Cyanogen Bromide → 2-amino-6-nitrobenzoxazole

HRID 2102802Notes

Reaction equation

HRID 2102802 reaction equation
[N:1]#[C:2]Br.[O-]Cl.[Na+].[NH2:7][C:8]1[CH:13]=[CH:12][C:11]([N+:14]([O-:16])=[O:15])=[CH:10][C:9]=1[OH:17].[OH-].[Na+]>O1CCCC1.O>[NH2:1][C:2]1[O:17][C:9]2[CH:10]=[C:11]([N+:14]([O-:16])=[O:15])[CH:12]=[CH:13][C:8]=2[N:7]=1

Participants

7

Reactant 4

HCID 10476Cyanogen Bromide2×HCID 14798Sodium HydroxideHCID 49847212-Amino-5-NitrophenolHCID 23665760Sodium Hypochlorite

Product 1

HCID 122515542-amino-6-nitrobenzoxazoleYield 71%

Reagents, catalysts & solvents 2

HCID 962WaterSolvent2×HCID 8028TetrahydrofuranSolvent2×

Procedure

A solution of cyanogen bromide (3.50 g, 33 mmol; caution: highly toxic! Waste disposal: addition of excess NaOCl to a basic aqueous solution of cyanogen bromide) in tetrahydrofuran (3 mL) was added to a solution of 2-amino-5-nitrophenol (4.62 g, 30 mmol) in tetrahydrofuran (20 mL). After stirring for 1 day at r.t, a precipitate had formed which was dissolved by addition of water (5 mL). After stirring further 3 days at r.t., water (10 mL) was added and NaOH was added until the mixture turned basic. The tetrahydrofuran was removed in vacuo and the precipitate formed in the remaining aqueous phase was separated by filtration, washed with water and recrystallized from methanol (100 mL). Upon additional fractional crystallisation of the mother liquor, a total of 3.80 g (21.2 mmol, 71%) of 2-amino-6-nitrobenzoxazole was obtained as a brown solid. LC/ESI-MS: m/z=180 [M+H]+; m/z=178 [M]−H−; R=2.52 min.

Workup

  1. customa precipitate had formed which
  2. stirringAfter stirring further 3 days at r.t.
  3. customThe tetrahydrofuran was removed in vacuo
  4. customthe precipitate formed in the remaining aqueous phase
  5. customwas separated by filtration
  6. washwashed with water
  7. customrecrystallized from methanol (100 mL)
  8. customUpon additional fractional crystallisation of the mother liquor

Sources & evidence

ORD record
ord-1ff1c8fe5f34425c81008a9497626d81
Source dataset
uspto-grants-2009_08
Patent number
US07576090B2

Reaction notes

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