The saponification of 18O-labeled ethyl propanoate was described in Section 20.10 as one of the significant experiments that demonstrated acyl–oxygen cleavage in ester hydrolysis. The 18O-labeled ethyl propanoate used in this experiment was prepared from 18O-labeled ethyl alcohol, which in turn was obtained from acetaldehyde and 18O-enriched water. Write a series of equations showing the preparation ofCH3CH2COCH2CH3 (where O = 18O) from these starting materials.