Chemistry Forum

Hi guys and girls,

I am reading a paper about Thiol-epoxy reaction kinetics with and without the usage of DABCO. For the reaction without DABCO they used a temperature of 160 degrees celsius and the calculated activation energy of the Reaction was 64 +/- 2 kJ mol-1. With DABCO they used an oven Temperature of 60 degrees celsius and the calculated activation energy was 71 +/- 2 kJ mol-1. I always thought that a catalyst lowers the needed activation energy. Is the activation energy dependent on the Temperature, i dont think so. Why is there an increase of the activation energy but at the same time a decrease of the needed Temperature?

And one more Information after the usage of DABCO the kinetic order went from 3 to 2.

Is the activation energy dependent on the Temperature, i dont think so.

No, it is dependent.
As temperature increases, molecules gain energy and move faster and faster. Therefore, the greater the temperature, the higher the probability that molecules will be moving with the necessary activation energy for a reaction to occur upon collision.

The both values cannot be compared.

160 °C 64 +/- 2 kJ mol-1 w.o. catalyst

60 °C 71 +/- 2 kJ mol-1 with catalyst.

Missing are values of activation energy at 160 ° C with catalyst.

Only what can be said is that the reaction takes place as lower temperature.