O-
Nitroso compounds are similar to S-nitroso compounds, but are less reactive because the oxygen atom is less
nucleophilic than the sulfur atom. The formation of an alkyl nitrite from an alcohol and nitrous acid is a common example:
The nitrosamine can then lose water through protonation to form
diazonium cation, which is a very useful intermediate to form different compounds.
References
^Wang, P. G.; Xian, M.; Tang, X.; Wu, X.; Wen, Z.; Cai, T.; Janczuk, A. J. (2002). "Nitric Oxide Donors: Chemical Activities and Biological Applications". Chemical Reviews. 102 (4): 1091–1134.
doi:
10.1021/cr000040l.
PMID11942788.