n120447SE Academic Article uri icon

abstract

  • Potassium-graphite, a typical alkali metal-graphite intercalation compound, has been found to undergo reactions with organic substrates by both one- and two-electron processes. The reaction of weak protic acids like water and alcohols with C8K proceeds both by simple deprotonation of the protic acid by the Lewis base C8K to give a partially reduced graphite and by reduction leading to hydrogen formation. ESCA spectra of the graphite product of these reactions, titrations of soluble base in these reactions of C8K and proton sources, and measurement of the amount of hydrogen evolved on reaction of C8K and an alcohol all suggest that the reactivity of C8K toward proton acids is substrate size dependent. In general, Lewis base abstraction of a proton by C8K seems to be more important with smaller alcohols. One-electron processes may be relatively more important in reactions of larger alcohols at the surface or edges of C8K. The acid-base chemistry of rubidium-graphite and cesium-graphite was shown to be similar to that observed for C8K. Study of products formed on reaction of alkyl halides with C8K show that one-electron transfer is an important reaction pathway for reductions with potassium-graphite. Characteristic radical rearrangements observed in the reduction of 5-hexenyl halides provided positive evidence for the intermediacy of free radicals. Attempts to trap carbanionic intermediates or alkylpotassium species with magnesium bromide were unsuccessful. However, transient carbanionic species or alkyl halide radical anions may have been present since reduction of tetrahydrofur-fural chloride with CgK led to the rearranged product, penten-5-ol. Typical products observed in reductions of alkyl chlorides were alkanes. Alkyl iodides reacted with C8K to give Wurtz coupled products. Alkyl bromides had reactivity patterns intermediate between that of alkyl chlorides and alkyl iodides. Other substrates were also briefly examined and the reductions observed in these cases generally correlated well with known chemistry of soluble aromatic radical anions like sodium naphthalene. The usefulness of potassium-graphite as a polymeric reagent was evaluated. 1978, American Chemical Society. All rights reserved.

published proceedings

  • Journal of the American Chemical Society

author list (cited authors)

  • Bergbreiter, D. E., & Killough, J. M.

publication date

  • January 1, 1978 11:11 AM