Reaktion #94188

Reaktionsgleichung

water

N-methyl-N'-cyclohexylurea

malonic acid

acetic anhydride

→

1-methyl-3-cyclohexylbarbituric acid

Ausbeute 96.1%

Lösungsmittel

methanol

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturunder heating
2. 2
   TemperaturThe mixture is further heated at 80°-90° C. for 2 hours
3. 3
   Einengenconcentrated to dryness
4. 4
   SonstigeBy the above procedure is obtained a pale-yellow oil
5. 5
   Sonstigeseparate out
6. 6
   FiltrationThese crystals are collected by filtration
7. 7
   Waschenwashed with ethanol

Vorschrift

In 15 ml of acetic acid is dissolved 5 g of N-methyl-N'-cyclohexylurea together with 5 g of malonic acid under heating. Then, at 70° C., 15 ml of acetic anhydride is added dropwise over a period of 30 minutes. The mixture is further heated at 80°-90° C. for 2 hours, after which time 5 ml of water is added. The mixture is heated at 70° C. for 30 minutes and, then, concentrated to dryness. By the above procedure is obtained a pale-yellow oil. This oil is dissolved in methanol and allowed to stand in a refrigerator, whereupon needles separate out. These crystals are collected by filtration and washed with ethanol. The above procedure provided 6.9 g of 1-methyl-3-cyclohexylbarbituric acid as colorless crystals, melting point: 81°-82° C.

Quelle