Flavogallol.(CHAPTER XII. Diphenyl-Dimethylolid Group.)(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.

When gallic acid in sulphuric acid solution is treated with arsenic acid and the mixture heated at 110-120° for six hours, a mixture containing flavellagic and coeruleoellagic acids is mainly produced, though when the oxidation is carried out in the presence of 80 per cent, sulphuric acid flavogallol, C₂₁H₈O₁₂, is obtained. This consists of hair-like yellow needles, sparingly soluble in the usual solvents, soluble in sodium hydroxide solution with an orangeyellow colour. With sulphuric acid it yields the anhydrosulphate C₂₁H₆O₁₁.H₂SO₄, orange-yellow prisms, whereas the tripotassium salt, C₂₁H₅O₁₂K₃, prepared with alcoholic potassium acetate forms an orange-coloured crystalline powder.

Acetylflavogallol, C₂₁H₂O₁₂(C₂H₃O)₆, small prismatic needles, melts and decomposes at 278-280°, and the corresponding benzoyl compound, C₂₁H₂O₁₂(C₇H₅O)₆, yellow prisms, at 326-328°. With boiling aniline flavogallol yields the anilide C₂₁H₇O₁₁.NH.C₆H₅, which crystallises in yellow needles, melting above 345°. In the paste form flavogallol readily dyes mordanted fabrics, and employing woollen cloth the following shades are produced:

Chromium.	Copper.	Tin.	Iron.
Dull olive-yellow.	Pale brown.	Pale orange-yellow.	Brownish black.

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