Kinetic and thermodynamic study of substituent effect on the Claisen rearrangement of para-substituted SI aryl ether: a Hammett study via DFT

In order to find the susceptibility of the Claisen rearrangement and next proton shift reaction of ally) aryl etherto the substiment effects in pan position, the kinetic and the:rmodynamie parameters are calculated at The33 LTP level using 6-3110. b asis set. The calculated activation energies for the rearrangements and protonshift reactions are around 3133 kcaUmol and 52.16 kcal/mol, nap.. lively. Negative values for the activationentropy confirm the concerted mechanign for the Claisen rearrangement and proton shift reaction. TheHammett p value of -1.3433 obtained in Claigen rearrangement. Negative Hammett p value indicate, that theelectron donating groups slightly increase the rate of Claisen rearrangement. Positive Hammett p value (2.5132)for proton shift reaction indicates that electron withdrawing coups increase the rate of reaciion.