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Organic syntheses - Roger A.

Roger A. Organic syntheses - Chapman, 1936. - 110 p.
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The mixture is cooled, and the solid addition product is decomposed by
adding 600 cc. of water and shaking until all the solid material has
disappeared. The benzene and benzaldehyde are removed by steam
distillation; the residual liquor, after cooling, is treated with 15-20
cc. of benzaldehyde and left overnight. The resin and benzalazine are
filtered off (Note 4).
The filtrate is evaporated under reduced pressure on a water bath
until a semi-crystalline mass remains, which is further desiccated by
evaporating twice under reduced pressure with 50-cc. portions of absolute
ethyl alcohol. The resulting crystalline cake is crushed with 50 cc. of
absolute ethyl alcohol, filtered, and the process repeated. The white,
crystalline product is almost pure methylhydrazine sulfate and contains
very little hydrazine sulfate. After drying in a vacuum desiccator over
calcium chloride, the yield is 105-110 g. (76-80 per cent of the
theoretical amount). For purification, the sulfate is dissolved in about
250 cc. of boiling 80 per cent ethyl alcohol, and any undissolved
material (chiefly hydrazine sulfate) is filtered off. On cooling, the
methylhydrazine sulfate separates in white plates, which are filtered
with suction and washed with a little absolute alcohol. After drying over
calcium chloride, the first fraction, m.p. 141-142, weighs 70-75 g. (51-
54 per cent of the theoretical amount) (Note 5).
2. Notes
1. The benzaldehyde should be freed of benzoic acid by shaking
with aqueous sodium carbonate solution.
2. The mixture is stirred vigorously during the reaction, and one
or two stout glass rods are clamped in the flask to act as baffles and to
break up the lumps of benzalazine.
3. Since dimethyl sulfate is very toxic, care should be exercised
to avoid spilling the liquid or inhaling the vapor of the reaction
mixture. Ammonia is a specific antidote.
4. Unreacted hydrazine sulfate is removed by conversion to
benzalazine. The filtrate should not give an appreciable precipitate when
mixed with 5 cc. of benzaldehyde and left for four hours.
5. From the mother liquors about 12 g. of less pure material,
m.p. 133-136, can be recovered.
3. Methods of Preparation
The procedure given above is essentially the method of Thiele.1
Methylhydrazine has also been prepared by reduction and subsequent
hydrolysis of nitrosomethylurea,2 nitromethyl-urethane,3 and
nitrosomethylamine sulfonic acid;4 and by methylation of hydrazine
hydrate with methyl iodide5 or di-azomethane.(r)
1 Thiele, Ann. 376, 244. (1910).
2 Brtining, ibid. 253, 7 (1889).
3 Backer, Rec. trav. chim. 31, 193 (1912).
4 Traube and Brehmer, Ber. 52, 1286 (ipip).
6 Harries and Haga, ibid. 31, 56 (1898).
6 Staudinger and Kupfer, ibid. 45, 501 (1912).
P-NO2C6H4CH3 + Br2 -> ^NOzCeHiCH^Br + HBr
Submitted by G. H. Coleman and G. E. Honeywell.
Checked by Wallace H. Cabotiiers and W. L. McEwen.
1. Procedure
In a i-l. three-necked flask is placed 300 g. (2.19 moles) of
technical ^-nitrotoluene (m.p. 51-520). The flask is fitted with a
liquid-sealed stirrer, reflux condenser, and a separatory funnel arranged
so that the stem reaches nearly to the bottom of the flask. The condenser
is provided with a tube for disposing of the hydrogen bromide evolved
(Org. Syn. 14, 2). The flask is heated in an oil bath at 145-150 (Note
1), and 368 g. (118 cc., 2.3 moles) of bromine is added dropwise over a
period of two hours (Note 2).
After all the bromine has been added, the heating and stirring are
continued for ten minutes. While still liquid, the contents of the flask
(Note 3) are poured into a 5-I. round-bottomed flask containing 41. of
hot ligroin (b.p. 90-100), and 15 g. of decolorizing carbon (Norite) is
added. The material is brought into solution by heating on an electric
hot plate, and after boiling for ten minutes the solution is filtered
rapidly with suction (Note 4). After cooling to 20, the crystals are
filtered with suction, pressed thoroughly, and washed with two 50-cc.
portions of cold ligroin. The crude product, m.p. 94-97, weighs 280-315
g. (59-66 per cent of the theoretical amount) and is sufficiently pure
for some purposes. For purification, this material is dissolved in 3-3.5
1. of hot ligroin, boiled with 10-15 g. of decolorizing carbon, and
filtered with suction (Note 4). After cooling in an ice bath the crystals
are collected on a Buchner funnel, pressed, and
washed with two 25-cc. portions of cold ligroin. The pale yellow product
melts at 97.5-99 and weighs 250-280 g. (53-59 per cent of the
theoretical amount) (Note 5).
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