Amination with Nitroso Compounds

Reaction of amines with nitroso compounds (Mills)... 

While the condensation of amines with nitroso compounds appears to have wide applicability in the benzene series, it seems to lead to complex dye molecules in the naphthalene series. A method has been developed using a somewhat complex reaction between thionylamines and substituted hydroxylamines which does produce azo compounds derived from naphthalenes. This synthesis is of particular interest because it helped to settle the question whether true naphthylazo compounds with hydroxyl groups could exist [36]. 

Some reference to the use of nitrous acid merits mention here. Primary aromatic amines yield diazonium compounds, which may be coupled with phenols to yield highly-coloured azo dyes (see Section IV,100,(iii)). Secondary aromatic amines afford nitroso compounds, which give Liebermann a nitroso reaction Section IV,100,(v). Tertiary aromatic amines, of the type of dimethylaniline, yield p-nitroso derivatives see Section IV,100,(vii). ... 

Complexes of the lanthanides with amine oxides, nitroso compounds, and nitroxide radicals fall under this category. However, only the complexes with the amine oxides have received wide attention. Four comprehensive reviews have appeared on the complexes of amine oxides with various metal ions 142-145). Only a few complexes of the lanthanides have been quoted in these reviews. 

Further complications of the reduction of aromatic nitro compounds are the possibility of complete reduction to aromatic amines (which may condense with nitroso compounds to give the desired azo compounds), reduction of azo compounds to the corresponding hydrazo compounds, followed by a benzidine (or semidine) rearrangement. It is clear, therefore, that the level of reducing agent used and other reaction conditions are quite critical. 

Oxygen difluoride was first synthesized in 1927 and several publications deal with its preparation.16 19 Oxygen difluoride transforms various aliphatic amines to nitroso compounds 14 in low-temperature reactions.20... 

Schenk et al. have used the a-chloro nitroso compound 93 for the reaction with cyclopentene 98 in order to solve the problem with the instability of the allyl amine product formed from the reaction with nitroso compounds [56c]. The product formed, 99, rearranges to the stable nitrone hydrochloride salt 100, which is easily hydrolyzed to the hydroxylamine 101 (Eq. (23)). 

Peroxide complexes of molybdenum(VI) are intermediates in industrially important epoxidation reactions. The so-called Mimoun-type complexes [Mo 0(02)2LaxLeq]° " (12) generally exhibit pentagonal-bipyramidal structures, with an axial 0x0 group trans to Lax and Leq, and two peroxo groups in the equatorial plane. These complexes are effective reagents for the selective oxidation of alcohols to aldehydes, amines to nitroso compounds, sulfldes to sulfoxides and then to sulfones, phenols to o-quinones, and in the sulfoxidation of thianthrene-5-oxide. 

Reactivity With Nitroso Compounds. Functionalization of diene based rubbers with aromatic nitroso compounds bearing aminic or phenolic moieties 174, like with iV,A-diethyl-4-nitrosoaniline, 4-nitrosodiphenylamine, 4-nitrosodiphenylhy-droxylamine or 4-nitrosophenol represents an effective way for the synthesis of polymer-bound antioxidants [233], The respective nitroso compound can be mixed with rubbers during compounding or with concentrated rubber latexes. The chemical attachement of stabilizing active moieties takes place during subsequent... 

In the secondary amine there are not two remaining ammonia hydrogens and the reaction cannot take place as with primary amines. Instead, the one remaining ammonia hydrogen unites with the hydroxyl of the nitrous acid forming water, and the other product is the nitroso amine. These nitroso compounds are able to be distilled and can be reconverted into the amine by means of hydrochloric acid. 

Nitroso compounds and hydroxylamines can be reduced to amines by the same reagents that reduce nitro compounds (19-45). Reaction with CuCl, and then phe-nylboronic acid (p. 815), also reduces nitroso compounds to the amine.A hydroxylamine can be reduced to the amine with CS2 in acetonitrile. Indium metal in EtOH/aq. NH4CI reduces hydroxylamines to the amine. V-Nitroso compounds are similarly reduced to hydrazinesm R2N—NO R2N-NH2. ... 

Oxidants suitable for the partial oxidation of amines to nitroso compounds are peroxy acids Caro acid, which is prepared in situ from potassium persulfate and sulfuric acid [195, 199 potassium peroxysulfate (Oxone) [295] peroxyacetic acid [i53], and peroxybenzoic add [1186], 3-Nitro-o-toluidine [195] and 5-nitro-o-toluidine [199] in aqueous-alcoholic solutions, when treated with a mixture of potassium persulfate and concentrated sulfuric acid, give 3-nitro-2-nitrosotoluene and 5-nitro-2-nitrosotoluene in respective yields of 60 and 55-66%. Organic peroxy acids convert 2,6-dihaloanilines into 2,6-dihalonitrosobenzenes (equation 497) [753, 1186]. p-Phenylenediamine (1,4-diaminobenzene) is oxidized by Oxone (2KHS05 KHS04 K2S04) in an aqueous suspension at room temperature to p-dinitrosobenzene in a quantitative yield [205]. 

Oxidation of Primary Aromatic Amines to Nitroso Compounds with Peroxyacetic Acid [753] ... 

Oximes are tautomeric with nitroso compounds. Oximes are generally reduced to amines in a reaction in which the NO bond is cleaved before the hydrogenation of the ON double bond occurs. In acid solution the reaction is as in Eq. 15 [60] ... 

The last-mentioned disadvantage of deaminations of amines with nitrosating compounds in aqueous and other protic solvents is, of course, not present if N-nitroso amides and related compounds discussed earlier (7.10, and footnote on p. 246, concerning White s pioneering work) are used in aprotic solvents. 

The reduction of nitroaromatics in anaerobic systems has received considerable attention because of their importance as agrochemicals, munitions, textile dyes, and dye intermediates. The reaction products resulting from the reduction of nitroaromatic compounds are aromatic amines. The formation of aromatic amines occurs through a series of electron transfer reactions with nitroso compounds and hydrox-ylamines as even-electron intermediates (Equation 3.21). Typically, these intermediates are more reactive than the parent nitroaromatic compound, and do not persist to any great extent in reducing environments. 

Primary amines RNH2 (R = i-Pr, /-Bu, t-Bu or cyclohexyl) react with the carbamate Et02CN=CCl2 to yield the carbodiimides Et02CN=C=NR. A new method of preparing imines is to add a carbonyl compound (2,6-dimethylcyclohexanone, 2-tetralone, 2-decalone etc.) to a preformed complex of a primary amine (t-butylamine, cyclohexylamine, benzylamine or 1-phenylethylamine) and titanimn(IV) chloride suspended in hexane or octane. Primary amines R NH2 (R = t-Bu, N=C, Tos or phthalimido) react with nitroso compounds R NO (R = r-Bu, pyrrolidin-l-yl, Ph or 2-MeCC6H4) in the presence of the hypervalent iodine compound Phi (OAc)2 to give... 

Scheme 4.103 Amination of Oppolzer sultams 92 by reaction of the potassium enolates with nitroso compound 486. Cleavage of the auxiliary and model 491 as a rationale of the stereochemical outcome.

Secondary and tertiary amines are not generally prepared in the laboratory. On the technical scale methylaniline is prepared by heating a mixture of aniline hydrochloride (55 parts) and methyl alcohol (16 parts) at 120° in an autoclave. For dimethylaniline, aniline and methyl alcohol are mixed in the proportion of 80 78, 8 parts of concentrated sulphuric acid are added and the mixture heated in an autoclave at 230-235° and a pressure of 25-30 atmospheres. Ethyl- and diethyl-anihne are prepared similarly. One method of isolating pure methyl- or ethyl-aniline from the commercial product consists in converting it into the Y-nitroso derivative with nitrous acid, followed by reduction of the nitroso compound with tin and hydrochloric acid ... 

Tertiary aliphatic - aromatic amines, unlike those of the aliphatic series, react with nitrous acid with the formation of G-nitroso compounds the nitroso group enters almost exclusively in the para position if available, otherwise in the ortho position. Thus dimethylaniline yields />-nitrosodiniethylaniline ... 

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