Title: Emodin
CAS Registry Number: 518-82-1
CAS Name: 1,3,8-Trihydroxy-6-methyl-9,10-anthracenedione
Additional Names: 1,3,8-trihydroxy-6-methylanthraquinone; 4,5,7-trihydroxy-2-methylanthraquinone; frangula emodin; rheum emodin; archin; frangulic acid
Molecular Formula: C15H10O5
Molecular Weight: 270.24
Percent Composition: C 66.67%, H 3.73%, O 29.60%
Literature References: Occurs mostly as the rhamnoside (see Frangulin) in rhubarb root, in alder buckthorn (Rhamnus frangula L.), in Cascara sagrada (Rhamnus purshiana DC., Rhamnaceae), also in Rumex and in other Polygonaceae. Isoln from rhubarb root: Tutin, Clewer, J. Chem. Soc. 99, 946 (1911); Carelli, Giuliano, Farmaco Ed. Prat. 12, 184 (1957); from bark of alder buckthorn: Bridel, Charaux, Bull. Soc. Chim. Biol. 15, 648 (1933). Identity with archin: Chaudhry et al., J. Sci. Ind. Res. 9B, No. 6, 142 (1950), C.A. 44, 9396h (1950). Synthesis from 3,5-dinitrophthalic anhydride and m-cresol: Elder, Widmer, Helv. Chim. Acta 6, 966 (1923); from 2-methylanthraquinone: Ayyangar et al., J. Sci. Ind. Res. 20B, 493 (1961), C.A. 57, 8514b (1962).
Properties: Orange needles from alc or by sublimation at 12 mm. mp 256-257°. Absorption max (ethanol): 222, 252, 265, 289, 437 nm (log e 4.55, 4.26, 4.27, 4.34, 4.10). Practically insol in water; sol in alc, aq alkali hydroxide solns (cherry-red color), Na2CO3 and NH3 solns. Soly at 25° (g/100 ml of satd soln): ether 0.140; chloroform 0.071; carbon tetrachloride 0.010; carbon bisulfide 0.009; benzene 0.041.
Melting point: mp 256-257°
Absorption maximum: Absorption max (ethanol): 222, 252, 265, 289, 437 nm (log e 4.55, 4.26, 4.27, 4.34, 4.10)
Derivative Type: 3-Methyl ether
Additional Names: 1,8-Dihydroxy-3-methoxy-6-methylanthraquinone; rheochrysidin
Molecular Formula: C16H12O5
Molecular Weight: 284.26
Percent Composition: C 67.60%, H 4.26%, O 28.14%
Properties: Brick-red, monoclinic needles, mp 207°. Occurs naturally as physcione or parietin.
Melting point: mp 207°
Derivative Type: Trimethyl ether
Molecular Formula: C18H16O5
Molecular Weight: 312.32
Percent Composition: C 69.22%, H 5.16%, O 25.61%
Properties: Pale yellow needles, mp 225°.
Melting point: mp 225°
NOTE: See also Aloe emodin.
Therap-Cat: Cathartic.
Keywords: Laxative/Cathartic.
Emorfazone EMPA Emtricitabine Enalapril Enalaprilat

Skeletal formula
Ball-and-stick model
CAS number 518-82-1 YesY
PubChem 3220
ChemSpider 3107 YesY
DrugBank DB07715
KEGG C10343 YesY
ChEBI CHEBI:42223 YesY
Jmol-3D images Image 1
Molecular formula C15H10O5
Molar mass 270.24 g mol−1
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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

Emodin (from Rheum emodi, a Himalayan rhubarb) is a purgative resin, 6-methyl-1,3,8-trihydroxyanthraquinone, from rhubarb, buckthorn and Japanese knotweed (Fallopia japonica syn. Polygonum cuspidatum).[1] It can also be isomers in botanical extracts.