THE EXISTENCE OF THE FLEXIBLE CONFORMATION IN SIX-MEMBERED RINGS

Abstract

From consideration of electrical polarization and nuclear magnetic resonance measurements, 1,4-dimethylenecyclohexane and its exo-tetramethyl and tetraphenyl analogues have been assigned the flexible ring conformation, as have also 1,4-dithiane and cis-1,4-dithiane-1,4-dioxide. However, the magnitudes of the moments indicate that uniform flexibility is not prevalent, the stretched form being predominant. In contrast to these flexible forms the conformation of dithiane monoxide is thought to be chair and that of 2,5-diphenyl-1,4-dithiin a fixed boat.