Lecanoric acidCHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.(Osa artikkelista)

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.

Lecanoric acid (Diorsellinic acid), C₁₆H₁₄O₇, H₂O, was first described by Schunck under the name of "lecanorin,"and was isolated by him from various species of the Lecanora and Variolaria lichens. It is also present in some quantity in the Rocella canariensis, R. portentosa, R. sinensis, and Parmelia perlata (loc. cit.), and, according to Hesse (Annalen, 139, 24), is best isolated by the following method, which is a modification of that originally devised by Schunck. The finely divided lichen is extracted with ether, the extract evaporated, and the greenish-white crystalline residue treated with lime water. The solution, when neutralised with acid, gives a precipitate of lecanoric acid, which is collected and crystallised from alcohol. In case the product is not quite pure it is treated with ether, which dissolves the acid, but not the impurity.

Lecanoric acid crystallises in colourless needles, melting-point 166° (Hesse, Ber., 37, 4693), the solutions of which possess an acid reaction. With alcoholic ferric chloride it gives a dark purple coloration, and with dilute calcium hypochlorite a blood-red liquid, which, according to Hesse, is characteristic, and can be used to distinguish this substance from the known lichen acids.

[---]