Sodium phenoxide is heated with $\mathrm{CO}{}_2$ at 4-7 atm and about 400 K, and the product is then acidified with $\mathrm{H}{}_3\mathrm{O}{}^{+}$. The main product is

This is the Kolbe-Schmidt reaction. The weak electrophile $\mathrm{CO}{}_2$ attacks the phenoxide ion at the ortho position under these conditions, giving sodium salicylate. Acidification liberates salicylic acid, 2-hydroxybenzoic acid.