Malonic Acid → Dimethylbarbituric acid

HRID 648884Notes

Reaction equation

HRID 648884 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. To the solution was added 1,250 ml of acetic anhydride, followed by elevating the temperature gradually up to 90° C. After stirring for 6 hours, the mixture was allowed to stand at room temperature overnight, and then the glacial acetic acid and acetic anhydride were removed by distillation under reduced pressure. The residue, while hot, was poured into 500 ml of ethanol, and the precipitated crystals were collected by filtration. The crystals were heat-refluxed in 380 ml of concentrated hydrochloric acid and 400 ml of water for 2 hours and then allowed to stand for 6 hours under ice-cooling. The precipitated crystals were collected by filtration and washed with a small amount of ethanol to obtain 360 g (73%) of 1,3-dimethylbarbituric acid having a melting point of 124° to 125° C.

Workup

  1. customgradually up to 90° C
  2. waitto stand at room temperature overnight
  3. customthe glacial acetic acid and acetic anhydride were removed by distillation under reduced pressure
  4. additionThe residue, while hot, was poured into 500 ml of ethanol
  5. filtrationthe precipitated crystals were collected by filtration
  6. temperatureThe crystals were heat-refluxed in 380 ml of concentrated hydrochloric acid
  7. wait400 ml of water for 2 hours
  8. waitto stand for 6 hours under ice-
  9. temperaturecooling
  10. filtrationThe precipitated crystals were collected by filtration
  11. washwashed with a small amount of ethanol

Sources & evidence

ORD record
ord-70e890e7b834497f9650967634d934b1
Source dataset
uspto-grants-1988_04
Patent number
US04737442

Reaction notes

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