When salicylic acid is heated with methyl alcohol, the carboxyl group of salicylic acid is esterified producing a strong-smelling liquid ester (methyl salicylate). Aspirin is prepared by chemical synthesis from salicylic acid, through acetylation with acetic anhydride.

 Hence, reagent $\text{'}\mathrm{Y}\text{'}$ and $\text{'}\mathrm{X}\text{'}$ respectively are: ${\mathrm{CH}}_3\mathrm{OH}/{\mathrm{H}}^{+}, ∆$ and ${\left({\mathrm{CH}}_3\mathrm{CO}\right)}_2\mathrm{O}/{\mathrm{H}}^{+}$.