Org. Synth. 1934, 14, 24
DOI: 10.15227/orgsyn.014.0024
DIAZOAMINOBENZENE
[Triazene, 1,3-diphenyl-]
Submitted by W. W. Hartman and J. B. Dickey.
Checked by C. R. Noller and C. R. Kemp.
1. Procedure
In a 5-l. flask fitted with a mechanical stirrer and a dropping funnel are placed 1 kg. of cracked ice, 1.5 l. of water, 279 g. (3 moles) of a technical grade of aniline, and 458 g. (388 cc., 4.5 moles) of concentrated hydrochloric acid (sp. gr. 1.18). The stirrer is started, and a solution of 109 g. (1.5 moles) of 95 per cent sodium nitrite in 250 cc. of water is added over a period of fifteen minutes. The reaction mixture is then stirred for fifteen minutes, and a solution of 422 g. (3.1 moles) of crystalline sodium acetate dissolved in 800 cc. of water is added over a period of five minutes. A yellow precipitate of diazoaminobenzene begins to form at once. Stirring is continued for forty-five minutes, keeping the temperature below 20° (Note 1). The yellow diazoaminobenzene is filtered on a 19-cm. Büchner funnel (Note 2), washed with 5 l. of cold water, and then sucked as dry as possible and spread out on a sheet of paper to dry (Note 3). The product thus obtained is dissolved in 4 l. of boiling ligroin (b.p. 60–90°) (Note 4), filtered, and allowed to cool to room temperature and stand overnight. When crystallization is complete, the yellow crystals are filtered on a 19-cm. Büchner funnel, washed with 500 cc. of cold ligroin (b.p. 60–90°), and dried at room temperature. The yield of yellow crystals melting at 92–94° is 242–251 g. (82–85 per cent of the theoretical amount) (Note 5). If a product of greater purity is desired, the diazoaminobenzene is dissolved in 4 l. of boiling ligroin (b.p. 60–90°) and crystallized as before. The recrystallized diazoaminobenzene weighs 204–218 g. (69–73 per cent of the theoretical amount) and melts at 94–96° (Note 6) and (Note 7).
2. Notes
1.
The temperature noted is not known to be the maximum temperature at which the reaction may be run.
2.
A
centrifuge of suitable size is preferable.
3.
A
rubber dam is fitted over the top of the Büchner funnel and held in place by rubber bands in order to remove as much of the water as possible.
4.
Prolonged heating of the
diazoaminobenzene with
ligroin causes decomposition. For this reason it is well to heat the
ligroin to boiling before it is added to the product to be crystallized. Solution is effected as rapidly as possible. If the crude
diazoaminobenzene is not dry, a layer of water will separate at the bottom of the flask. This should be removed as completely as possible before filtering the hot
ligroin solution.
5.
An additional crop of crystals weighing
20–25 g. and melting at
79–83° can be obtained by evaporating the mother liquors to 1 l. and chilling in an
ice bath.
6.
The size of the run may be halved; a run with half quantities gave
125 g. of product.
7.
Pure
diazoaminobenzene is described as faintly yellow needles melting at
100°. A procedure for the purification of
diazoaminobenzene and other aminoazo compounds has been described by Dwyer.
1
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3. Discussion
Diazoaminobenzene has been prepared by the action of
sodium nitrite on
aniline sulfate;
2 by the action of
sodium nitrite on
aniline hydrochloride;
3 by the action of
sodium nitrite and
sodium acetate on
aniline hydrochloride;
4 by the action of
ammonium nitrate and
hydrogen sulfide on
aniline hydrochloride in the presence of
iron;
5 by the action of
sodium nitrite and
potassium chromate or dichromate on
aniline;
6 and from
aniline and
amyl nitrite.
7
Diazoaminobenzene has also been prepared by the action of
nitrous acid gas on
aniline in alcohol;
8 by the action of
silver nitrite on
aniline hydrochloride;
9 and together with
phenylurea by the action of
nitrosophenylurea on
aniline in
methyl alcohol.
10 Niementowski and Roszkowski
11 have reported studies on the diazotization of
aniline,
aniline hydrochloride, and
aniline sulfate with
sodium nitrite and
silver nitrite. The procedure described is adapted from that of Fischer.
4
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ligroin
potassium chromate or dichromate
hydrochloric acid (7647-01-0)
methyl alcohol (67-56-1)
sodium acetate (127-09-3)
aniline (62-53-3)
iron (7439-89-6)
hydrogen sulfide (7783-06-4)
aniline hydrochloride (142-04-1)
sodium nitrite (7632-00-0)
nitrous acid (7782-77-6)
amyl nitrite (463-04-7)
ammonium nitrate
Phenylurea (64-10-8)
aniline sulfate
Diazoaminobenzene,
Triazene, 1,3-diphenyl- (136-35-6)
silver nitrite (7783-99-5)
nitrosophenylurea
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