Recent Experimental Approaches to Skeletal Rearrangements

As discussed in Section IV, Barron et al. (55, 61) found the cyclic mechanism of isomerization to be predominant, perhaps the sole route, on a highly dispersed platinum-alumina (0.2% w/w Pt). The cyclic mechanism was shown to be important also over platinum films and supported platinum of moderate dispersion ( 100 A). Here, although the product distributions were very different from that found over the dispersed catalyst, the initial product distributions at 300°C were practically identical in the isomerization and in methylcyclopentane hydrogenolysis. At lower temperatures they were somewhat different as they also were at all temperatures on platinum films. It was suggested that, especially on platinum films, a bond-shift isomerization could accompany the cyclic 

Reaction of n-Hexane over Platinum Film Catalysts Reaction Products° b 

Film Average crystallite diam. (A) Initial hydro-genolysis rate (1012 molec. sec-1 cm-2) Steady hydro-genolysis rate (1012 molec. sec-1 cm-2) Products6 (mole %)  

Reaction rate per unit total area 19 7T-adsorbed s mechanism g -4 3.5 H 0.2 ip y n-odsorbed mechanisms 0.S H 0.4 

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