Nitroso Phenols

Natriumboranat reduziert Nitroso-benzol in Athanol bei 30° zu Azoxybenzol (75% d.Th.), in Dimethyl-sulfoxid bei 85°zu Azobenzol (78% d.Th.)"1 und4-Nitroso-phenol, in Wasserbei 60°zu 4-Amino-phenol (42%... 

This resulted in an enthalpy of reaction 39 of ca 70 klmol". While this is much larger than what would be predicted for the correction due to nitroso-phenol conjugation and the energies of most hydrogen bonds, the value for the related reaction for p-nitrophenol (equation 40) is the rather comparable 80 klmol". ... 

Davies, R. McWeeny, D. J. Catalytic effect of nitroso-phenols on N-nitrosamine formation. Nature, 1977, 266, 657-658. 

X. ., -(4-nitroso-phenyl)-amin % Umwandlung, bez. auf 4-Nitroso-phenol... 

The structures assigned to some of the nitroso phenols may require reexamination by more modern techniques. 

Benzoquinonemonooxime ond Derivatives Beiizoquinonemonooxime, CgHsNG2 mw 123-11, N 11.38%. This compd exists as ortho and para isomers Benzoquinone-l,2 monooxime [called B en zoc hinon-( 1.2)-monoxim o-Chinon-monoxim or "o-Nitroso-phenol" in Ger], cH- ==-=CH ... 

Silver salt, AgCgH4N02, almost black, but dk blue in transmitted light, fine crysts, expl on heating or on contact with acids Sodium salt, NaCgK4N02, red-grn shiny Ifts, expl on heating Benzoquinone-1,4-monooxime [called Benzo-chinon-(1.4)-monoxim p-Ohinon-monoxim or "p -Nitroso-phenol in Ger],, CH=CH. 

Bromo-l,4-benzoquinone-4-oxime [called 2-Brom -p-chinon-oxim-(4) or 2-Brom-4-nitroso-phenol in Ger], 0 CgH3(Br) N.OH or HO.C6H3(Br).NO-See 4-Nitroso-2-bromophenol under Bromophenol and Derivative s... 

In support of this view the p-amino-phenols themselves readily yield quinones. Also most p-substituted primary amines, e.g., p-diamines, p-alkylamines, such as p-toluidine, sulphanilic acid and its derivatives, behave similarly. In fact, the reaction can be used as a test for p-substi-tuted primary amines. p-Benzoquinone is usually made from aniline for the other p-quinones the p-amino-phenols, which are easily obtained by reduction of the p-nitroso-phenols and of azo-phenols, are employed. These reactions also apply, but not so widely, in the naphthalene series. 

In der Literatur wird die Nitroso-Oxim-Umlagerung im allgemeinen als ein Fall von Keto-Enol-Tautomerie behandelt (64). Ein entsprechendes Tautomerie-Gleichgewicht wurde bisher jedoch nur bei bestimmten aro-matischen Nitrosoverbindungen nachgewiesen, z. B. zwischen j>-Nitroso-phenol und p-Chinon-monoxim (2) ... 

By boiling with KOH it is decomposed into the potassium salt of nitroso phenol and di-methyl amine and the di-methyl amine thus obtained is pure. 

In the case of aniline itself this direct action with nitrous acid does not occur as previously explained. By starting with nitroso phenol, however, the amino group may be introduced in place of the hydroxyl by direct action of ammonia. 

Now this mono-oxime of quinone which must have the above constitution is identical with para-nitroso phenol. 

Quinone Oximes.—The most interesting of the derivatives of quinones are the oximes. As stated in the discussion of the ketone structure for quinones one of the proofs for this constitution is the fact that benzoquinone forms both a mono-and a di-oxime when treated with hydroxyl-amine. The mono- oxime of benzoquinone would have the structure as written below and as given on page 638. Now as previously mentioned, (p. 628), para-nitroso phenol, which is made by the action of nitrous acid upon phenol and the constitution of which is established by other methods of synthesis, (p. 627), proves to be one and the same compound with this mono-oxine of para-benzoquinone, the constitution of which is likewise established by the above reaction of hydroxyl amine upon quinone. This is explained by a rearrangement as shown in the following ,... 

Now the following facts (i) the oxime itself is not known as distinct from para-nitroso phenol, (2) there are known both ethers and esters... 

It may further be obtained by treating the isomeric azoxy-benzene with sulphuric acid [34], and by the action of nitroso-phenol on aniline [33]. 

Tautomeric equilibria have been studied in nitrosophenols. An early study of 4-nitroso-phenol showed an intermolecular tautomerism catalysed by slight traces of water. In dry dioxane both the Af-oxide and the oxime form could be observed . ... 

Certain nitroso phenols and polyhydroxy compounds are exceptions where the exchange takes place under relatively mild conditions and sometimes without the need for a catalyst. For example,/7-nitrosophenol and ammonium salts, when heated on a steam-bath for 0.5 hour, give 50% of /7-nitrosoaniline, 1049.cf.1050 and l-nitroso-2-naphthol and aqueous methylamine solution at 35° give 90% of iV,iV-dimethyl-1 -nitroso-2-naphthylamine.1051 The easier reaction s due to the tautomerism of these phenols with the ketonic isomers, e.g.9 for nitrosophenol ... 

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