The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918
Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.
This tannin group, which has for its mother substance diphenylmethylolid (2), is at present only represented by one well-authenticated member known as ellagitannin, unless indeed pomegranate tannin (see below) is a distinct compound. Whereas Perkin and Nierenstein (Chem. Soc. Trans., 1905, 87, 1428) considered that ellagitannin was probably formed by the condensation of two molecules of digallic acid and possessed the formula (1) or was a glucoside of this substance, according to Nierenstein, ellagitannin (q.v.) (cf. also Ber., 1912, 45, 365) is a glucoside of luteoic acid (3).
Numerous natural tannin matters yield ellagic acid, but these have been little investigated, and it is likely that glucosides giving ellagic acid by hydrolysis but differing from ellagitannin itself in the character ot their sugar nuclei will be later discovered.
Though various hydroxydiphenylmethylolid compounds have been synthetically prepared, e.g. metellagic acid, C15H5O4(OH), catellagic acid, C14H4O4(OH)2, flavellagic acid, C14HO4(OH)5, and coeruleoellagic (cyanellagic) acid, C14O4(OH)6, (loc. cit.), ellagic acid is the only member of this group which has been isolated from natural sources.
Pomegranate tannin, C20H16O13, is an amorphous greenish-yellow substance contained in the root bark of Punica granatum (Linn.). Boiling dilute sulphuric acid hydrolyses it with formation of a sugar and ellagic acid (Rembold, Annalen, 143, 385).
Ei kommentteja :
Lähetä kommentti