Chapter 20.10, Problem 20.16P

The mechanism of the Fischer esterification was controversial until 1938, when Irving Roberts and Harold Urey of Columbia University used isotopic labeling to follow the alcohol oxygen atom through the reaction. A catalytic amount of sulfuric acid was added to a mixture of 1 mole of acetic acid and 1 mole of special methanol containing the heavy ¹⁸O isotope of oxygen. After a short period, the acid was neutralized to stop the reaction, and the components of the mixture were separated.

1. a. Propose a mechanism for this reaction.
2. b. Follow the labeled ¹⁸O atom through your mechanism, and show where it is found in the products.
3. c. The ¹⁸O isotope is not radioactive. Suggest how you could experimentally determine the amounts of ¹⁸O in the separated components of the mixture.