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.
Flavellagic acid, C14H6O9, is obtained in conjunction with ellagic acid when gallic acid is oxidised with potassium persulphate and strong sulphuric acid. By the employment of a dilute acid, flavellagic acid almost free from ellagic acid can be produced, and for this purpose the following process is recommended (A. G. Perkin, Chem. Soc. Trans., 1906, 89, 251): 20 grams of gallic acid are treated with 160 c.c. of 96 per cent, sulphuric acid, 66 c.c. of water added, and the hot solution thus obtained is cooled to 50°, and maintained at this temperature during the gradual addition of 40 grams of potassium persulphate. A. G. Perkin and F. M. Perkin (Chem. Soc. Trans., 1908, 93, 1194) have obtained the same compound by the electrolytic oxidation of gallic acid in the presence of sulphuric acid, and more recently Bleuler and Perkin (ibid., 1916, IO9> 53) have prepared it by heating gallic acid at 110-120° with arsenic and sulphuric acids.
Flavellagic acid crystallises from pyridine in small yellow prismatic needles which contain pyridine, and do not melt below 360°. With nitric acid containing nitrous acid and subsequent dilution, it gives the blood-red coloration (Griessmayer reaction), which is also produced by ellagic acid. Dilute alkalis dissolve it with a yellowishgreen coloration, and by distillation with zinc-dust fluorene is produced. Acetylflavellagic acid, C14HO9(C2H3O)5, colourless needles, melts at 317-319°, and benzoylflavellagic acid, C14HO9(C7H5O)5, prismatic needles, melts at 287-289°. Flavellagic acid. dyes mordanted woollen cloth shades somewhat resembling but stronger than those produced by ellagic acid.
| Chromium | Aluminium | Tin. | Iron. |
| Yellowish-olive. | Pale greenish-yellow. | Pale yellow. | Dark olive-brown. |
By the action of boiling 50 per cent, potassium hydroxide soluion, flavellagic acid gives hexahydroxydiphenylmethylolid [KUVA PUUTTUU] colourless needles (melting-point above 300°). This compound dissolves in solutions of the alkali hydroxides with an orange-yellow tint, and this, on dilution with water and exposure to air, develops a strong bluish-violet coloration. The acetyl derivative, C13H2O8(C2H3O)6, colourless prismatic needles, melts at 232-234°. Flavellagic acid is hydroxyellagic acid, and possesses the following constitution: [KUVA PUUTTUU] (cf. Herzig and Tscherne, Monatsh., 1908, 29, 281).
Flavellagic acid gives with diazomethane the methyl ether C14HO4(OMe)5, melting-point 245°; and this is converted by methyl iodide and potassium hydroxide into methyl-3:4:5:6:2':3':4-heptamethoxydiphenyl-2:6'-dicarboxylate C12H(OMe)7(CO2Me)2, melting-point 83-87°. The latter, on hydrolysis with potassium hydroxide, yields the acid C12H(OMe)7(CO2H)2, melting-point 163-167°, in the anhydrous condition. From water it crystallises with iH2O and then melts at 95-100° (decomp.), (M. von Bronneck, Monatsh., 1908, 29, 281).
When gallic acid 3:4-dimethylether, or gallic acid trimethylether is oxidised by means of potassium persulphate and sulphuric acid at 45 (Herzig and Schmidinger, Monatsh., 1910, 31, 918), flavellagic acid tetramethyletheryellow needles, melting-point 270-271°, is produced, the acetyl derivative of which melts at 270-271°. By means of methyl sulphate and potassium hydroxide, the heptamethoxy compound (described above) is obtained.
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