Title:  Rhamnetin
CAS Registry Number:  90-19-7
CAS Name:  2-(3,4-Dihydroxyphenyl)-3,5-dihydroxy-7-methoxy-4
H-1-benzopyran-4-one
Synonyms:  3,3¢,4¢,5-tetrahydroxy-7-methoxyflavone;  7-methylquercetin;  b-rhamnocitrin;  cyanidenolon-7-methyl ether 1537
Molecular Formula:  C16H12O7
Molecular Weight:  316.26
Percent Composition:  C 60.76%, H 3.82%, O 35.41%
Literature References:  The aglucon of xanthorhamnin.  From fruit of 
Rhamnus cathartica L., 
Rhamnaceae:  Krassowski, 
J. Russ. Phys. Chem. Soc. 40, 1510 (1909); from commercial xanthorhamnin:  Nystrom 
et al., J. Org. Chem. 22, 1272 (1957).  Structure:  Oesch, Perkin, 
J. Chem. Soc. 105, 2354 (1914); Jurd, Horowitz, 
J. Org. Chem. 22, 1618 (1957).  Synthesis:  Kuhn, Low, 
Ber. 77, 211 (1944); Jurd, 
J. Am. Chem. Soc. 80, 5531 (1958); 
US 2892845 (1959 to USDA); Anand 
et al., J. Sci. Ind. Res. 21B, 322 (1962), 
C.A. 57, 13712f (1962); Kawano 
et al., Chem. Pharm. Bull. 15, 711 (1967).
Properties:  Yellow needles from acetone + methanol, mp 292-294°.  uv max (ethanol):  371, 256 nm (log e 4.41, 4.40).  Sol in hot phenol.  Slightly sol in hot water, hot alcohol, hot glacial acetic acid, hot acetone.  Freely sol in dil alkalies with intense yellow color.
Melting point:  mp 292-294°
Absorption maximum:  uv max (ethanol):  371, 256 nm (log e 4.41, 4.40)
 
Derivative Type:  Tetraacetate 
Molecular Formula:  C24H20O11
Molecular Weight:  484.41
Percent Composition:  C 59.51%, H 4.16%, O 36.33%
Properties:  Needles from acetone + methanol, mp 189-190°.
Melting point:  mp 189-190°
 
Use:  Has been used for dyeing wool and cotton.