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Abstract:
The acid-catalyzed ring-opening reaction
of styrene oxide was used as a probe reaction for evaluating the acidic properties of carboxylated carbocatalysts.
Significant discrepancies in the initial reaction rates were normalized using the
total number of carboxyl groups, and demonstrated that the average catalytic
activities of the carboxyl moieties on
the carbocatalysts differed. Comparisons
between the apparent activation energy
Ea and the pre-exponential factor A, derived from Arrhenius analysis, demonstrated that A varied more significantly, and therefore had a more significant effect on the reaction rates than
Ea. The variation in the calculated pKa values of the carboxyl groups was attributed to the electronic effects of the nitro groups. This hypothesis was supported by the temperature programmed desorption profiles of nitrogen monoxide ions.
