Bromhydrol → 5-Bromophthalazine

HRID 2075352Notes

Reaction equation

HRID 2075352 reaction equation
BrC1C=C(C=CC=1)/[CH:5]=[N:6]/[N:7]=[CH:8]/[C:9]1[CH:14]=[CH:13][CH:12]=[C:11]([Br:15])[CH:10]=1.[Cl-].[Al+3].[Cl-].[Cl-].[Br-].[Al+3].[Br-].[Br-]>O>[Br:15][C:11]1[CH:12]=[CH:13][CH:14]=[C:9]2[C:10]=1[CH:5]=[N:6][N:7]=[CH:8]2

Participants

5

Reactant 3

HCID 166749BromhydrolHCID 6451240Aluminum(III) ChlorideHCID 12755061(E)-1-(3-bromophenyl)-N-[(E)-(3-bromophenyl)methylideneamino]methanimine

Product 1

HCID 136493705-BromophthalazineYield 42%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
192.5 °C

Procedure

To a 250 mL 3-neck round-bottom flask was added (1E,2E)-1,2-bis(3-bromobenzylidene)hydrazine (13.0 g, 35.5 mmol), aluminum(III) chloride (71.0 g, 533 mmol), and aluminum(III) bromide (71.0 g, 266 mmol). The mixture was stirred at 185-200° C. for 1 hour. The dark gum was cooled in an ice bath and slowly treated with 1.5 L of water. The suspension was filtered, and the precipitate was washed with 5% HCl. The solution was made basic with 15% potassium hydroxide and extracted with EtOAc three times. The organic extracts were dried over sodium sulfate, filtered and concentrated in vacuo. The residue was recrystallized from EtOAc and hexane to provide 5-bromophthalazine (3.12 g, 42%). LCMS (M+H) 209.2 calc. for C8H6BrN2 209.0. 1H NMR (400 MHz, CDCl3): δ ppm 7.78-7.83 (m, 1H) 7.95 (d, J=8.02 Hz, 1H) 8.14 (d, 1H) 9.49 (s, 2H).

Workup

  1. temperatureThe dark gum was cooled in an ice bath
  2. filtrationThe suspension was filtered
  3. washthe precipitate was washed with 5% HCl
  4. extractionextracted with EtOAc three times
  5. dry with materialThe organic extracts were dried over sodium sulfate
  6. filtrationfiltered
  7. concentrationconcentrated in vacuo
  8. customThe residue was recrystallized from EtOAc and hexane

Sources & evidence

ORD record
ord-afe79da064dd4cb4b53d98a8bd6ca29f
Source dataset
uspto-grants-2011_04
Patent number
US07919504B2

Reaction notes

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