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The initial rate of reaction between cyclopropane and hydrogen over a pumicesupported palladium catalyst is proportional to [H2]X[C&]Y, where x increases from -0.8 at 50" C to zero at 200" C, and y increases from 0.4 to 1.0 in the same temperature range. The reaction of cyclopropane with deuterium leads chiefly to the formation of deuteropropanes whose relative abundance is unaffected by changing either the initial reactant ratio or temperature. The use of a large excess of deuterium is necessary to dilute hydrogen and HD formed by exchange processes. The propane distribution is highly unsymmetrical, propanes-ds and -d7 accounting for some 80 % of the total.The distribution is interpreted in terms of two random redistributions of pools of H and D atoms of differing deuterium content, together with a small amount of direct addition.The reaction of propane with deuterium between 100 and 200" C produces deuteropropanes distributed in a similar manner, but the relative extents of the two random redistributions are temperature dependent. It is concluded that this difference in behaviour reflects a difference only in the initiating steps, and that the two contributing distributions arise in each case from reactions on different crystal faces of the metal.

Initial propane distributions from the reaction of cyclopropane with deuterium over a platinum catalyst have been obtained at 50, 100 and 200" C, and the results compare well with those of a previous study. Initial distributions from the reaction of propane with deuterium over platinum at temperatures between 100 and 250" C are similar. In both cases, the deuterium content and the proportion of the contributing distribution which is predominant at high temperatures are temperature dependent.A brief comparative discussion of the behaviour of rhodium, palladium, iridium and platinum in these reactions is given. It is concluded that efficiency in multiple exchange runs parallel with catalytic activity for hydrogenation-type reactions, and that in group 8 metals horizontal relationships are more marked than vertical relationships.

The reaction between cyclopropane and deuterium has been studied over a rhodium catalyst between 0 and 200" C, and initial propane distributions obtained. These can be interpreted as the sum of two random redistributions of pools of H and D atoms, together with a small amount of direct addition. The values of the parameters which reproduce the observed distributions are very similar to those recorded for palladium in part 1 ; they are independent of temperature. Propane exchange has been studied between 50 and 200" C over rhodium, and in this system a third random redistribution is needed to describe the observed initial distributions. The deuterium contents of the two major distributions are the same for both reactants, but their relative amounts are temperature dependent in the propane system.Between 15 and 100" C, the reaction between cyclopropane and deuterium over iridium yields propanes distributed much as over rhodium : the same is aIso true for the propane + deuterium reaction over iridium between 100 and 200" C. However, the ratio of the amounts of the two chief distributions over this metal is slightly temperature dependent in both cases. At 50" C the cyclopropane + hydrogen reaction is zero order in hydrogen, and the cyclopropane order is about one-half: the activation energy is 9.8 kcal/mole.

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