Nitroso, amines

The Reaction has the following limitations (i) a compound that can liberate nitrous acid in acid solution is required (e.g., a metallic nitrite or a nitroso-amine, p. 204). (2) Nitrophenols and />-substituted phenols do not give the test. (3) Among the dihydroxyphenols. only resorcinol gives a satisfactory positive test. 

Nitrosation of amines is best illustrated by examining what happens when a sec ondary amine reacts with nitrous acid The amine acts as a nucleophile attacking the nitrogen of nitrosyl cation The intermediate that is formed m the first step loses a pro ton to give an N nitroso amine as the isolated product... 

A/-Nitroso amines are stabilized by electron delocalization Write tn tw most stable resonance forms of A/-nitrosodimethylamine... 

N Nitroso amines are more often called nitrosamines and because many of them are potent carcinogens they have been the object of much investigation We encounter nitrosamines m the environment on a daily basis A few of these all of which are known carcinogens are... 

Secondary alkylamines and secondary arylamines y e d N nitroso amines... 

Nitrosation (Section 22 15) The reaction of a substance usu ally an amine with nitrous acid Pnmary amines yield dia zonium 10ns secondary amines yield N nitroso amines Tertiary aromatic amines undergo nitrosation of their aro matic ring... 

N Nitroso amine (Section 22 15) A compound of the type R2N—N=0 R may be alkyl or aryl groups which may be the same or different N Nitroso amines are formed by ni trosation of secondary amines... 

There is no reference to the formation of the ortho nitroso amine in the benzene series, indeed the formation and characterisation of ortho nitroso amines from any reaction has only been reported once or twice79. When the para position is blocked by a substituent, de-nitrosation so the secondary amine can occur80 a certain amount (which depends on the conditions) of denitrosation occurs also, concurrently with the rearrangement81, so that N-nitroso-N-methylaniline (XLVII) yields N-methylaniline (XLVIII) as well as the rearrangement product p-nitroso-N-methylaniline XLIX, viz. 

It is worth noting, however, that the prototropic equilibrium between the A-nitroso amine (30) and the diazenol (31) has been determined semiquantitatively for the analogous diazotization of an aliphatic amine. Fishbein and coworkers100 determined an upper limit for the nitrosoamine equilibrium concentration (<1.5%). 

However, the chemical shift for a o-bound M-aryl bond appears at high frequency, often between 130 and 180 ppm. Both the cydometallated nitroso-amine compound 65 [63-65] and the Pd(ii)(Duphos) complex 66 (an intermediate in the enantioselective hydroarylation of norbornene) [66] represent typical examples. 

Few examples of the preparation of hydrazines or hydroxylamines on insoluble supports have been reported (Table 10.17). Hydrazines have been prepared by the reduction of aromatic diazonium salts or /V-nitroso amines (prepared from secondary amines by treatment with tert-butyl nitrite [340]), and by the N-amination of support-bound amines (Entry 3, Table 10.17). The direct reduction of hydrazones with borane to yield hydrazines on solid phase has not been reported, and appears to be difficult because of the ease with which the N-N bond of hydrazines is cleaved by reducing agents [340]. 

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