Journal of M olecular Catalysis, 46 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML (1988) 373 - 384 373 COMPUTER SIMULATION OF METATHESIS REACTIONS OF POLYALKENYLENES MICHAEL G. MARTL, KLAUS HUMMEL and FRANZ STELZER Institut fiir Chemische Technologie organischer Stoffe, Technische Universitiit, Stremay rgasse 16, A-801 0 Graz (Austria) Summary The catalyzed metathesis equilibration of oligoalkenylenes (model sub- stances for polyalkenylenes) is investigated by Monte Carlo simulation. The structure of the simulation program is described. The reaction starts with monodisperse linear oligomers. Reactive double bonds are selected by gen- eration of uniformly distributed random numbers. In the underlying model, a simplified carbene mechanism is assumed. Simulation examples show the reaction kinetics for the formation of chains of different lengths and rings of different sizes. The product distribution in the equilibrium is investigated for different chain lengths and varying ratios of catalyst to double bonds. For the case in which only chain products are formed, the results are com- pared to a theoretical distribution function. Possible applications of the simulation studies are discussed. Introduction In some olefin metathesis reactions, for example polymerization of cycloolefins or degradation of polyalkenylenes, ring/chain equilibria and molecular size distributions must be considered [ 11. The distributions result- ing in the metathesis polymerization of cycloolefins have often been in- vestigated [2, 31, but the determination of the fraction of large rings in a mixture with linear macromolecules sometimes appears difficult. The investi- gation methods employed, including low angle laser light scattering and the determination of end groups by means of i3C NMR, did not always provide unambiguous results. A number of other investigations dealt with the metathesis degradation of polyalkenylenes [4, 51. An analytical problem occurred in this case, such that only the first members of the homologous series of degradation products, present in larger percentages could be determined, whereas the possible error in the investigation method employed (gas chromatography) could be relatively high. 0304-5102/88/$3.50 0 Elsevier Sequoia/Printed in The Netherlands