The introduction of Nicotinic Anhydride

After the accession of phosgene the admixture is afflicted at allowance temperature for 45 minutes, acrimonious to the baking point, and filtered beneath hardly bargain burden (Note 6) while hot. The triethylamine hydrochloride block (Note 7) is done on the clarify with three 25-ml. portions of balmy benzene (60°). The accumulated clarify and washes are transferred to a 500-ml. round-bottomed alembic and evaporated to boredom on a rotary evaporator at low temperature and pressure. The dry balance is broiled with 75 ml. of anhydrous benzene (Note 2), and the admixture is filtered while hot. The triethylamine hydrochloride block (Note 7) is done with two 5-ml. portions of algid benzene, and the clarify and washes are accustomed to angle at 20° for 2–3 hours. The apparent artefact is calm on a filter, done with two 4-ml. portions of algid anhydrous benzene, and broiled in a vacuum. The crop of nicotinic anhydride, m.p. 122–125° (Note 8), is 6.25 g. (68%). The accumulated clarify and washes are evaporated to boredom on a rotary evaporator. The balance is broiled with 175 ml. of a admixture of benzene and cyclohexane (2:3) (Note 2), and a baby bulk of baffling actual is removed by filtration of the hot admixture (Note 6). The clarify is stored at 5° for 18 hours (Note 9); the apparent drop is collected, done with 3 ml. of algid benzene-cyclohexane mixture, and broiled in a vacuum. An added 2.4 g. (25%) of achromatic product, m.p. 122–123°, is appropriately obtained. The absolute crop of nicotinic anhydride is 8.05–8.65 g. (87–93%).The present adjustment is that declared by Rinderknecht and Ma.3 It is appropriately applicative to a array of added heterocyclic, aromatic, and aliphatic anhydrides.4,5 Nicotinic anhydride was aboriginal able by acknowledgment of nicotinoyl chloride with sodium nicotinate,6,7 and added afresh by acknowledgment of potassium nicotinate with oxalyl chloride in anhydrous benzene.2
Note:1. Nicotinic acerbic supplied by Matheson, Coleman and Bell yielded a achromatic anhydride; U.S.P. brand actual gave a hardly buff-colored product.
2. Benzene and cyclohexane are afresh distilled and stored over sodium wire or calcium hydride.
3. Nicotinic anhydride is acutely acute to moisture; all glassware is accordingly broiled brief in an oven at 200° afore use.
4. Triethylamine is afresh distilled and stored over potassium hydroxide pellets.
5. A 12.5% band-aid of phosgene in benzene is accessible from Matheson, Coleman and Bell.
6. It is capital to backpack out filtration beneath alone hardly bargain burden in adjustment to abbreviate evaporation, cooling, and condensate in the clarify bowl and funnel.
7. The crop of triethylamine hydrochloride acquired in this and consecutive extractions amounts to over 96% of that expected.
8. Melting credibility were bent in capillary tubes and are corrected. Reported:2 123–126°.
9. Rigorously anhydrous altitude are capital throughout this action and the alembic have to be air-tight.
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