Title: Allobarbital
CAS Registry Number: 52-43-7
CAS Name: 5,5-Di-2-propenyl-2,4,6(1H,3H,5H)-pyrimidinetrione
Additional Names: 5,5-diallylbarbituric acid; allobarbitone
Molecular Formula: C10H12N2O3
Molecular Weight: 208.21
Percent Composition: C 57.69%, H 5.81%, N 13.45%, O 23.05%
Literature References: Prepn: US 1042265 (1912). Acute toxicity: F. Sandberg, Acta Physiol. Scand. 24, 7 (1951).
Properties: Crystals, leaflets. Slightly bitter taste, mp 171-173°. One part dissolves in about 300 parts water, 50 parts boiling water, 20 parts cold alcohol, 20 parts ether; very sol in hot alcohol and in acetone; sol in ethyl acetate. Insol in aliphatic hydrocarbons. A satd aq soln is acid to litmus. LD50 i.p. in rats: 127.3 mg/kg (Sandberg).
Melting point: mp 171-173°
Toxicity data: LD50 i.p. in rats: 127.3 mg/kg (Sandberg)
NOTE: This is a controlled substance (depressant): 21 CFR, 1308.13.
Therap-Cat: Sedative, hypnotic.
Keywords: Sedative/Hypnotic; Barbituric Acid Derivatives.
Allocholesterol Alloclamide Allocryptopine Allocupreide Sodium Allopregnan-20alpha-ol-3-one

Allobarbital ball-and-stick animation.gif
Systematic (IUPAC) name
Clinical data
Legal status Schedule IV (US)
CAS number 52-43-7
ATC code N05CA21
PubChem CID 5842
ChemSpider 5635 YesY
KEGG D02817 YesY
Synonyms 5,5-Diallylbarbituric acid, Allobarbital
Chemical data
Formula C10H12N2O3 
Mol. mass 208.214 g/mol
 YesY (what is this?)  (verify)

Allobarbital, also known as allobarbitone and branded as Cibalgine or Dial-Ciba (in combination with ethyl carbamate), is a barbiturate derivative invented in 1912 by Ernst Preiswerk and Ernst Grether working for CIBA. It was used primarily as an anticonvulsant[1] although it has now largely been replaced by newer drugs with improved safety profiles. Other uses for allobarbital included as an adjutant to boost the activity of analgesic drugs, and use in the treatment of insomnia and anxiety.

Allobarbital was never particularly widely used compared to better known barbiturates such as phenobarbital and secobarbital, although it saw more use in some European countries such as Bulgaria and Slovakia,[2] and is still used in for example Poland, but only as compound.[3]