N-Nitrosamides, decomposition

Mechanisms for the thermal and photolytic decomposition of N -nitrosamides are briefly reviewed, and recent results for their decomposition by acidic and basic catalysts are summarised and discussed ... 

N-Nitrosamides are much less stable than the parent N-nitros-amines and they can decompose by either thermal, photolytic or acid and base (nucleophilic) catalysed pathways Thermal decomposition has attracted much attention as a clean method of deamin-... 

The tendency for N-nitrosamides to undergo hydrolysis by a nucleophilic catalysed pathway has been confirmed by studies of N-alkylnitroso acetamides (22) Results summarised in Table I for N -n-butyl-JJ -nitroso acetamide show that its decomposition is also subject to steric constraints (2,6-lutidinestrong nucleophiles (eg. imidazole, thiols) irrespective of their base strength (pK ). Further, the second order dependence on [Imidazole] is more clearly defined for the decomposit-... 

One goal of our current investigation is to show that genetically important cellular constituents can initiate the release of an alkylating agent from the N-nitrosamide. This might explain how highly reactive diazohydroxide metabolites effect the alkylation of nucleic acids within the cell nucleus. Preliminary evidence ( ) summarised in Table II shows that the decomposition of... 

Decomposition studies confirmed that N-nitrosamides are much less stable than volatile N-nitrosamines such as NPYR and NDMA (79). Thermal studies utilizing heating conditions commonly encountered in the cooking of bacon and pork roasts indicated that N nitrosomethylpropionamide (NOMP) was degraded to the extent of 74-97% compared to 3-14% for NPYR and NDMA (Table V). It was tentatively concluded that the major... 

Whereas base-induced decomposition of N-nitrosourethanes has been utilized (9) as a popular method of generating diazoalkanes, only limited investigations on base treatments of nitrosamides have been reported (10). The primary product in the base treatment is assumed, in analogy to better investigate nitrosourethane cases, to be diazo hydroxides V via attack of a base on the carbonyl group as in IV. A diazo hydroxide V has been related to the diazo ester III by a reaction with benzoyl chloride. 

In contrast to a straightforward and predictable decomposition pattern of photolysis with >400 nm light, irradiation of nitrosamides under nitrogen or helium with a Pyrex filter (>280 nm) is complicated by the formation of oxidized products derived from substrate and solvent, as shown in Table I, such as nitrates XXXIII-XXXV and nitro compound XXXVI, at the expense of the yields of C-nitroso compounds (19,20). Subsequently, it is established that secondary photoreactions occur in which the C-nitroso dimer XIX ( max 280-300 nm) is photolysed to give nitrate XXXIII and N-hexylacetamide in a 1 3 ratio (21). The stoichiometry indicates the disproportionation of C-nitroso monomer XVIII to the redox products. The reaction is believed to occur by a primary photodissociation of XVIII to the C-radical and nitric oxide followed by addition of two nitric oxides on XVIII and rearrangement-decomposition as shown below in analogy... 

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