Rate constants for reactions of perhaloalkylperoxyl radicals with alkenes

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100128a015· OSTI ID:5065812

Alfassi, Z B; Huie, R E; Neta, P ^[1]

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1. National Inst. of Standards and Technology, Gaithersburg, MD (United States)

Trichloro- and tribromomethylperoxyl radicals were produced by radiolytic reduction of CCl[sub 4] and CBr[sub 4] in various aerated solvents. Rate constants for the reactions of these radicals with unsaturated organic compounds were determined in methanol solutions by competition kinetics, using mainly chloropromazine as a reference. The rate constants were in the range k = 10[sup 4]-10[sup 7] L mol[sup [minus]1] s[sup [minus]1], and a good correlation was obtained between log k and the Taft substituent constants [sigma]*. Steric effects were also noticeable in some cases. The reactivities of the radicals were in the order CBr[sub 3]O[sub 2][center dot] < CCl[sub 3]O[sub 2][center dot] < C[sub 4]F[sub 9]O[sub 2][center dot], which is in contrast with the order observed in electron-transfer reactions. The rate constants for reaction of CCl[sub 3]O[sub 2][center dot] with 2,3-dimethyl-2-butene (DMB) and cyclohexene (CH) were studied in 12 solvents. In all cases DMB is considerably more reactive than CH, indicating that at least in the case of DMB the reaction is predominantly via addition. The rate constant for addition of CCl[sub 3]O[sub 2][center dot] to DMB varies by a factor of 7 in the different solvents. No correlation was found between these rate constants and thermodynamic or polarity parameters of the solvents, although viscosity appears to have an effect. 19 refs., 2 figs., 2 tabs.

• OSTI ID: 5065812
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:26; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
AIR POLLUTION
ALKENES
ATMOSPHERIC CHEMISTRY
CARBON TETRACHLORIDE
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
DECOMPOSITION
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
KINETICS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
POLLUTION
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS
REDUCTION
SOLVENTS
SYNTHESIS
THERMODYNAMICS