Title: Juglone
CAS Registry Number: 481-39-0
CAS Name: 5-Hydroxy-1,4-naphthalenedione
Additional Names: 5-hydroxy-1,4-naphthoquinone; 8-hydroxy-1,4-naphthoquinone; C.I. 75500; C.I. Natural Brown 7; nucin; regianin
Molecular Formula: C10H6O3
Molecular Weight: 174.15
Percent Composition: C 68.97%, H 3.47%, O 27.56%
Literature References: Coloring matter occurring in various Juglandaceae spp: Brissemoret, Combes, Compt. Rend. 141, 838 (1905). Isoln from walnut shells: Combes, Bull. Soc. Chim. 1(4), 800 (1907). Isoln and description of sedative properties in fish, mammals: B. A. Westfall et al., Science 134, 1617 (1961). Isoln from pecans and identification as inhibitory agent of mycelial growth of Fusicladium effusum: P. A. Hedin et al., J. Agric. Food Chem. 28, 340 (1980). Synthesis: Bernthsen, Semper, Ber. 20, 938 (1887); Willstätter, Wheeler, Ber. 47, 2798 (1914); Teuber, Götz, Ber. 87, 1236 (1954); C. Grundmann, Synthesis 1977, 644. Tumor-promoting activity study: B. L. Van Duuren et al., J. Med. Chem. 21, 26 (1978). Use as pH indicator: S. S. Sawhney, B. M. L. Bhatia, J. Indian Chem. Soc. 57, 438 (1980).
Properties: Yellow needles from benzene + petr ether, mp 155°. Sublimes. Absorption max (methanol): 420 nm (log e 3.56). Volatile with steam. Slightly sol in hot water; freely sol in chloroform, benzene; sol in alcohol, ether; sol in aq solns of alkalies giving a purplish-red soln.
Melting point: mp 155°
Absorption maximum: Absorption max (methanol): 420 nm (log e 3.56)
Julocrotine Juniper Tar Justicidins Juvenile Hormones Kahalalide F

Skeletal formula
Ball-and-stick model
CAS number 481-39-0 YesY
PubChem 3806
ChemSpider 3674 N
RTECS number QJ5775000
Jmol-3D images Image 1
Molecular formula C10H6O3
Molar mass 174.15 g/mol
Appearance yellow solid
Solubility in water slightly sol.
R-phrases R25
S-phrases S28 S45
Related compounds
Related compounds quinone
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) or 5-hydroxynaphthoquinone, is an organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. Other names in industry are Nucin, Regianin, NCI 2323, and Oil Red BS.

Juglone occurs naturally in the leaves, roots, husks, fruit (the epicarp), and bark of plants in the Juglandaceae family, particularly the black walnut (Juglans nigra), and is toxic or growth-stunting to many types of plants. It is sometimes used as a herbicide, as a dye for cloth and inks, and as a coloring agent for foods and cosmetics.