In a 5-l. round-bottomed flask is placed 4 kg. (2816 cc.) of c.p. concentrated nitric acid (sp. gr. 1.42) (Note 1). To this is added, in 25-cc. portions, 210 g. (1.23 moles) of nicotine (Note 2). The addition should be made carefully in order that local heating may not occur and material be lost. After each addition of nicotine, the flask should be shaken in order to insure a homogeneous solution. The addition of the nicotine causes the temperature of the liquid to rise somewhat but not sufficiently to cause evolution of nitrogen dioxide. The flask is placed on a steam bath under a hood and heated until the liquid reaches a temperature of 70°. It is then removed and the reaction allowed to continue spontaneously (Note 3), sufficient heat being evolved to cause the liquid to boil. The boiling ceases after one hour, but the flask is replaced upon the steam bath for ten to twelve hours, during which time there is a more or less continuous evolution of oxides of nitrogen.

The contents of the flask are then poured into an evaporating dish and evaporated almost to dryness on the steam bath (about ten hours). The purification which follows is best carried out with the product of two runs such as have been described above.

After the evaporation of most of the liquid, the nicotinic acid nitrate from two runs is transferred to a 1.5-l. beaker, 400 cc. of distilled water is added (Note 4), and the mixture is heated until complete solution results. On cooling, the nicotinic acid nitrate separates as yellow granular crystals and is filtered off. To obtain it absolutely pure, it may be recrystallized in a way similar to that just described but with the use of animal charcoal. It contains one molecule of water of crystallization and has a melting point of 190–192° (corr.). The yield is 420–460 g. 83–91 per cent of the theoretical amount).

The 420–460 g. of crude nicotinic acid nitrate from two runs (not necessarily dry) is dissolved in 900 cc. of boiling water in a 3-l. beaker, and 800 g. of crystalline disodium phosphate (Na₂HPO₄ · 12H₂O) is added with constant stirring. The resulting thick mixture is stirred and heated almost to boiling for five minutes and then allowed to cool. The mixture is finally chilled to 0° by an ice bath. It is well to stir occasionally during the crystallization to prevent the formation of too solid a cake of crystalline material. The nicotinic acid is filtered off upon a 15-cm. Büchner funnel and washed with three 100-cc. portions of cold water.

The yield is 260–300 g. of material containing a small amount of mineral salts but otherwise nearly pure. It can be purified further by recrystallization from 2.5 to 3.5 l. (Note 4) of hot water, 150–180 g. of material, which melts at 230–232° (corr.), being obtained. The yield of recrystallized material is 50–60 per cent of the theoretical amount, based upon the nicotine employed.

The recrystallization is the least satisfactory part of this procedure and involves the greatest apparent loss of material; the product before recrystallization is sufficiently pure for most purposes. By evaporation of the mother liquors, 40–45 g. of pure nicotinic acid may be obtained, making the total yield of pure material 190–225 g. (63–74 per cent of the theoretical amount); in addition, a small amount of somewhat less pure material is recovered (Note 5).