Methylhydrazine → 5-(4-Bromophenyl)-1-methyl-1H-pyrazole

HRID 501499Notes

Reaction equation

HRID 501499 reaction equation
[CH3:1][C:2]([C:4]1[CH:9]=[CH:8][C:7]([Br:10])=[CH:6][CH:5]=1)=O.[CH3:11][NH:12][NH2:13].[CH3:14]N(C=O)C>>[Br:10][C:7]1[CH:8]=[CH:9][C:4]([C:2]2[N:13]([CH3:14])[N:12]=[CH:11][CH:1]=2)=[CH:5][CH:6]=1

Participants

4

Reactant 3

HCID 6061MethylhydrazineHCID 6228Dimethylformamide2×HCID 7466p-Bromoacetophenone

Product 1

HCID 125810925-(4-Bromophenyl)-1-methyl-1H-pyrazole

Procedure

A N,N′-dimethylformamide (15 mL) solution of 4-bromoacetophenone (10.60 g, 53.25 mmols) and N,N′-dimethylformamide dimethyl acetal (2.5 equivalents) was heated at 125 degrees Celcius for 3 hours. The dark red solution was cooled to room temperature. The volatiles were removed by rotary evaporation providing a red viscous oil. To this substance was added anhydrous N,N′-dimethylformamide (15 mL) and methyl hydrazine (7.6 g, 160 mmols, 3 equivalents). The mixture was stirred at room temperature for 1 hour and then heated at 75 degrees Celcius for 4 hours. The volatiles were removed by rotary evaporation and the crude residue was taken up in a small volume of methylene chloride. This red solution was applied to a cartridge of silica gel. The cartridge was eluted with a 20:80 mixture of ethyl acetate and hexanes, respectively. The appropriate fractions were combined and concentrated to produce 12.5 g of a white solid.

Workup

  1. customThe volatiles were removed by rotary evaporation
  2. customproviding a red viscous oil
  3. temperatureheated at 75 degrees Celcius for 4 hours
  4. customThe volatiles were removed by rotary evaporation
  5. washThe cartridge was eluted with a 20:80 mixture of ethyl acetate and hexanes
  6. concentrationconcentrated

Sources & evidence

ORD record
ord-2d2946fd2f7846dba154bc2fc5572a18
Source dataset
uspto-grants-2010_08
Patent number
US07772269B2

Reaction notes

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