The mechanism of the Fischer esterification was controversial until 1938, when Irving Ro...

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 isotope of oxygen.

After a short period, the acid was neutralized to stop the reaction, and the components of the

mixture were separated.

(a) Propose a mechanism for this reaction.

(b) Follow the labeled ¹⁸O atom through your mechanism, and show where it will be found

in the products.

(c) The ¹⁸O isotope is not radioactive. Suggest how you could experimentally determine the

amounts of ¹⁸O in the separated components of the mixture.