963. Barbituric Acid

Nomenclature

CAS number: 67-52-7
2,4,6(1H,3H,5H)-pyrimidinetrione; malonylurea; 2,4,6-trioxohexahydropyrimidine.
C4H4N2O3; mol wt 128.09.
C 37.51%, H 3.15%, N 21.87%, O 37.47%.

Description and references

Prepn from hydurilic acid + nitric acid: Baeyer, Ann. 127, 199 (1863); ibid. 130, 129 (1864). Structure: Mulder, Ber. 6, 1233 (1873). Prepd from ethyl malonate and urea using sodium ethoxide as a condensing agent: Dickey, Gray, Org. Synth. coll. vol. II, 60 (1943). Crystal structure: Bolton, Nature 201, 987 (1964). Toxicity study: E. I. Goldenthal, Toxicol. Appl. Pharmacol. 18, 185 (1971). Unsubstituted barbituric acid has no hypnotic properties. Review: Carter, J. Chem. Educ. 28, 524 (1951).

Chemical structure

Derivative

Dihydrate.

Properties

Rhombs from water. mp ≈248° when anhydrous, with some decompn. Strong acid. K at 25° = 9.9 × 105. uv spectrum: Hartley, J. Chem. Soc. 87, 1808 (1905). Difficultly sol in cold water; freely sol in hot water, in dil acids. Forms salts with metals. LD50 orally in male rats: >5000 mg/kg (Goldenthal).

Use

Manuf plastics, pharmaceuticals.