THE REACTION OF ETHANOL VAPOR WITH Hg 6(3P1) ATOMS

Abstract

The reaction of ethanol vapor with Hg 6(3P1) atoms has been investigated under static conditions at 25 °C. To determine the nature and efficiency of the primary process, the reaction has been studied in the presence of nitric oxide, and also under conditions of inter mittent illumination. For the pure substrate the volatile products were H2 (0.53), CH3CHO (0.08), CO (0.025), C2H6 (0.006), and CH4 (0.002), with the bracketed numbers representing the quantum yields at zero exposure time. The heavy product was a mixture of butanediols containing 90% 2,3-, 8% 1,3-, and 2% 1,4-butanediol. With 20% added NO, the products were EtONO (0.25), N2O (0.14), H2O, and H2 (0.017). Under intermittent illumination, the quantum yield (Φ) of H2 formation for pure substrate was measured as a function of the light period (tL) and the dark period (tD). For maximum values of Φ(H2), it was found that tD had to exceed ca. 120 msec. Under these conditions, Φ(H2) rose linearly with decreasing log tL, to a maximum value of 0.96 at tL less than 0.4 msec.From the study it is concluded that ethanol reacts with Hg 6(3P1) atoms to form ethoxy radicals and H atoms with at least 96% efficiency. The primary ethoxy radicals disappear by hydrogen abstraction from the substrate to form mainly CH3CHOH radicals. Under continuous illumination the low value (0.53) for Φ(H2) is caused principally by the addition of H atoms to the CH3CHOH radicals.