Org. Synth. 1945, 25, 78
DOI: 10.15227/orgsyn.025.0078
2-NITRO-4-METHOXYANILINE
[p-Anisidine, 2-nitro-]
Submitted by Paul E. Fanta and D. S. Tarbell.
Checked by W. E. Bachmann and N. C. Deno.
1. Procedure
A. 2-Nitro-4-methoxyacetanilide. In a 2-l. three-necked, round-bottomed flask equipped with a mechanical stirrer and a thermometer are placed 123 g. (1 mole) of p-anisidine (Note 1), 300 ml. of glacial acetic acid, and 217 ml. of water. Stirring is started, and, when the p-anisidine has dissolved, 350 g. of ice is added. When the temperature reaches 0–5°, 103 ml. (1.1 moles) of acetic anhydride is added all at once with rapid stirring. Within several seconds the contents of the flask set to a crystalline mass and the temperature rises to 20–25°. The flask is heated on a steam bath until the crystalline material dissolves and is then cooled with stirring to 45°, at which temperature crystals begin to separate. An ice bath is applied, and 100 ml. (55% excess) of concentrated nitric acid (sp. gr. 1.42) is added all at once. The temperature rises rapidly to 70° and soon begins to fall. By suitable adjustment of the cooling bath the temperature is maintained at 60–65° for 10 minutes and then brought down to 25° in the course of 10 minutes (Note 2).
The solution is chilled overnight in an ice chest, and the precipitated yellow crystals are collected on a 19-cm. Büchner funnel. The crystals are washed with 270 ml. of ice-cold water and pressed as dry as possible with a rubber dam. The filter cake can be dried (Note 3) in air or in a vacuum desiccator over calcium chloride and soda lime. The yield of 2-nitro-4-methoxyacetanilide melting at 116–116.5° is 158–168 g. (75–79%).
B. 2-Nitro-4-methoxyaniline. A mixture of 160 g. of 2-nitro-4-methoxyacetanilide and 250 ml. of cold Claisen's alkali (Note 4) in a 2-l. beaker is stirred and warmed on a steam bath for 15 minutes; it first becomes liquid and then sets to a thick, red paste. After the addition of 250 ml. of hot water the mixture is stirred and digested on a steam bath for an additional 15 minutes and then cooled to 0–5°. The product is collected on a 19-cm. Büchner funnel, washed with three 160-ml. portions of ice-cold water, and pressed as dry as possible with a rubber dam. The yield of vacuum-dried product melting at 122.5–123° is 122–124 g. (95–97%).
2. Notes
1.
Eastman Kodak Company's Practical grade of p-anisidine was used.
2.
In a run in which the mixture was allowed to cool spontaneously from 65° the product became dark.
3.
Drying is unnecessary if the
2-nitro-4-methoxyacetanilide is used in step B. The material may be recrystallized with
97% recovery from dilute aqueous
ethanol (2 ml. of 95% ethanol and 4 ml. of water per gram). The product so obtained melts at
116.5–117°.
4.
Claisen's alkali is prepared by dissolving
88 g. of potassium hydroxide in 63 ml. of water, cooling, and diluting to 250 ml. with
methanol.
3. Discussion
2-Nitro-4-methoxyacetanilide has been prepared by the nitration of
p-acetaniside.
1 2 3 4 The procedure described for the nitration is essentially that used by Lothrop.
4
2-Nitro-4-methoxyaniline has been prepared by heating
nitrohydroquinone dimethyl ether with aqueous
ammonia;
5 by heating the
tetramethylammonium salt of 3-nitro-4-aminophenol;
6 by the hydrolysis of
2-nitro-4-methoxyacetanilide1 with alcoholic
potassium hydroxide2,3 or
hydrochloric acid;
4 and by the hydrolysis of the
p-toluenesulfonamide,
7 the
3-nitrobenzenesulfonamide,
8 the
3-nitro-p-toluenesulfonamide,
8 the
benzenesulfonamide,
9 and the
acetyl derivative of the p-toluenesulfonamide10 of
2-nitro-4-methoxyaniline with concentrated
sulfuric acid.
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
soda lime
Nitro-4-methoxyacetanilide
2-Nitro-4-methoxyacetanilide
acetyl derivative of the p-toluenesulfonamide
ethanol (64-17-5)
calcium chloride (10043-52-4)
sulfuric acid (7664-93-9)
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
ammonia (7664-41-7)
methanol (67-56-1)
acetic anhydride (108-24-7)
nitric acid (7697-37-2)
potassium hydroxide (1310-58-3)
2-Nitro-4-methoxyaniline,
p-Anisidine, 2-nitro- (96-96-8)
Benzenesulfonamide (98-10-2)
nitrohydroquinone dimethyl ether (89-39-4)
3-nitrobenzenesulfonamide (121-52-8)
p-anisidine (104-94-9)
p-toluenesulfonamide (70-55-3)
p-acetaniside (51-66-1)
3-nitro-p-toluenesulfonamide
tetramethylammonium salt of 3-nitro-4-aminophenol
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