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Org. Synth. 1949, 29, 66
DOI: 10.15227/orgsyn.029.0066
1-METHYLAMINOANTHRAQUINONE
[Anthraquinone, 1-methylamino-]
Submitted by C. V. Wilson, J. B. Dickey, and C. F. H. Allen.
Checked by George L. Evans and R. S. Schreiber.
1. Procedure
A 1-gal. autoclave (p. 80) (Note 1) is charged with 399 g. (1.29 moles) of technical sodium anthraquinone-α-sulfonate (Note 2), 45 g. (0.43 mole) of sodium chlorate, 780 g. (6.25 moles) of a 25% aqueous solution of methylamine, and 1.2 l. of water. The mixture is heated, with stirring, for 12 hours at 130–135° (Note 3). The heat is then shut off, but stirring is continued so that the product separates in an easily removable form. When cold, the autoclave is opened and the contents are removed; the material adhering to the walls is removed by water. The solid is filtered on a 13-cm. Büchner funnel. The red product is washed with two 500-ml. portions of hot water (70°) and dried in the air. The yield of 1-methylaminoanthraquinone, melting at 166–171° (Note 4), is 180–199 g. (59–65%) (Note 5) and (Note 6).
2. Notes
1. A shaking autoclave employed for high-pressure hydrogenations may be used equally well, but the quantities taken must be reduced to 155 g. (0.5 mole) of sodium anthraquinone-α-sulfonate, 17.5 g. of sodium chlorate, 300 g. of a 25% aqueous methylamine solution, and 600 ml. of water. The checkers used a 2-gal. stirred autoclave (stainless steel).
2. A corresponding quantity of the potassium salt1 can be utilized.
3. According to the checkers the heating time may be decreased to 8 hours if desirable.
4. The melting point varies slightly with the method of heating; if the bath is preheated to 160° before the sample is inserted, the melting point is 168–169.5° When taken in the ordinary way, the melting point is 166–171°. This product is sufficiently pure for most purposes. One recrystallization from toluene raises the melting point 1°.
5. The yield depends upon the purity of the sodium anthraquinone-α-sulfonate. Apparent yields of as high as 87% have been obtained. The checkers employed technical-grade material, which apparently resulted in an appreciable decrease in the yields of 76–80% reported by the submitters.
6. α-Chloroanthraquinone2 can be used as a starting material. In this case, 433 g. (1.79 moles) is taken, together with 1.5 l. of pyridine, 600 ml. of 25% aqueous methylamine, and 2.5 g. of a copper salt. The product is washed with dilute (2%) hydrochloric acid. The yield is 380–400 g. (90–95%).
3. Discussion
1-Methylaminoanthraquinone has been prepared from 1-chloro-, 1-bromo-, and 1-nitroanthraquinone by treatment with alcoholic methylamine under pressure,3 from 1-methoxy- and 1-phenoxyanthraquinone with methylamine in pyridine solution at 150°;4 from potassium anthraquinone-1-sulfonate with aqueous methylamine at 150–160°;5,6 from 1-aminoanthraquinone by treatment with formaldehyde,7 or methanol8 in sulfuric acid or oleum; and by hydrolysis of p-toluenesulfonylmethylaminoanthraquinone with sulfuric acid.9
This preparation is referenced from:

References and Notes
  1. Org. Syntheses Coll. Vol. 2, 539 (1943).
  2. Org. Syntheses Coll. Vol. 2, 128 (1943).
  3. Ger. pat. 144,634 [Frdl., 7, 201 (1902–1904)].
  4. Ger. pat. 165,728 [Frdl., 8, 289 (1905–1907)].
  5. Ger. pat. 175,024 [Frdl., 8, 283 (1905–1907)].
  6. Ger. pat. 256,515 [Frdl., 11, 551 (1912–1914)].
  7. Ger. pat. 156,056 [Frdl., 8, 288 (1905–1907)].
  8. Ger. pat. 288,825 [Frdl., 12, 414 (1914–1916)].
  9. Ullmann and Fodor, Ann., 380, 320 (1911).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

copper salt

1-chloro-, 1-bromo-, and 1-nitroanthraquinone

1-methoxy- and 1-phenoxyanthraquinone

sulfuric acid or oleum

sulfuric acid (7664-93-9)

hydrochloric acid (7647-01-0)

methanol (67-56-1)

formaldehyde (50-00-0)

pyridine (110-86-1)

toluene (108-88-3)

sodium chlorate (7775-09-9)

methylamine (74-89-5)

α-Chloroanthraquinone (82-44-0)

potassium anthraquinone-1-sulfonate (30845-78-4)

1-aminoanthraquinone (82-45-1)

1-METHYLAMINOANTHRAQUINONE,
Anthraquinone, 1-methylamino- (82-38-2)

sodium anthraquinone-α-sulfonate (128-56-3)

p-toluenesulfonylmethylaminoanthraquinone