SOLVENT EFFECT IN PERICYCLIC-REACTIONS .8. THE RETRO CLAISEN REARRANGEMENT

The solvent effect on the retro Claisen rearrangement was kinetically investigated in 17 solvents. The rate constants were found to be a linear function of the Reichardt's E(T)(30) solvent polarity parameter. Tha rate was measured in 3 lithium perchlorate-methanol solutions, their E(T)(30) values determined, and the kinetic data found to lie on the previous linear relationship. Hence the solvent effect (as well as the activation parameters) of the retro Claisen rearrangement confirmed the nature of concerted reaction with a partial charge separation in the transition state, as previously demonstred for the forward process.