Organic Syntheses, CV 4, 711
Submitted by Charles E. Braun, Clinton D. Cook, Charles Merritt, Jr., and Joseph E. Rousseau
1.
Checked by William S. Johnson, George N. Sausen, and Paul R. Shafer.
1. Procedure
Twenty grams (0.112 mole) of finely powdered anthracene (Note
1) is suspended in
80 ml. of glacial acetic acid (Note
2) in a
500-ml. three-necked round-bottomed flask fitted with a
150-ml. dropping funnel, a
thermometer, and an
efficient motor-driven stirrer. The flask is immersed in a
water bath at 20–25°, and
8 ml. (0.126 mole) of concentrated nitric acid (70% by weight, sp. gr. 1.42), essentially free of
oxides of nitrogen, is added slowly from the dropping funnel with vigorous stirring. The rate of addition is controlled so that the reaction temperature does not exceed 30°. About 15–20 minutes is required for this step.
After all the
nitric acid has been added, the mixture is stirred until a clear solution is obtained (about 30 minutes), and stirring is then continued for an additional 30 minutes. The solution is filtered to remove any
anthracene, and a mixture of
50 ml. (0.60 mole) of concentrated hydrochloric acid (37% by weight, sp. gr. 1.19) and
50 ml. of glacial acetic acid is added slowly to the filtrate with vigorous stirring. The pale-yellow precipitate of
9-nitro-10-chloro-9,10-dihydroanthracene which forms is separated by suction filtration on a
sintered-glass funnel and is washed with two
25-ml. portions of glacial acetic acid and then with water until the washings are neutral. The product is removed from the funnel and triturated thoroughly with
60 ml. of warm (60–70°) 10% sodium hydroxide solution (Note
3). The crude orange
nitroanthracene is separated from the warm slurry by suction filtration and is treated with four
40-ml. portions of 10% sodium hydroxide solution (Note
3). The product is finally washed thoroughly with warm water until the washings are neutral to litmus. This treatment requires about 1.5–2 l. of water. The crude
9-nitroanthracene is air-dried and recrystallized from glacial
acetic acid (Note
2) and (Note
4). The yield of bright orange-yellow needles is
15–17 g. (
60–68%), m.p.
145–146°.
2. Notes
1.
Anthracene of good quality is required. The
Eastman Kodak Company product, m.p. 215–217°, is satisfactory, or practical grade anthracene may be purified by codistillation with
ethylene glycol.
2
3. The checkers found it desirable to carry out the trituration by grinding the mixture in a
mortar, because the nitrochloride has a tendency to form small, hard granules which otherwise may not come in contact with the alkali. The later treatments with alkali may be carried out satisfactorily in a
beaker, or directly on the funnel, if thorough mixing is obtained. It is desirable to remove as much of the mother liquor as possible by suction from each of the alkali treatments.
4. For recrystallization,
10 ml. of glacial acetic acid is used for each gram of dried product. It is important that the dissolution be carried out rapidly; otherwise some decomposition may occur, producing
anthraquinone as a contaminant. A satisfactory technique is to add the crude, dried, and crushed product rapidly in small portions to the total amount of boiling
acetic acid. The solution should then be filtered through a
steam-heated funnel.
3. Discussion
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