Esterification and Ester Hydrolysis Worked Examples Cheat Sheet

Key Facts

• Fischer esterification follows the general reaction $\mathrm{RCOOH + R'OH \rightleftharpoons RCOOR' + H_2O}$ under acid catalysis.
• An acid catalyst such as $\mathrm{H_2SO_4}$ increases the reaction rate but is not consumed in the overall esterification reaction.
• Fischer esterification is reversible, so removing $\mathrm{H_2O}$ or using excess alcohol shifts equilibrium toward ester formation by Le Châtelier's principle.
• Acid hydrolysis of an ester follows $\mathrm{RCOOR' + H_2O \rightleftharpoons RCOOH + R'OH}$ and is the reverse of Fischer esterification.
• Base hydrolysis, or saponification, follows $\mathrm{RCOOR' + OH^- \rightarrow RCOO^- + R'OH}$ and is usually effectively irreversible because a carboxylate ion forms.
• For esterification stoichiometry, the mole ratio between carboxylic acid and alcohol is usually $1:1$, so $n=\frac{m}{M}$ is used to find the limiting reactant.
• Percent yield is calculated with $\%\text{ yield}=\frac{\text{actual yield}}{\text{theoretical yield}}\times 100\%$.
• The ester name is built from the alcohol part first as an alkyl group, followed by the carboxylic acid part ending in $\text{-oate}$.

Vocabulary

Ester

An ester is an organic compound containing the functional group $\mathrm{RCOOR'}$.

Fischer esterification

Fischer esterification is the acid-catalyzed reaction of a carboxylic acid with an alcohol to form an ester and water.

Hydrolysis

Hydrolysis is a reaction in which water breaks a bond, such as converting an ester into a carboxylic acid and an alcohol under acidic conditions.

Saponification

Saponification is base hydrolysis of an ester that produces a carboxylate salt and an alcohol.

Equilibrium

Equilibrium is the state in a reversible reaction where the forward and reverse reaction rates are equal.

Limiting reactant

The limiting reactant is the reactant that is used up first and determines the maximum amount of product that can form.