Changes in the hydrogenative ring-opening mechanism of cyclohexene oxide over Cu/SiO2 resulting from the addition of cyclohexene, a major product

The ring-opening mechanism influencing effect of a major product in the cyc lohexene oxide-D-2 system was investigated over a Cu/SiO2 catalyst. This pr oduct is cyclohexene, thus, the hydrogenative ring opening of a 1:1 cyclohe xene oxide-cyclohexene mixture was studied in the presence of D-2 at 403 K in a closed circulation reactor. It was found that the mechanism of single C-O scission was not affected, but that of the double C-O scission was chan ged. Simultaneous bond cleavage was the major route of ring opening in the additive-free system and it became consecutive on cyclohexene addition. Add ed cyclohexene was hydrogenated with a very low rate, but it transformed th e surface of the catalyst and, thus, facilitated the change in the mechanis m. An explanation concerning the seemingly anomalous lack of deuterium in a product (cyclohexane) not seen in the additive-free system is also suggest ed.