Question

Which of the following products are obtained when 1 mole of acetic anhydride reacts with 1 mole of salicylic acid?
A.1 mole of acetylsalicylic acid and 1 mole of acetic acid
B.1 mole of acetylsalicylic acid
C.1 mole of methyl salicylate and 1 mole of acetic acid
D.1 mole of ethyl salicylate and mole of acetic acid

Answer 1

Hint: When acetic anhydride is reacted with salicylic acid, salicylic acid undergoes acetylation reaction. Acetylation is an electrophilic substitution reaction and occurs in the presence of a catalyst. In acetylation reaction, a hydrogen atom is substituted by an acetyl group.

Complete step by step answer:
In compounds, where the hydrogen atom replaced is that belonging to a hydroxyl group, the product obtained is an ester and acetic anhydride is the most commonly used acetylating agent for such a reaction.
The reaction takes place in the presence of an acid catalyst which in this case is concentrated sulphuric acid. The acid protonated the oxygen atom of the acetic anhydride molecule. This positive charge is transferred to the adjacent carbonyl carbon by resonance. The electron deficient carbon atom attacks on the nucleophilic phenolic hydroxyl group of salicylic acid. The intermediate form is then deprotonated and one molecule of acetic acid is detached from the molecule.
Thus, the products formed are one mole of acetyl salicylic acid and one mole of acetic acid by the reaction of one mole each of salicylic acid and acetic anhydride. Acetyl salicylic acid is also generally known as aspirin. This reaction is widely used for the production of aspirin.

Thus, the correct option is A.

Note:
Aspirin or acetylsalicylic acid is a commonly used drug used to cure mild to moderate pain and is recommended commonly for arthritic problems. Aspirin also helps in reduction of risk of transient ischemic attacks. It is also used as an anti-inflammatory drug and blood thinners.