1635. Caffeic Acid
Nomenclature
CAS number: 331-39-5
3-(3,4-Dihydroxyphenyl)-2-propenoic acid; 3,4-dihydroxycinnamic acid. C9H8O4; mol wt 180.16.
C 60.00%, H 4.48%, O 35.52%.
Description and references
Constituent of plants, probably occurs in plants only in conjugated forms, e.g., chlorogenic acid. Isoln from green coffee: Wolfrom et al., J. Agric. Food Chem. 8, 58 (1960); from roasted coffee: Krasemann, Arch. Pharm. 293, 721 (1960). Formation by acid hydrolysis of chlorogenic acid: Fiedler, Arzneim.-Forsch. 4, 41 (1954); Whiting, Carr, Nature 180, 1479 (1957); Guern, C.A. 61, 9965h (1964). Synthesis: Hayduck, Ber. 36, 2935 (1903); Posner, J. Prakt. Chem. 82, 432 (1910); Mauthner, ibid. 142, 33 (1935); Pandya et al., Proc. Indian Acad. Sci. 9A, 511 (1939); Neish, Can. J. Biochem. Physiol. 37, 1431 (1959). Review: Herrmann, Pharmazie 11, 433 (1956).
Properties
Yellow crystals from concd aq solns. Monohydrate from dil solns. Dec 223-225° (softens at 194°). Rf values: Fiedler, loc. cit. Sparingly sol in cold water. Freely sol in hot water, cold alc. Alkaline solns turn from yellow to orange.Derivative
Methyl ester.C10H10O4; mol wt 194.18.
C 61.85%, H 5.19%, O 32.96%.