ISOMERIZATION-REACTIONS OF 1,1,2,2-TETRAFLUOROETHANE - A KINETIC AND MECHANISTIC STUDY

Kinetic and mechanistic studies of the isomerization reactions of 1,1, 2,2-tetrafluoroethane to 1,1,1,2-tetrafluoroethane on conditioned chro mia were carried out. In contact with the surface of the solid 1,1,2,2 -tetrafluoroethane undergoes a separation of HF, forming noticeable am ounts of the olefin trifluoroethylene. Due to rearrangement of the ads orbed gas molecules in the surface, HF is re-added, forming 1,1,1,2-te trafluoroethane according to the Markovnikov rule. CHF2-CHF2 reversibl e arrow CHF=CF2 + HF CHF=CF2 + HF reversible arrow CH2F-CF3 A mathemat ical adjustment was carried out in order to describe the reaction mech anism. Modelling of the isomerization reaction suggests that the best agreement between the experimental and the calculated data can be achi eved when the decomposition of CHF2-CHF2 to HF and CHF=CF2 is consider ed to be reversible. The experimentally determined values of rate cons tants indicate a significant influence of the adsorption equilibria on these reactions. (C) 1995 Academic Press, Inc.