Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

ETHYL NITEITB 147
solution and then several times with water. After separation of
the two layers, the reaction product is clarified and dried over a
little calcium chloride in a small conical flask. The dried liquid is
then distilled at 50-60 mm. pressure (cf. p. 24) into a well-cooled
receiver. The bulk of the liquid passes over at about 30° as a
yellow oil. Yield 75 per cent of the theoretical.
The esters of nitrous acid are characterised by their high velocities
of formation and hydrolysis. They are almost instantaneously decomposed
by mineral acids and in the method of preparation given this
has been taken into account. The slightest excess of hydrochloric
acid must be avoided. Advantage is taken of this property of the
alkyl nitrites in all cases where it is desired to liberate nitrous acid in
organic solvents (in which metallic nitrites are insoluble). Examples :
addition of N2O3 to olefines, preparation of solid diazonium salts
(p. 286), production of isonitroso-derivatives from ketones by the action
of HN02. This synthesis is often also carried out in the manner of
the acetoacetic ester synthesis, with ketone, alkyl nitrite, and sodium
ethylate ; the sodium salt of the isonitrosoketone is formed (cf. in this
connexion p. 259) :
R—CH2 R0.N:0 R—C:NONa
| + —>• | + 2R0H.
R_CO RONa R—C:O
The elegant synthesis of sodium azide from hydrazine and alkyl
nitrite is carried out in the same way (Stolle) :
N \
H2N—NH2 + RO—N=O + RONa —> II >N.Na + 2 ROH + H2O .
W
Ethyl nitrite is often used in preference to isoamyl nitrite because
the removal of the amyl alcohol produced from the latter may be
troublesome on account of its high boiling point (136°).
Ethyl Nitrite.—To the mixture of the above sodium nitrite solution
with 60 c.c. of spirit, contained in a distilling flask and cooled
in ice, 42 c.c. of concentrated hydrochloric acid are gradually added
drop by drop. During the addition of the acid the flask is shaken.
The flask is then attached to an efficient condenser, through which
ice-water may be run with advantage ; the receiver (a filter flask)
should stand in a freezing mixture. After addition of the acid the
ethyl nitrite is distilled by heating the flask first at 25°, finally at
40°, in a basin of warm water. After being dried for a short time
over potassium carbonate the product is sufficiently pure for most