Nitroso compounds
Nitroso compounds are a class of organic-chemical compounds with the general structural formula R 1 R 2 R 3 C-N = O. The common feature of all nitroso compounds is the nitroso group -N = O as a functional group.
Nitroso compounds are only stable if no hydrogen is bonded to the carbon that carries the functional NO group, i.e. none of the radicals R 1 to R 3 = H (hydrogen). Otherwise they rearrange into the tautomeric oximes .
Compounds with an NO group on a carbon ( C -nitroso compounds) and those in which this group is bound to a nitrogen atom ( N -nitroso compounds), such as nitrosamines , nitrosamides and nitrosoureas , differ in their chemical and toxicological properties Properties considerably.
C-nitroso compounds can be converted into aliphatic, e.g. B. 2-methyl-2-nitroso-propane , and aromatic nitroso compounds, e.g. B. nitrosobenzene differentiate.
presentation
Aromatic nitroso compounds can be prepared by mild reduction of nitro compounds to win. Electron-rich aromatics can be nitrosylated under mild conditions with sodium nitrite in acetic acid in an electrophilic substitution reaction. The reactive agent is the NO cation.
Aliphatic nitroso compounds are formed by the addition of nitrosyl halides such as nitrosyl chloride to alkenes.
Secondary amines react with nitrous acid by exchanging the amino hydrogen for a nitroso group with formation of water to form the corresponding amide , which is then one of the nitramines .
Properties and use
Nitroso compounds are in equilibrium in solution and in substance with dimeric structures. They can serve as a "spin trap" to detect free radicals .
proof
The qualitative detection of nitroso compounds is carried out with the Tollens sample . Reaction with ammonium chloride and zinc dust in ethanol reduces the nitroso compounds with the formation of hydroxylamine . This reacts with Tollens reagent to form elemental silver .
See also
Individual evidence
- ^ Ulrich Lüning: Organic reactions , Spectrum Academic Publishing House, 3rd edition, 2010, p. 95, ISBN 978-3-8274-2478-5 .
- ^ Ulrich Lüning: Organic reactions , Spectrum Akademischer Verlag, 3rd edition, 2010, p. 158, ISBN 978-3-8274-2478-5 .