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0 °C

To a solution of 3,5-dihydroxybenzoic acid (7.71 g, 50 mmol) in EtOAc (110 mL) were added acetic anhydride (12.25 mL, 130 mmol) and pyridine (8.08 mL, 100 mmol) in an ice-water bath under a nitrogen atmosphere. The mixture was stirred at 0° C. for 40 min and then stirred at ambient temperature for 4 h. 98% Formic acid (2.36 mL, 60 mmol) was added and the resulting mixture was stirred for 1 h. Then, it was poured into water and extracted with EtOAc. The organic phase was washed with water and brine, dried over Na2SO4, filtered, and evaporated in vacuo. Purification of the residue via recrystallization from n-heptane/EtOAc provided 3,5-diacetoxybenzoic acid (8.97 g, 75.3%) as white solid. Data are: 1H NMR (CDCl3, 300 MHz) δ 12.1 (bs, 1H), 7.73 (d, 2H), 7.21 (t, 1H), 2.32 (s, 6H); 13C NMR (CDCl3, 75 MHz) δ 170.4, 169.0, 151.2, 131.5, 121.3, 121.0, 21.2; mp=161-162° C.; HRMS (EI+) found 238.0475 M+, calcd 238.0477 for C11H10O6; Anal. Calcd for C11H10O6: C, 55.47; H, 4.23. Found: C, 55.62; H, 4.37.

1. stirringstirred at ambient temperature for 4 h
2. stirringthe resulting mixture was stirred for 1 h
3. extractionextracted with EtOAc
4. washThe organic phase was washed with water and brine
5. dry with materialdried over Na2SO4
6. filtrationfiltered
7. customevaporated in vacuo
8. customPurification of the residue
9. customvia recrystallization from n-heptane/EtOAc