 When a bulky and polar solvent is able to interact with one of the substituents in the allylic group, the complex of the solvent can energetically force the bulky complex out of the allylic strain in favor of a smaller group.Conjugation increases the allylic strain because it forces substituents into a configuration that causes their atoms to be in closer proximity, increasing the strength of repulsive Van der Waals forces.This situation occurs most noticeably when carboxylic acid or ketone is involved as a substituent of the allylic group.