High pressure relief of steric inhibition in ionogenic organic reactions

Abstract

The pressure effect is examined in an ionogenic reaction, the phosphine-catalyzed cyanoalkylation of acrylic nitriles by primary alcohols. The increase of rate constants with pressure is enhanced with increasing chain length of the alcohol and depends on steric constraints imposed by the substituting methyl group in the acrylic compound. The pressure effect is in line with a considerable electrostriction depending on steric hindrance to ionization. Pressure is confirmed as a favorable determining factor in sterically hindered reactions.

Keywords:

• Pressure activation
• Steric hindrance
• Electrostriction
• Cyanoalkylation

This paper is dedicated to the memory of J. M. Besson.