3,5-Dihydroxybenzoic Acid → 3,5-Diacetoxybenzoic Acid

HRID 1614281Notes

Reaction equation

HRID 1614281 reaction equation
[OH:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([OH:11])[CH:10]=1)[C:5]([OH:7])=[O:6]>C(OC(=O)C)(=O)C>[C:2]([O:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([O:11][C:5](=[O:6])[CH3:4])[CH:10]=1)[C:5]([OH:7])=[O:6])(=[O:1])[CH3:10]

Participants

3

Reactant 1

HCID 74243,5-Dihydroxybenzoic Acid

Product 1

HCID 5398693,5-Diacetoxybenzoic Acid

Reagents, catalysts & solvents 1

HCID 7918Acetic AnhydrideSolvent

Procedure

3,5-Dihydroxybenzoic acid (77grams, 0.5 mole) and 200 milliliters of acetic anhydride were mixed in a five hundred milliliter round-bottomed flask, which was fitted with a reflux condenser. As the mixture was heated to reflux the dihydroxyacid went into solution. Refluxing was continued for a total of 5 hours. A brown solution was obtained. Excess acetic anhydride was removed by rotary evaporation and the remaining solid was dried under vacuum at 40° C. The solid was dissolved in about 200 milliliters of refluxing chloroform, filtered hot and then diluted with 70 milliliters of petroleum ether (bp 60°-80° C.). The compound crystallized overnight and was isolated by filtration and washed with a 1:1 mixture of petroleum ether and chloroform. The compound was then recrystallized by the same procedure. Yield was 59 grams (50%) of white crystals. Melting point was 157°-159° C. NMR conducted as in the preceeding preparation, but using (DMSO-d6) gave as peaks, in ppm: 2.1 (s,6H), 7.23 (s, 1H), 7.55 (s, 2H), 13.3 (b, 1H).

Workup

  1. customwhich was fitted with a reflux condenser
  2. temperatureAs the mixture was heated
  3. temperatureto reflux the dihydroxyacid
  4. temperatureRefluxing
  5. customwas continued for a total of 5 hours
  6. customA brown solution was obtained
  7. customExcess acetic anhydride was removed by rotary evaporation
  8. customthe remaining solid was dried under vacuum at 40° C
  9. dissolutionThe solid was dissolved in about 200 milliliters of refluxing chloroform
  10. filtrationfiltered hot
  11. additiondiluted with 70 milliliters of petroleum ether (bp 60°-80° C.)
  12. customThe compound crystallized overnight
  13. customwas isolated by filtration
  14. washwashed with a 1:1 mixture of petroleum ether and chloroform
  15. customThe compound was then recrystallized by the same procedure
  16. customNMR conducted as in the preceeding preparation
  17. customgave as peaks, in ppm

Sources & evidence

ORD record
ord-974ec7c8da1548a2a7e66e2af5191a4c
Source dataset
uspto-grants-1993_03
Patent number
US05196502

Reaction notes

Loading…