Ravleen Kaur
Six membered heterocyclic aromatic compounds are more stable than five membered counterparts. In the case of alicylic heterocyclic compounds six membered rings are more stable than five and four membered rings. Six membered ring compounds stability can be attributed to the puckered nature of the rings, that eliminates the ring strain imparting more stability to the compounds. Five membered rings do have such stabilising factors, but not equal to that of six membered counter parts. Four and three membered rings do not have such stability because they are planar and the atoms experience severe strain.
