Question

An ester has the molecular formula `C_(4)H_(8)O_(2)`. Write its structural formula, what happens when this ester is heated in the presence of sodium hydroxide solution? Write the balanced chemical equation for the reaction and name the products. Wha si a saponification reaction?

Answer 1

For the molecular formula `C_(4)H_(8)O_(2)`, Two isomeric esters are possible which differ in structural formulae. These are
`underset("Ethyl ethanoate "(C_(4)H_(8)O_(2)))(CH_(3)-overset(O)overset(||)(C)-OC_(2)H_(5))" and "underset("Methyl propanoate "(C_(4)H_(8)O_(2)))(C_(2)H_(5)-overset(O)overset(||)(C)-OCH_(3))`
Both will react with sodium hydroxide upon heating to form the sodium salt of the acid and alcohol.
`underset("Ethyl ethanoate")(CH_(3)-overset(O)overset(||)(C)-OC_(2)H_(5))+NaOHoverset(Heat)tounderset("Sod. ethanoate")(CH_(3)-overset(O)overset(||)(C)-ON a)+underset("Ethanol")(C_(2)H_(5)OH)`
`underset("Methyl propanoate")(C_(2)H_(5)-overset(O)overset(||)(C)-OCH_(3))+NaOHoverset(heat)tounderset("Sod. propanoate")(C_(2)H_(5)-overset(O)overset(||)(C)-ONa)+underset("Methanol")(CH_(3)OH)`
Both the reaction are the examples of saponification reactions. IN these, a ester reacts with an alkali upon heating to form corresponding salt and alcohol.