2-Methylbenzenesulfonic acid → ortho-aminophenylbenzoxazole

HRID 848208Notes

Reaction equation

HRID 848208 reaction equation
[C:1]12[C:7](=[CH:8][CH:9]=[CH:10][CH:11]=1)[NH:6][C:5](=O)[O:4][C:2]2=O.CO[C:15]1[C:16]([NH2:21])=C[CH:18]=[CH:19][CH:20]=1.C1(C)C(S(O)(=O)=O)=CC=CC=1>C1(C)C(C)=CC=CC=1>[NH2:6][C:7]1[CH:8]=[CH:9][CH:10]=[CH:11][C:1]=1[C:2]1[O:4][C:5]2[CH:18]=[CH:19][CH:20]=[CH:15][C:16]=2[N:21]=1

Participants

5

Reactant 3

HCID 69252-Methylbenzenesulfonic acidHCID 70002-MethoxyanilineHCID 8359Isatoic Anhydride

Product 1

HCID 4602658ortho-aminophenylbenzoxazoleYield 23%

Reagents, catalysts & solvents 1

HCID 7237O-XyleneSolvent

Procedure

Isatoic anhydride (0.2 m), o-anisidine (0.22 m), and xylene (200 ml) were placed in a 3-neck, 300 ml round bottom flask fitted with thermometer, condenser, and magnetic stirrer. The reaction mixture was heated to reflux and allowed to stir at reflux overnight. Gas evolution appeared to be vigorous. Added a Dean-Stark trap and attempted to collect water. No water was evident after eight hours. Reaction mixture was cooled and allowed to stand overnight. Toluenesulfonic acid (1.5 g) was added and reaction mixture heated to reflux. Water was azeotroped from the reaction mixture. The xylene was stripped from the reaction mixture under aspirator vacuum. The residue was leached with benzene (500 ml). The benzene extract was then washed with 2% caustic until no further color was extracted. The benzene solution was filtered and evaporated to dryness. The residue was dissolved in boiling ethanol and allowed to stand in the refrigerator. The reddish crystals were filtered out and dried. Obtained 10 grams (23% yield); m.pt.=104°-107° C. Structure was confirmed by infra red (IR) and nuclear magnetic resonance (NMR) analysis.

Workup

  1. customfitted with thermometer, condenser, and magnetic stirrer
  2. temperatureThe reaction mixture was heated
  3. temperatureto reflux
  4. temperatureat reflux overnight
  5. additionAdded a Dean-Stark trap
  6. customto collect water
  7. customReaction mixture
  8. temperaturewas cooled
  9. waitto stand overnight
  10. customreaction mixture
  11. temperatureheated to reflux
  12. customWater was azeotroped from the reaction mixture
  13. extractionThe benzene extract
  14. washwas then washed with 2% caustic until no further color
  15. extractionwas extracted
  16. filtrationThe benzene solution was filtered
  17. customevaporated to dryness
  18. dissolutionThe residue was dissolved
  19. filtrationThe reddish crystals were filtered out
  20. customdried
  21. customObtained 10 grams (23% yield)

Sources & evidence

ORD record
ord-b90645bc5dd14ce2bdbdbd2cb631fc14
Source dataset
uspto-grants-1981_10
Patent number
US04294965

Reaction notes

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