An ester forms from a carboxylic acid and an alcohol.

This reaction is superficially similar to the reaction of an acid with a base such as sodium hydroxide. The mechanism of the reaction can be followed by using the tracer ¹⁸O. This isotope is not radioactive, but other physical measurements can be used to detect its presence. When the esterification reaction is carried out with the alcohol containing oxygen-18 atoms, no oxygen-18 beyond its naturally occurring abundance is found in the water produced. How does this result affect the perception that this reaction is like an acid–base reaction?

Transcribed Image Text:

RCO₂H + HOR' RCO₂R' + H₂O