A
1-l. three-necked flask is fitted with a sealed Hershberg stirrer, a reflux condenser, and a dropping funnel. The flask is charged with
650 ml. of acetic anhydride, and
107 g. (107 ml., 1 mole) of o-toluidine (Note
1) is introduced from the dropping funnel. The mixture becomes very warm. After the amine has been completely added, the solution is cooled to 12–13° in an
ice-salt bath (Note
2). During the cooling, the dropping funnel and condenser are replaced by another dropping funnel containing
126 ml. (2 moles) of 70% nitric acid and a thermometer which can be read to within 0.5° in the range from 10° to 20° (Note
3).
The
nitric acid is added drop by drop to the cold slurry at a rate which maintains the temperature carefully within the limits of 10–12° (Note
4). If the temperature persists in dropping, the addition is stopped after about 5 minutes. The ice bath is removed until the temperature rises 0.5°, the ice-salt bath is replaced, and addition is continued. As the reaction progresses, the
acetotoluide which may have precipitated redissolves, and the solution becomes deeply colored. The addition is complete in 1–2 hours, and the nitro compounds may start to separate.
The solution is poured, with stirring, into 3 l. of ice water. The mixture of
4- and 6-nitroacetotoluides precipitates as a creamcolored solid which is collected on a
large Büchner funnel. After thorough washing with four 500-ml. portions of ice water, the precipitate is partly dried by suction (Note
5). The moist product is then placed in a
steam-distillation apparatus (Note
6), covered with
300 ml. of concentrated hydrochloric acid, and heated until the mixture boils. The acetotoluides are rapidly hydrolyzed, and the solution becomes dark red. Steam is then introduced, and the distillation is thus continued until 36 l. of distillate has been collected (Note
7) and (Note
8). The
2-amino-3-nitrotoluene, which separates as bright orange needles when the distillate is cooled, is collected on a
large Büchner funnel. The dried product amounts to
75–84 g. (
49–55%), m.p.
92–94°. The product may be further purified by a second steam distillation. Ten grams of the amine is distilled from 150 ml. of water, and 3 l. of distillate is collected, yielding
8.7 g. of
2-amino-3-nitrotoluene, m.p.
95–96° (cor.).