P-Nitroso derivatives

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). ... 

Nitrosamines, 1074, 1076 Nitrosobenzene, 629, 630 Nitroso compounds, table of, 1085 p-Nitroso derivatives, 660 N-Nitrosodiethylamine, 426 N-Nitrosodimethylamine, 426 p-Nitrosodimetlivlaniline, 562,573 N-Nitrosoethylaniline, 570 N-Nitrosomethylaniline, 562. 563, 570 p-Nitroso-N-methylanOine, 563, 574 Nitrosomethylurea. 968, 969 a-Nitroso-(3-naphthol, 958 (3-Nitrostyrene, 709, 717 a(3-Nonenoic acid, 405, 468 -Nonoic acid. 487... 

The nitrosonium ion (NO), generated in situ from sodium nitrite in the presence of hydrochloric acid at 0-5 °C, is also a weak electrophile and with tertiary amines, e.g. AyV-dimethylaniline, ring substitution occurs leading to the p-nitroso derivative (Expt 6.62). 

Similarly the nitration of dimethylaniline yields p- nitroso derivative, which undergoes similar reactions, to form HCN. 

C-Nitroso compounds. As an alternative to diazo coupling and reduction, a phenol is often converted into the o- or p-nitroso derivative and this is reduced, as exemplified by Sherman and Taylor s synthesis of diaminouracil." The rose red... 

Purely aromatic or purely aliphatic tertiary amines and quaternary ammonium salts do not react with nitrous acid, but mixed aromatic-aliphatic amines of the dimethylaniline type form green or yellow p-nitroso derivatives (Figure 3.5.4) when treated with nitrous acid. This reaction has also been used for the determination of nitrites. 

Nitroso-con unds. (a) C-Nitroso-compoimds. These are generally found as nitrosophenols or p-nitroso-derivatives of dialkylanilines. Their colour is usually green (p-nitrosodialkylani-lines) or yellow (salts of p-nitrosodiaUcylanilines, nitrosophenols). 

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