Metabolic activation of the<unk>  NDMA, involving its conversion to an alkylating agent The organic chemistry of<unk> s is well developed with regard to their syntheses, their structures, and their reactions. They usually are produced by the reaction of nitrous acid (HNO2) and secondary amines. :HONO + R2NH → R2N-NO + H2O The nitrous acid usually arises from protonation of a nitrite. This synthesis method is relevant to the generation of<unk> s under some biological conditions. With regards to structure, the C2N2O core of<unk> s is planar, as established by X-ray crystallography. The N-N and N-O distances are 132 and 126 pm, respectively in dimethylnitrosamine, one of the simplest members of a large class of N-nitrosamines<unk> s are not directly carcinogenic. Metabolic activation is required to convert them to the alkylating agents that modify bases in DNA, inducing mutations. The specific alkylating agents vary with the<unk> , but all are proposed to feature alkyldiazonium centers.
Nitrosamine
Carbon monoxide
Nitrous oxide 
Nicosan
Benzene
Vinyl chloride
Nitrobenzene
N-Nitrosodimethylamine