Nucleophilic Acyl Substitution (Carboxylic Acid Derivatives)

Problem # 730

N,N-dimethylformamide (DMF) is shown below. Based on its structure, you might expect to see only one -CH3 signal in the 1H NMR spectrum. But instead DMF shows two different -CH3 signals. Explain.

Problem # 729

The ester below was dissolved in a solution of water, a small amount of which was isotopically labeled with O-18, denoted with an asterisk.

After a few hours, some isotopically labeled oxygen was found in the ester. Where was it found in the ester? Can you explain why?