Thermal F/X atomic substitution reactions with methyl halides (X = Cl, Br, I)

Journal Article · Thu Aug 20 00:00:00 EDT 1981 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150617a016· OSTI ID:6293077

Iyer, R S; Rowland, F S

The thermal substitution of F for X in CH/sub 3/X (X = Cl, Br, I) at 283/sup 0/K has been observed by using radioactive /sup 18/F atoms moderated to thermal energies by multiple collisions in gaseous SF/sub 6/ at 3000 torr. The relative rate constants for these reactions have been measured in competition with addition to C/sub 2/H/sub 2/ and/or abstraction from HI, and have been converted to absolute rate constants by assuming a rate constant of 1.5/sub 3/ x 10/sup -10/ cm/sup 3/ molecule/sup -1/ s/sup -1/ for F + C/sub 2/H/sub 2/. The rate constants for the thermal substitution of F/X in CH/sub 3/X increase as the exothermicity of the replacement reaction increases, and have the following rate constants at 283/sup 0/K, in units of cm/sup 3/ molecule/sup -1/ s/sup -1/: F + CH/sub 3/I ..-->.. CH/sub 3/F + I, k/sub 6/ = (8 +- 3) x 10/sup -13/; F + CH/sub 3/Br ..-->.. CH/sub 3/F + Br, k/sub 5/ = (1.7 +- 0.3) x 10/sup -13/; F + CH/sub 3/Cl ..-->.. CH/sub 3/F + Cl, k/sub 4/ = (3.7 +- 1.3) x 10/sup -14/. In each case the abstraction of H from CH/sub 3/X is very much faster than the substitution reactions.

• Research Organization: Univ. of California, Irvine
• DOE Contract Number: AT03-76ER70126
• OSTI ID: 6293077
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 85:17; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400701* -- Radiochemistry & Nuclear Chemistry-- Hot-Atom Chemistry
ACETYLENE
ALKYNES
ATOMS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BROMINATED ALIPHATIC HYDROCARBONS
CHEMICAL REACTION KINETICS
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
COMPARATIVE EVALUATIONS
FLUORIDES
FLUORINE 18
FLUORINE COMPOUNDS
FLUORINE ISOTOPES
HALIDES
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HOT ATOM CHEMISTRY
HOURS LIVING RADIOISOTOPES
HYDRIODIC ACID
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
IODINATED ALIPHATIC HYDROCARBONS
IODINE COMPOUNDS
ISOTOPES
KINETICS
LIGHT NUCLEI
MEDIUM PRESSURE
MEDIUM TEMPERATURE
METHYL BROMIDE
METHYL CHLORIDE
METHYL IODIDE
NUCLEI
ODD-ODD NUCLEI
ORGANIC BROMINE COMPOUNDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
RADIOCHEMISTRY
RADIOISOTOPES
REACTION KINETICS
RECOILS
SULFUR COMPOUNDS
SULFUR FLUORIDES