Hydrogen atom abstraction by fluorine atoms

Abstract

The relative rates of abstraction of hydrogen atoms by 18F atoms have been measured for H2, D2, CH*, CD*, C2H6, CH3CF3, H2S, and HI vs. the rate of addition to acetylene. The measurements have involved the competitive diminution in yield of CH2=CH18F (from CH18F=CH + HI) vs. RH(or RD)/C2H2 ratio. The samples contained excess SFe which served both as the target for formation of 18F by the 19F(n,2n)18F nuclear reaction, and as the moderator for the excess recoil energy of these 18F atoms. The relative rates per H or D atom varied from 0.018 ± 0.004 for CH3CF3 to 0.65 ± 0.05 for H2S. The abstraction of H was favored over D for both isotopic pairs of molecules: for H2/D2 and for CH4/CD4. No reaction was observed for 18F with xenon.

A Review of Rate Coefficients in the H2-F2 Chemical Laser System

“…2 X 10 cc/mol-sec. This result for k. agrees well with those 5 4 • of jfoon and Reid (1971) and of Williams and Rowland (1973) but is a factor of 2.5 to 10 lower than most of the other determinations. Rabideau, Hecht, and Lewis (1972) gave no indication of the sensitivity of their result for k. to changes in their result for k,.…”

Computer Simulation Evaluating Kinetic Theory Parameters in Hot Atom Chemistry

“…Molecular diameter appeared to be the most sensitive parameter where small variations changed the yield from 0 to 100%. Our optimized radius for the model was 2.4 Â in good agreement with the experimental value of 2.1 Ä [40]. BUNKER and JACOBSON [35] simulated the radical recombination caging of iodine in carbon tetrachloride.…”

Semirigid vibrating rotor target model for atom-polyatom reactions: Application to F+CH4→CH3+HF

“…It is therefore interesting to investigate the resonance contribution to the computed F+CH 4 → FH+CH 3 crosssection in a little more detail. The most effective way is to combine the expected resonance contribution with the reaction probability at v =0 [40,41] .…”