Sulfuric Acid → HCID 178493795, compound

HRID 66750Notes

Reaction equation

HRID 66750 reaction equation
N[C:2]1[C:7]([O:8][CH3:9])=[N:6][C:5]([O:10][CH3:11])=[CH:4][N:3]=1.S(=O)(=O)(O)[OH:13].N([O-])=O.[Na+].NC(N)=O>O>[OH:13][C:2]1[C:7]([O:8][CH3:9])=[N:6][C:5]([O:10][CH3:11])=[CH:4][N:3]=1

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 1176UreaHCID 205289233,5-Dimethoxypyrazin-2-amineHCID 23668193Sodium Nitrite

Product 1

HCID 178493795HCID 178493795, compound

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
60 °C

Procedure

A solution of 2-amino-3,5-dimethoxypyrazine (0.02 mole) in 300 ml. of 6 M sulfuric acid at 0°-5° C. is treated with 0.022 mole sodium nitrite in 25 ml. of water at such a rate to insure that the temperature of the reaction mixture does not rise above 5° C. After standing 45 minutes at 0°-5° C., a little urea is added to destroy excess nitrous acid and the mixture then is treated with sodium hydroxide solution until strongly basic. The reaction mixture is warmed to 60° C. for one hour and then brought to pH 8.5. The mixture is concentrated to a third of the original volume and cooled in the refrigerator overnight. The product is separated by filtration and dried in vacuo, recrystallized from a suitable solvent to give 2-hydroxy-3,5-dimethoxypyrazine.

Workup

  1. customdoes not rise above 5° C
  2. customto destroy excess nitrous acid
  3. additionthe mixture then is treated with sodium hydroxide solution until strongly basic
  4. concentrationThe mixture is concentrated to a third of the original volume
  5. temperaturecooled in the refrigerator overnight
  6. customThe product is separated by filtration
  7. customdried in vacuo
  8. customrecrystallized from a suitable solvent

Sources & evidence

ORD record
ord-22a4062c69c940d6a699728656bd9c55
Source dataset
uspto-grants-1982_08
Patent number
US04343802

Reaction notes

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