MATRIX EFFECTS IN THE LOW-TEMPERATURE OZONATION OF ETHYLENE, TETRAMETHYLETHYLENE AND 1-HEXENE

The ozonation of the title compounds was studied in argon and CO2 matr ices at low temperatures (12-80 K). All three were found to react with ozone in a CO2 matrix deposited at low temperature, and having an amo rphous structure. The reaction was found to start at 26 K, the tempera ture at which the matrix undergoes a phase transition. In contrast, on ly tetramethylethylene (TME) was found to react in an argon matrix, th e other two compounds remaining inactive towards ozone up to the softe ning temperature of argon (similar to 40 K). These results are interpr eted as indicating that reaction between olefins and ozone is initiate d at low temperatures once the two reactants are free to move to the r equired configuration. This idea is supported by molecular dynamics si mulations on the TME reaction. The infrared spectra of the primary ozo nide of TME, as well as of the primary and secondary ozonide of l-hexe ne are reported, and compared with quantum chemical calculations. (C) 1998 Elsevier Science B.V.