Why is sulphuric acid needed as a catalyst in esterification reactions?Thorough explanation please! Thanks!

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ncchemist eNotes educator| Certified Educator

Esterification is the reacting of a carboxylic acid with an alcohol to produce an ester.  In order for this reaction to work, two things are required: removal of the water produced as a byproduct, and an acid catalyst.  Sulfuric acid is a fine source of protons as an acid catalyst.  When the alcohol hydroxyl group attacks the carbon of the carboxylic acid, a species called the tetrahedral intermediate initially forms.  A proton from the sulfuric acid helps to promote the formation of this intermediate species.  Once this intermediate is formed, it collapses to eliminate a water molecule and leave the newly formed ester product behind.  So the acid is needed as a catalyst to help the tetrahedral intermediate to form.