Malonic Acid → Dimethylbarbituric acid

HRID 648887Notes

Reaction equation

HRID 648887 reaction equation
[CH3:1][NH:2][C:3]([NH:5][CH3:6])=[O:4].[C:7]([OH:13])(=O)[CH2:8][C:9]([OH:11])=O.C(OC(=O)C)(=O)C>C(O)(=O)C>[CH3:1][N:2]1[C:7](=[O:13])[CH2:8][C:9](=[O:11])[N:5]([CH3:6])[C:3]1=[O:4]

Participants

5

Reactant 3

HCID 867Malonic AcidHCID 7293N,N'-DimethylureaHCID 7918Acetic Anhydride

Product 1

HCID 69860Dimethylbarbituric acidYield 73.4%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

In 600 ml of glacial acetic acid were dissolved 276 g (3.14 mol) of 1,3-dimethylurea and 376 g (3.62 mol) of malonic acid at 60° to 70° C. Then, 1,250 ml of acetic anhydride was added thereto, and the temperature was gradually elevated up to 90° C. After stirring for 6 hours, the mixture was left to stand at room temperature overnight. The glacial acetic acid and acetic anhydride were removed by distillation under reduced pressure, and the residue, while hot, was poured into 500 ml of ethanol. The thus precipitated crystals were collected by filtration and heatrefluxed in 380 ml of concentrated hydrochloric acid and 400 ml of water for 2 hours, and then ice-cooled for 6 hours. The precipitated crystals were separated by filtration and washed with a small amount of ethanol to obtain 360 g of 1,3-dimethylbarbituric acid.

Workup

  1. customwas gradually elevated up to 90° C
  2. waitthe mixture was left
  3. waitto stand at room temperature overnight
  4. customThe glacial acetic acid and acetic anhydride were removed by distillation under reduced pressure
  5. additionthe residue, while hot, was poured into 500 ml of ethanol
  6. filtrationThe thus precipitated crystals were collected by filtration
  7. wait400 ml of water for 2 hours
  8. temperatureice-cooled for 6 hours
  9. customThe precipitated crystals were separated by filtration
  10. washwashed with a small amount of ethanol

Sources & evidence

ORD record
ord-856c349cad624afc8ec66fd2ce621f59
Source dataset
uspto-grants-1988_04
Patent number
US04737442

Reaction notes

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