vogel_practical_ochem_3.pdf

120] ALIPHATIC COMPOUNDS 417
the oil bath also. Permit the reaction to proceed without further heating
until the evolution of gas subsides (60-90 minutes) ; then raise the temperature
of the bath to about 160° and maintain it at this temperature
until the evolution of gas almost ceases (2* 5-3* 5 hours). The reaction
is then complete.
When the reaction mixture has cooled somewhat, insert a separatory
funnel into the neck of the flask and arrange the reflux condenser for
downward distillation (as in Fig. 111,35, I); fit the lower end of the
condenser into the neck of a distilling flask or a filter flask (1) and attach
the side arm by means of rubber tubing to an inverted funnel immersed
to a depth of 1 cm. in 190 ml. of concentrated hydrochloric acid in a
beaker. All joints must fit well as trimethylamine is very volatile and
can easily be lost. Place a solution of 220 g. of sodium hydroxide in
400 ml. of water in the separatory funnel and allow it to run slowly into
the warm reaction mixture. The amine distils and collects largely in
the hydrochloric acid. Finally, heat the mixture for about 15 minutes
to ensure that all the trimethylamine has been expelled from the reaction
flask. Evaporate the hydrochloric acid solution on a water bath ; the
trimethylamine hydrochloride gradually crystallises out and is filtered
off from time to time (2) ; it is dried for a few minutes at 100-105° and
preserved in a tightly stoppered bottle. The solid (ca. 14 g.) obtained
by evaporation to dryness may be tinged slightly yellow. The yield is
about 150 g. (3).
Notes.
(1) The object of the intermediate flask is to trap any water which may distil
with the amine ; this water is generally coloured yellow and if allowed to pass into
the hydrochloric acid in the receiver will contaminate the product.
(2) The most satisfactory method of drying is by centrifuging : the salt is
hygroscopic.
(3) The absence of ammonium chloride and methylamine hydrochloride may be
shown by the complete solubility of the product in chloroform.
111,120. n-AMYLAMINE
Equip a three-necked 1-litre flask with a dropping funnel, an efficient
mechanical stirrer and a reflux condenser (Fig. II, 7, 11). Place 55 g. of
clean sodium and 200 ml. of sodium-dried toluene in the flask, heat the
mixture until the toluene commences to boil, and then stir the molten
sodium vigorously thus producing an emulsion. Run in through the
dropping funnel a mixture of 33 g. (41-5 ml.) of n-butyl cyanide (Section
111,113) and 60 g. (76 ml.) of absolute ethyl alcohol during 1 hour.
During the addition and the subsequent introduction of alcohol and of
water, the stirring should be vigorous and the temperature adjusted so
that the refluxing is continuous ; the heat of reaction will, in general,
be sufficient to maintain the refluxing. After the n-butyl cyanide solution
has been added, introduce gradually a further 60 g. (76 ml.) of absolute
alcohol. In order to destroy any residual sodium, treat the reaction
mixture slowly with 40 g. (50 ml.) of rectified spirit and then with 20 g.
of water. Steam distil the contents of the flask (compare Fig. //, 41, 1)
(about 2 hours) and add 40 ml. of concentrated hydrochloric acid to the
distillate. Separate the toluene layer ; distil the aqueous layer, which