Anilinium chloride

As described earlier one of the possible products from the AFO reaction is dihydroxyflavonols. Simpson and coworkers took advantage of this outcome in their synthesis of the flavonol rhamnocitrin (23). Chalcone 24 was subjected to the typical AFO conditions to deliver dihydroxyflavonol 25. The isolated product was further subjected to hydrogen peroxide to afford flavonol 25a in 30% yield. However, treatment of 25 with bismuth acetate, generated in situ from bismuth carbonate and acetic acid, gave 25a in 77% yield for a respectable 52% overall yield over two steps. 25a was then selectively demethylated with anilinium chloride to deliver rhamnocitrin (23). 

Cyclization takes place when tert-butylisocyanide, benzaldehyde, anilinium chloride, and carbonyl(dicyano)cyclopentadienyl ferrate are reacted, the carbene complex 42 being the result (95JOM(491)135). /50-butyraldehyde, tert-butyl isocyanide, ammonium hexafluorophosphate, and [(T -Cp)Fe(CO)(CN)2] give the cationic bis-carbene 43. 

An increased hydrogen ion concentration, that is a considerably greater amount of acid than the theoretical two equivalents of Scheme 2-1, is necessary in the diazotization of weakly basic amines. The classic example of this is the preparation of 4-nitrobenzenediazonium ions 4-nitroaniline is dissolved in hot 5-10 m HC1 to convert it into the anilinium ion and the solution is either cooled quickly or poured onto ice. In this way the anilinium chloride is precipitated before hydrolysis to the base can occur. On immediate addition of nitrite, smooth diazotization can be obtained. The diazonium salt solution formed should be practically clear and should not become cloudy on standing in the dark. Some practice is necessary, and details can be found in the books emphasizing preparative aspects (Fierz-David and Blangey, 1952 Saunders and Allen, 1985 in Houben-Weyl, Vol. E 16a, Part II, the chapter written by Engel, 1990). These books give a series of detailed prescriptions for specific examples and a useful review of the principal variations of the methods of diazotization. Such reviews have also been written by Putter (1965) and Schank (1975). 

C17-0023. Identify the major species and the dominant equilibrium for an aqueous solution of anilinium chloride (see Table 17-4 1. 

Moles of anilinium chloride) + 2(moles of malonic acid) = 0.002 983 9... 

Ammonium triselenimidate , see Ammonium 2,4,6-tris(dioxoselena) hexahydrotriazine-1,3,5-triide, 4586 Anilinium chloride, 2358 Anilinium nitrate, 2372 Anilinium perchlorate, 2360 Anisaldehyde, see 4-Methoxybenzaldehyde, 2951 m-Anisidine, see 3 -Methoxyaniline, 2813 o-Anisidine, see 2-Methoxyaniline, 2812... 

Ammonia is bubbled (30 min) through a cold suspension of (27) (4.0 g, 24.36 mmol) in dry chloroform (90ml) containing a catalytic amount of anilinium chloride. When all of the imidate has dissolved, the solution is allowed to warm to room temperature and stirred (19 h), during which time the product separates as an off-white solid. After filtering, washing with dry ether-dry chloroform, and drying in vacuo, (24) is obtained (3.1 Ig, 95%), m.p. > 300°C. 

Aniline is a colorless liquid. However, the aniline used in industry has a light yellow color. Aniline and water form two layers when mixed together. Aniline stays below the water because its density is higher (left tube). Aniline can react with HCI solution since it is a weak base (middle tube). If a sufficient amount of HCI is added, a colorless anilinium chloride (C6H5NH Ct) is formed (right tube). 

The anilinium ion (CgH5NH ) in anilinium chloride shows weak acid properties. If NaOH is added to anilinium chloride solution (left tube), the anilinium ions loses a proton to give aniline (middle and right tube)... 

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