ALTERATION OF PRIMARY ALCOHOL REACTION PATHWAYS ON RH(111) - FLUORINATION BLOCKS OXAMETALLACYCLE FORMATION

Temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) studies of 2,2,2-trifluoroethanol on Rh(111) were performed in order to determine if the oxametallacycle-mediated pathway for ethanol decarbonylation could be circumvented by replacement of H with F at the beta-carbon. Reaction of 2,2,2-trifluoroethanol produced trifluoroacetyl fluoride, CO, HF, and H-2. Trifluoroacetaldehyde could also be desorbed as a product of trifluoroethanol decomposition under certain conditions; the observation of this product and of trifluoroacetyl fluoride indicates that aldehyde and acyl intermediates, rather than metallacycles, are formed in the course of this reaction. These results demonstrate that oxametallacycle formation from alcohols on Rh(111) can be blocked by complete substitution at the beta-carbon.