Rate constants for the reactions t-C sub 4 H sub 9 + DX yields i-C sub 4 H sub 9 D + X (X = Br, I), 295 < T(K) < 384: Heat of formation of the tert-butyl radical
Journal Article
·
· Journal of the American Chemical Society; (USA)
- SRI International, Menlo Park, CA (USA)
Absolute values for the rate constants of the metathesis reactions of DX (X = Br, I) with tert-butyl, generated by 351-nm photolysis of 2,2{prime}-azoisobutane, were determined in a low-pressure Knudsen cell reactor using the VLP{Phi} (very low pressure photolysis) technique. For X = Br, the values are 10{sup {minus}8}k (M{sup {minus}1} s{sup {minus}1}) = 0.9 and 2.3, and for X = I the values are 2.1 and 3.1 at 295 and 384 K. The latter are in good agreement with earlier measurements from this laboratory. The former values are lower by a factor of 50 compared to those recently reported at 295 K and fail to show the negative activation energy found in that work. Correcting by {radical}2 for the primary isotope effect and combining with the rate constants for the reverse reactions lead to {Delta}H{sub f}{degree} {sub 298}(tert-butyl) (kcal mol{sup {minus}1}) = 9.2 {plus minus}0.5 in both cases. First-order heterogeneous loss of tert-butyl radicals on the Teflon-coated surface employed is small (< 2 s{sup {minus}}1). 17 refs., 9 figs., 3 tabs.
- DOE Contract Number:
- FG03-86ER13571
- OSTI ID:
- 5050569
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:3; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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· J. Phys. Chem.; (United States)
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OSTI ID:5698527
Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKANES
ALKYL RADICALS
BUTANE
BUTYL RADICALS
CHEMICAL REACTIONS
DATA
DEUTERIUM COMPOUNDS
ENTHALPY
EXPERIMENTAL DATA
FORMATION HEAT
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
RADICALS
REACTION HEAT
TEMPERATURE EFFECTS
THERMODYNAMIC PROPERTIES
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKANES
ALKYL RADICALS
BUTANE
BUTYL RADICALS
CHEMICAL REACTIONS
DATA
DEUTERIUM COMPOUNDS
ENTHALPY
EXPERIMENTAL DATA
FORMATION HEAT
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
RADICALS
REACTION HEAT
TEMPERATURE EFFECTS
THERMODYNAMIC PROPERTIES