Acetanilides dimer

Acetanilide, electrophilic aromatic substitution of, 939-940 Acetate ion, bond lengths in, 43 electrostatic potential map of, 43, 53, 56, 757 resonance in, 43 Acetk acid, bond angles in, 755 bond lengths in, 755 dimer of, 755 dipole moment of, 39 electrostatic potential map of, 53, 55... 

In a 500-cc. round-bottomed, three-necked flask fitted with a reflux condenser, dropping funnel, and a mercury-sealed stirrer (Note 1) is placed a solution of 46 g. (0.5 mole) of dry aniline in 125 cc. of pure dry benzene. Stirring is started, and a solution of 42 g. (0.5 mole) of ketene dimer (p. 64) in 75 cc. of pure dry benzene is added dropwise over a period of half an hour. The reaction mixture is then heated under reflux on the steam bath for one hbur. After the major portion of the benzene has been removed by distillation from the steam bath, the remainder is removed under reduced pressure. The residue is dissolved in 500 cc. of hot 50 per cent aqueous alcohol from which the aceto-acetanilide separates on cooling. The mixture is cooled to 0° before filtration. A second crop of crystals can be obtained by adding 250 cc. of water to the mother liquor and cooling again (Note 2). The total yield of product, m.p. 82-83.5°, is 65 g. (74 per cent of the theoretical amount). Further purification by recrystallization from 300 cc. of 50 per cent alcohol yields 55 g. of a product which melts at 84-85°. 

Lutski directed attention to the H bond in simpler molecules by proposing that the influence of ethanol solvent on the UV spectrum of an orthoh.y6.voxy keto- or nitro aromatic provides a criterion for an j n/ramolecular H bond (1287, 1285). Brieglieb and Strohmeier were able to detect the influence of H bonded dimer formation on the spectra of acetic acid vapor at different temperatures (near 2100 A) (279). There have followed many valuable studies directed at the effect of H bonding on the electronic transitions of acids such as phenols, aniline (1483, 1481, 2056), benzoic acid and derivatives (2076, 1998, 671, 190), acetanilides (2075, 2074), HF (1771, 1770), naphthols (1479, 1484), sulfinic acids (521), and amides (1436). The most extensive work, that of Nagakura, Baba, and co-workers, is of particular importance because it led to theoretical consideration of the nature of the H bond (see Section 8.3.2). (See adso 2056,. 1418, 1850.)... 

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