ACONITINE. 
§ 436.1 
vapour. Aconitine also may, by heating with dilute acids, be made to 
readily yield benzoic acid, an acid easy of identification. Aconitine dis¬ 
solved in nitric acid, evaporated to dryness, and then treated with 
alcoholic potash, gives off an unmistakable odour of benzoic ester. 
Should there be sufficient aconitine recovered to convert it into the 
gold salt, the properties of the gold salt (that is, its melting-point, and 
the percentage of gold left after burning) assist materially in the 
identification. 
A minute quantity.of aconitine dissolved in water, acidified with acetic 
acid, and a particle of KI added and the solution allowed to evaporate, 
gives crystals of aconitine hydriodide, from which water will dissolve 
out the KI. Iodine water gives a precipitate of a reddish-brown colour 
in a solution of 1 : 2000. 1 
The chemical tests are supplementary to the physiological; if the 
alkaloidal extract does not give the tingling, numbing sensation, aconitine 
cannot be present. 
§ 436. Benzoyl-aconine (“ isaconitine” ), C 32 H 45 NO n , is obtained 
from aconitine by heating an aqueous solution of the sulphate or hydro¬ 
chloride in a closed tube at 120°-130° for two or three hours, a molecule 
of acetic acid (9-3 per cent.) being split off, and benzoyl-aconine left. 
It may be separated from the mixed alkaloids of the Aconitum 
napellus by dissolving in a 5 per cent, solution of hydrobromic acid 
(excess of acid being avoided), precipitating with a slight excess of 
ammonia, and shaking out with ether. The residue left after the ether 
is evaporated chiefly consists of aconitine ; it is dissolved in just suffi¬ 
cient hydrobromic acid and the exactly neutral hydrobromate solution 
allowed to evaporate spontaneously in a desiccator ; crystals of aconitine 
hydrobromide separate out, the mother-liquor containing some benzoyl- 
aconine and “ homonapelline.” The aqueous solution which has been 
exhausted with ether is now shaken out with chloroform. This chloro¬ 
form solution contains most of the benzoyl-aconine, and on separation 
the residue is dissolved in just sufficient hydrochloric acid to form a 
neutral solution ; this solution is concentrated on the water-bath with 
constant stirring, crystals of the hydrochloride form, and are filtered off 
from time to time and washed with a little cold water, the washings 
being added to the original liquid ; the different fractions are mixed 
together, and the process repeated until they have a melting-point of 
268°. Benzoyl-aconine is obtained from the hydrochloride by precipi¬ 
tating the aqueous solution by the addition of dilute ammonia, and 
extracting the solution with ether ; the solution in ether is washed 
with water, dried by means of calcium chloride, and then distilled off. 
Benzoyl-aconine is left as a transparent, colourless, non-crystalline 
varnish of a melting-point near 125°. 
1 A. Jurgens, Arch. Pharm. (3), xxiv. 127, 128. 
24 
