2-Chloroacetanilide

De la Mare and Hassan254 obtained second-order rate coefficients (in parenthesis) for the following 4-methylacetanilide (1.53), 2-methylacetanilide (0.193), 2,6-dimethylacetanilide (0.0118), acetanilide (0.93), 4-acetamidodiphenyl (0.248) and 1,4-diacetamidobenzene (0.231) the results for the acetanilides demonstrated the effect of steric hindrance to coplanarity thereby inhibiting resonance of the nitrogen lone pair with the aromatic ring. The rate coefficients for chlorination of 3-chloroacetanilide (0.215), 4-chloroacetanilide (0.010) 3-nitroacetanilide (6.7 x 10 5) and phenyl benzoate (3.2 x 10-6) have also been measured258,261. 

Biological. In an anaerobic medium, the bacteria of the Paracoccus sp. converted 4-chloroaniline to l,3-bis(/t-chlorophenyl)triazene and 4-chloroacetanilide with product yields of 80 and 5%, respectively (Minard et al., 1977). In a field experiment, [ C]4-chloroaniline was applied to a soil at a depth of 10 cm. After 20 wk, 32.4% of the applied amount was recovered in soil. Metabolites identified include 4-chloroformanilide, 4-chloroacetanilide, 4-chloronitrobenzene, 4-chloronitrosobenzene, 4,4 -dichloroazoxybenzene, and 4,4 -dichloroazobenzene (Freitag et al, 1984). 

Biological. Under aerobic conditions, the yeast Rhodosporidium sp. metabolized p-chloronitrobenzene to 4-chloroacetanilide and 4-chloro-2-hydroxyacetanilide as final major metabolites, intermediate compounds identified include 4-chloronitrosobenzene, 4-chlorophen-ylhydroxylamine, and 4-chloroaniline (Corbett and Corbett, 1981). 

The photochemistry of 4-chloroanilines in methanol, dioxane-water and diox-ane-methanol solvents has been investigated for more than thirty years by Latowski185,186. Large quantum yields of HC1 formation (hci) have been observed for the photolysis of 91a in protic solvents (e.g. Hci = 0.78 in methanol at 254 nm). However, the values of 4>hx are relatively small for 4-bromoaniline (HBt = 0.19), 4-iodoaniline (cbm = 0.29), 2-chloroaniline (hci < 0.02) and 3-chloroaniline (hci = 0.02) under the same condition. N-Acetylation of 91a to 4-chloroacetanilide also inhibits the photolytic process. In conjunction with the solvent- and concentration-dependent photolysis rates of 91a, these results indicate an electron-transfer mechanism for the photochemical reaction electron transfer occurred from an excited 91a to an unexcited 91a molecule, followed by ionization reactions. However, recent analysis of photoproducts from 91a in water/methanol mixtures has shown that benzidine (92) is a major product along with aniline (equation 29)187. As a result, a carbene mechanism that leads to the formation of aniline radicals was put forward in analogy to the photochemistry of 4-halophenols188,189. For example, the photolysis of 91a in aqueous solution first results in the transient species carbene 93 followed by the formation of the aniline radical 94 that was observed as the primary product (Scheme 13)190. In addition to la and 92, other identified secondary products include 4-aminodiphenylamine, 2-aminodiphenylamine, hydrazobenzene, 4-chloronitrosobenzene and 4-chloronitrobenzene, but they are all in low yields191. 

Although the biodegradation of phenols and anilines is well established, these are relatively toxic compounds and some microorganisms detoxify them by acylation as an alternative to biodegradation. For example, acetylation of pentachlorophenol has been observed (Rottt et al. 1979), and acetylation of substituted anilines has been established 4-chloroaniline is converted into 4-chloroacetanilide by Fusarium oxysporum (Kaufman et al. 1973) and 2-nitro-4-aminotol-uene that is produced from 2,4-dinitrotoluene by a species of Mucrosporium sp. (McCormick et al. 1978) is converted into 3-nitro-4-methylacetanilide. All these neutral compounds may plausibly be assumed to be less toxic than their precursors. 

Lenk, W, and M. Riedl. 1989. N-Hydroxy-N-arylacetamides. V. Differences in the mechanism of haemoglobin oxidation in vitro by N-hydroxy-4-chloroacetanilide andN-hydroxy-4-chloroaniline. Xenobiotica 19 453-475. 

Chloroacetanilide was recovered in 28% yield No conjugate reduction product was obtained... 

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