES
ALKOXY RADICALS
AQUEOUS SOLUTIONS
BROMIDES
BROMINE COMPOUNDS
BUTANE
CARBOXYLIC ACIDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DECOMPOSITION
DISPERSIONS
ELECTRON SPIN RESONANCE
ELEMENTS
ETHANE
ETHYLENE
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
ION EXCHANGE
KETONES
KINETICS
MAGNETIC RESONANCE
METALS
METHANE
MIXTURES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PERCHLORATES
PEROXIDES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
QUANTITY RATIO
RADICALS
REACTION KINETICS
RESONANCE
SOLUTIONS
TRANSITION ELEMENTS
VANADIUM