Alcohol 3:
Propionaldehyde 2, the product of the oxidation, can react reversibly with the starting material 1, n-propyl alcohol, to form the hemiacetal 3. This situation is analogous to the hydration of an aldehyde during Jones' oxidation (see Problem 2 in Alcohols). Hemiacetal 3 is, after all, an alcohol. It can be oxidized to n-propyl propionate 4, an ester. Propionaldehyde 2 (bp. 49 oC) can be readily separated from the ester 4 (bp. 112 oC) by distillation. How can the formation of ester 4 be minimized?