Active hydrogen compounds nitrosation

The nitrosation of aliphatic carbon atoms, particularly of carbon atoms activated by adjacent carbonyl, carboxyl, nitrile, or nitro groups, has been reviewed in great detail [2]. Judging from this review, with few exceptions, nitrosation of active methylene compounds leads to the formation of oximes (unfortunately termed isonitroso compounds in the older literature). The few exceptional cases cited in which true nitroso compounds (or their dimers) were formed involved tertiary carbon atoms in which no hydrogen atoms were available to permit tautomerism to the oxime or involved a reaction which was carried out under neither acidic nor basic conditions. 

In the aliphatic series, nitrosation is mainly used for preparation of oximes,244 which are always obtained instead of the true nitroso compounds unless rearrangement can be avoided by choice of special conditions. In general, the reaction is more successful the more strongly the hydrogen to be replaced is activated by electron-attracting groups. 

---