Stereochemical studies. XI. Equilibria between δ-hydroxy-acids and δ-lactones in aqueous tetrahydrofuran. Relative stabilities of isomeric δ-lactones

Article abstract of DOI:10.1139/v82-367

The equilibrium constants K' for the hydrolysis of 13 δ-lactones to hydroxy-acids in 54percent (mol/mol) aqueous tetrahydrofuran at 25 deg C have been determined.The equilibrium constants for the isomerization of the five δ-lactones into their epimers, and for the isomerization of their hydroxy-acids into their epimers, have been calculated by the methods of conformational analysis.These calculated values are consistent with the experimental values of K'.Addition of methyl groups to a hydroxy-acid decreases K' (the Thorpe-Ingold effect).