N.M.R. Experiments on Ketals Part I. Reaction Heat and Entropy of the Methyl Ketal Formation of Cyclohexanone, Cyclopentanone and Cyclobutanone

Abstract The methyl ketal formation is strongly exothermic (‐14,6 Kcal/mole) with cyclohexanone and moderately so with cyclopentanone (‐3,5 Kcal/mole) and with cyclobutanone (‐2,5 Kcal/mole). An exceptional low reaction entropy is noted for cyclohexanone (‐59 E.U.) and this is partly ascribed to the occurence of a high proportion of the twist conformation in cyclohexanone.