Aryl-nitrosamine

Acyl-aryl-nitrosamines decompose in benzene by a radical and an ionic path, and the relative efficiency of a series of alkenes in promoting the ionic path has been considered. This is illustrated by the decomposition of N-nitrosoacetanil-ide (169) and benzenediazonium acetate by two competing routes to give benzyne (by acetate-induced elimination), which can be trapped as the furan adduct (170), and phenyl radicals by a chain reaction (Scheme 26). 

Ross and Chiarello (1979) have described a method for denitrosation of nitrosamines, such as dlalkylnitrosamines e.g. N-nitrosodimetl laminer etc., and complex aryl-alkyl nitrosamines, e.g. N-nitroso-N-(l-ethylpropyl)-3,4-dimethyl-2,6-dinitroaniline. The products of nitration and amination containing nitrosamlne as a substantial impurity are treated with an aldehyde or ketone in the presence of strong acids such as hydrochloric or hydrobromic acid. Under pressurized conditions at 105-110% for cme to two hours, the nitrosamlne is destroyed. The desired product can be recovered after neutralization of the excess acid. The equation shows the denitrosation of pendimethalin ... 

R, R1 = alkyl, aryl, COR, CONHR Fig. 3.2 N-N restricted rotation in N-nitrosamines. 

N-Hydroxy-N-nitrosamines with an aliphatic group at O2 produce a compound stable to aqueous acid and base (Fig. 3.4, 29) [158], whereas all other N-hydroxy-N-nitrosamines are susceptible to hydrolysis and appropriate 02-derivatives also render these materials vulnerable. The hydrolysis endpoint is the formation of nitroxyl (HNO) [which dimerizes to form nitrous oxide (N20)] and a C-nitroso compound. These products are formed from aryl [159] and alkyl bound unsubstituted diazenium-diolates as well as Oralkylated derivatives [160]. Studies of the solvolysis of Oi-alkyl derivatives are complicated by their tendency to decompose via competing radical pathways [161], but the Oi-benzyl derivatives are unique in that they hydrolyze back to the original synthetic precursors (Scheme 3.14) [162]. 

Bhide. Effects of tobacco-specific nitrosamines and snuff extract on cell proliferation and activities of ornithine decarboxylase and aryl hydrocarbon hydroxylase in mouse tongue primary epithelial cell cultures. J Cancer Res Clin Oncol 1989 115(6) 558-563. 

Although 3-amino-l,2,4-thiadiazoles (e.g. the 5-phenyl homolog) fail to yield nitrosamines under the usual conditions,126 5-nitrosamines are well known.81, 5,190,191 Thus, 3-alkoxy-,8 3-alkylthio-,85 3-dialkyl-amino-,87 and 3-alkylsulfonyl-5-amino-86 (243) as well as 3-aryl-5-arylamino-l,2,4-thiadiazoles,74 on treatment with the calculated quantity of sodium nitrite in dilute mineral acid, or concentrated formic acid, yield crystalline nitrosamines (244). Their unusual stability has permitted a close study of their formation and properties. 170 Their positive Liebermann reaction85,87,170 and the results of their methylation (outlined in the reaction scheme) show that nitro-sation occurs in the side-chain and not in the nucleus.170... 

Broadly, NOC are divided into two groups (a) /V-nitrosamines and (b) N-nitrosamides. In jV-nitrosamines, the two remaining substituent groups on the >N—N=0 atom can be either alkyl or aryl, or they can form the part of a heterocyclic ring (as in N-nitrosopyrrolidine). On the other hand, in N-nitrosamides, more correctly called N-acyl-N-nitroso compounds, one of these... 

Amino-5-aryl-l,3,4-oxadiazoles form stable N-nitrosamines (71c) which are converted into hydrazines (7ld) with zinc in acetic acid. Treatment of the hydrazine (71d) with nitrous acid yields the corresponding azide and with benzaldehyde a hydrazone is formed (B-61MI42300). On heating in benzene or in nitrobenzene, the nitrosamine (71c) undergoes the Gomberg-Bachmann reaction to yield 2,5-diaryl-l,3,4-oxadiazoles (73JCS(P1)1357). 

Methyl-aryl)- XI/1, 853 N-Nitroso- s.u. Nitrosamin N-Nitro- s.u. Nitramin (2-Phenyl-ethyl)- IV/lc, 119 Silyl- E18, 740 (Imin./Hydrosilylier.) N-Sulfinyl- Ell, 569... 

The nitrosamine (121) and especially diazonium salts (122) prepared from it, as well as their alkyl and aryl derivatives, are important synthetic intermediates (b-76MI4i200, p. 325). For conditions that decide between nitrosamine function or diazotization see (73jcS(P1)13S7). At room temperature or in concentrated hydrochloric acid nitrosamines derived from triazoles are unstable, and their decomposition products include chlorotriazoles (63LA(665)144) 5-nitrosamino-3-phenyl-l,2,4-triazole affords the 5-bromo compound with hydrobromic acid at 0 °C and reacts violently with hydroiodic acid (05lA(343)i). Thermal arylation with triazole nitrosamines is possible (73jcs(pi)i357). 

The nitrosation of secondary amines is reversible in acid solution, so A-nitrosamines may be hydrolized at low pH. Such hydrolysis is especially important for diaryl nitrosamines but also significant for aryl akyl nitrosamines. The NO liberated in the hydrolysis may react with the reduction product from the A-nitrosamine, the unsymmetrical hydrazine, with formation of amine and N2O [213,214] ... 

Chemicae Structure The name nitrosamines applies to a family of compounds that have an alkyl and an aryl group attached to the chemical group,... 

Chakradeo PP, Kayal J J, Bhide SV. 1993. Effect of benzo(a)pyrene and methyl(acetoxymethyl) nitrosamine on thymidine uptake and induction of aryl hydrocarbon hydroxylase activity in human fetal oesophageal cells in culture. Cell Biol Int 17(7) 671-676. 

N-Nitrosation. On activation by Ph3P-Br2 the electrophilic NO species is brought out of BU4NNO2. Both secondary and tertiary antines are converted by the reagent mix into nitrosamines, whereas arylhydrazines give aryl azides. ... 

Nitrosamines are derived from amines, and like aU Af-nitroso compounds, they have the N-N=0 functional group. They can be classified as volatile and nonvolatile. Volatile nitrosamines, in contrast to nonvolatile nitrosamines, can be removed from the matrix by distillation techniques and can be analyzed by gas chromatography (GC) without prior chemical derivatization. Alkyl and cyclic nitrosamines, which are volatile, have been intensively studied. The most commonly encountered nonvolatile nitrosamines are aryl compounds, hydroxylated compounds, and V-nitrosated amino acids. The structures of several nitrosamines are shown in Figure 12.1. 

Secondary aryl and alkyl amines react with a nitrosonium ion to form nitrosamines rather than diazonium ions. The mechanism of the reaction is similar to that for the reaction of a primary amine with a nitrosonium ion, except that the reaction stops at the ni-trosamine stage. The reaction stops because a secondary amine, unlike a primary amine, does not have the second proton that must be lost in order to generate the diazonium ion. 

Figure 10.25 Twenty-nine specific toxicophores for mutagenicity as identified by Kazius el al. (Kazius, J-, et al. Derivation and validation of toxicophores for mutagenicity prediction. J. Med. Chem. 2005, 48, 312-320.) (A) Specific aromatic nitro, (B) specific aromatic amine, (C) aromatic nitroso, (D) alkyl nitrite, (E) nitrosamine, (F) epoxide, (G) aziridine, (H) azide, (I) diazo, (J) triazene, (K) aromatic azo, (L) unsubstituted heteroatom-bonded heteroatom, (M) aryl hydroxylamine, (N) alkyl halide, (O) acyl halide, (P) N- or 5-mustard, (Q) polycyclic aromatics, (R) bay-region, (S) K-region, (T) sulphonate-bonded C, (U) unsaturated aldehyde, (V) alkyl A-nitro, (W) diazonium, (X) p-propiolactone, (Y) unsubstituted a,p unsaturated alkoxy, (Z) l-aryl-2-monoalkyl hydrazine, (AA) aromatic methylamine, (AB) aryl hydroxylamine ester, and (AC) polycyclic planar system.

Szyrszyng. M. Nowak. E. Gdaniec, M. Milewska, M.J. Herman, A. Polonski, T. Circular dichroism spectra of the achiral guest A-aryl-A-nitrosamines included in the crystal host matrices of cholic acid. J. Org. Chem. 2001, 66 (22) 7380-7384. 

Symmetrical dialkyl-nitrosamines Methyl alkyl nitrosamines Cyclic nitrosamines Aryl-alkyl and diaryl nitrosamines... 

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