REACTIONS OF OXYGEN ATOMS WITH ACETYLENE

Ground-state oxygen atoms, generated by the mercury-sensitized decomposition of N2O, have been reacted with C2H2. Products include CO, C3H4, H2, and a polymer. The formation of C3H4 demonstrates that CH2 is generated in this system. However, the maximum CO yield accounts for only half of the oxygen atoms so that the reaction O + C2H2 → CH2 + CO cannot be the exclusive primary step. The dependence of the hydrogen yield on acetylene pressure suggests that most of the H2 comes from hydrogen atoms. Under conditions where most of the hydrogen atoms are being scavenged, a small H2 yield remains. Experiments with mixtures of C2H2 and C2D2 demonstrate that the reaction O + C2H2 → H2 + C2O occurs to a small extent. The possibility of a relative long-lived (C2H2O)≠ complex is suggested to account for the large amount of oxygen lost to the polymer. It is concluded that all of the reactions which are energetically possible do occur.