MECHANISM OF O(3P) ADDITION TO CONDENSED FILMS .2. PROPENE 1-BUTENE AND THEIR MIXTURES

The kinetics of O(3P) addition to condensed films of propene and 1-butene has been investigated at 90°K. The reaction rate was found to be independent of olefin concentration for both propene and 1-butene using propane as an inert diluent. Films containing mixtures of propene and 1-butene yielded mostly C3 products at high olefin concentration and approached a limiting value of about 1.6 for the C3/C4 product ratio at infinite dilution in propane. When C3D6 films were used, the ratio of carbonyl to epoxide was measurably less than that obtained with C3H6. The results are interpreted in terms of a model which depicts the olefin film to be a nearly perfect sink for O(3P) atoms. The primary process is assumed to be the formation of a triplet adduct which undergoes either ring closure to form the epoxide or an intramolecular migration of a hydrogen atom to produce a carbonyl compound. The latter exhibits the expected isotope effect when D is substituted for H in the olefin reactant. The behavior of propene-1-butene mixtures can be accounted for qualitatively by assuming that propene not only reacts more rapidly but diffuses more easily than does the 1-butene.