4804. Hydroorotic Acid

Nomenclature

CAS number: 155-54-4
Hexahydro-2,6-dioxo-4-pyrimidinecarboxylic acid; 4,5-dihydroorotic acid.
C5H6N2O4; mol wt 158.11.
C 37.98%, H 3.82%, N 17.72%, O 40.48%.

Description and references

Prepn from carbethoxyasparagine: Miller et al., J. Am. Chem. Soc. 75, 6086 (1953); US 2773872 (1956 to Merck & Co.).

Chemical structure

Derivative

l-Form.

Properties

Crystals, dec 266°. [α]D25.3 +33.23° (c = 1.992 in 1% NaHCO3).

Derivative

d-Form.

Properties

Crystals from water, dec 266°. [α]D25.3 31.54° (c = 2.01 in 1% NaHCO3).

Derivative

dl-Form.

Properties

Crystals, dec 259°. Forms a water-sol salt.

Use

The l- and dl-dihydroorotic acids are precursors to the biological pyrimidines, such as thymine, uracil, cytosine and hydroxymethylcytosine. When employed in large amounts d-dihydroorotic acid is an antimetabolite of l-dihydroorotic acid in pyrimidine utilization. It has also been found to inhibit the orotic acid utilization of those organisms which have a requirement for it in order to grow. In general it may be said to inhibit bacterial growth.