Sodium Hydroxide → 2-Amino-6-(trifluoromethoxy)-5-benzothiazolol

HRID 482272Notes

Reaction equation

HRID 482272 reaction equation
[NH2:1][C:2]1[S:3][C:4]2[CH:10]=[C:9]([O:11][C:12]([F:15])([F:14])[F:13])[C:8]([O:16]C)=[CH:7][C:5]=2[N:6]=1.[OH-].[Na+]>Br>[NH2:1][C:2]1[S:3][C:4]2[CH:10]=[C:9]([O:11][C:12]([F:15])([F:13])[F:14])[C:8]([OH:16])=[CH:7][C:5]=2[N:6]=1

Participants

4

Reactant 2

HCID 14798Sodium HydroxideHCID 19063892HCID 19063892, compound

Product 1

HCID 190638932-Amino-6-(trifluoromethoxy)-5-benzothiazololYield 69.9%

Reagents, catalysts & solvents 1

HCID 260Hydrogen BromideSolvent

Conditions

Temperature
20 °C

Procedure

0.74 g of 2-amino-5-methoxy-6-(trifluoromethoxy)benzothiazole, in solution in 20 ml of 47% hydrobromic acid, are brought to reflux for 20 hours. After cooling to a temperature in the region of 20° C., the reaction mixture is poured in 20 ml of ice-cold water and the solution is basified using concentrated sodium hydroxide. The organic phase is then extracted with ethyl acetate, dried over magnesium sulphate, filtered and concentrated to dryness under reduced pressure (15 mm Hg, 2 kPa). The crude product thus obtained is purified by flash chromatography on a silica column, a dichloromethane/methanol (98/2 by volume) mixture being used as eluent. 0.49 g of 2-amino-5-hydroxy-6-(trifluoromethoxy)benzothiazole are thus isolated in the form of a white powder melting at 216° C. [(Analysis % calculated C: 38.40, H: 2.01, F: 22.78, N: 11.20, S: 12.82; % found C: 38.3, H: 1.9, F: 22.9, N: 11.2, S: 13.0); 1H N.M.R. spectrum (250 MHz, d6-(CD3)2SO, δ in ppm): 6.96 (broad s, 1H, aromatic H ortho to the OH), 7.54 (broad s, 2H, NH2), 7.61 (broad s, 1H, aromatic H meta to the OH), 9.95 (unresolved peak, 1H, OH)].

Workup

  1. temperatureto reflux for 20 hours
  2. extractionThe organic phase is then extracted with ethyl acetate
  3. dry with materialdried over magnesium sulphate
  4. filtrationfiltered
  5. concentrationconcentrated to dryness under reduced pressure (15 mm Hg, 2 kPa)
  6. customThe crude product thus obtained
  7. customis purified by flash chromatography on a silica column

Sources & evidence

ORD record
ord-5584a96ff730463d9505f0647d2e95ef
Source dataset
uspto-grants-1998_08
Patent number
US05795903

Reaction notes

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