In a
5-l. two-necked flask, fitted with a
mechanical stirrer, a
reflux condenser, a
thermometer, and a
separatory funnel, are placed an aqueous solution of
348 g. (5 moles) of hydroxylamine hydrochloride (Org. Syn. Coll. Vol. I, 1941, 318) in 600 cc. of cold water and
460 g. (4 moles) of heptaldehyde (Note
1). Stirring (Note
2) is started, and a solution of
265 g. (2.5 moles) of anhydrous c.p. sodium carbonate in 500 cc. of water is added at such a rate that the temperature of the reaction mixture does not rise above 45°. Stirring is continued at room temperature for an hour after the addition of the
sodium carbonate solution is complete.
The oily layer on top of the reaction mixture is separated and washed with two 100-cc. portions of water (Note
3). The washed product is transferred to a
1.5-l. modified Claisen flask and distilled under reduced pressure from an
oil bath. The first fraction contains a very small amount of water along with a mixture of
heptanonitrile and
heptaldoxime. The product is collected at
103–107°/6 mm. (temperature of the oil bath, 140–147°) (Note
4). The yield is
420–480 g. (
81–93 per cent of the theoretical amount). The product solidifies slowly on cooling and melts at
44–46°. It can be used for reduction to
n-heptylamine (p. 318) without further purification.
The product can be purified by recrystallization from
60 per cent ethyl alcohol, using approximately 70 cc. of the solvent to 25 g. of the distilled product. One such recrystallization (Note
5) gives white leaflets melting at
53–55° (Note
6) and (Note
7). The yield of recrystallized material from a single run is
315–320 g.