Nitrosation is a process of converting organic compounds into

nitroso In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety (chemistry), moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkane ...

derivatives, i.e. compounds containing the R-NO functionality.

''C''-Nitroso compounds

''C''-Nitroso compounds, such as nitrosobenzene, are typically prepared by

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...

of hydroxylamines: :RNHOH + → RNO + H₂O

''S''-Nitroso compounds

''S''-Nitroso compounds ( ''S''-nitrosothiols) are typically prepared by

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapo ...

of a

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

and

nitrous acid Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagent ...

: :RSH + HONO → RSNO + H₂O

''O''-Nitroso compounds

''O''-

Nitroso In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety (chemistry), moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkane ...

compounds are similar to ''S''-nitroso compounds, but are less reactive because the oxygen atom is less

nucleophilic In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

than the sulfur atom. The formation of an alkyl nitrite from an alcohol and nitrous acid is a common example: :ROH + HONO → RONO + H₂O

''N''-Nitrosamines

''N''-

Nitrosamine In organic chemistry, nitrosamines (or more formally ''N''-Nitrosamines) are organic compounds with the chemical structure , where R is usually an alkyl group. They feature a nitroso group () bonded to a deprotonated amine. Most nitrosamines a ...

s, including the carcinogenic variety, arise from the reaction of

nitrite The nitrite ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also ...

sources with amino compounds, which can happen during the curing of meat. Typically this reaction proceeds via the attack of the

nitrosonium The nitrosonium ion is , in which the nitrogen atom is bonded to an oxygen atom with a bond order of 3, and the overall diatomic species bears a positive charge. It can be viewed as nitric oxide with one electron removed. This ion is usually ob ...

electrophile on an amine: :NO₂⁻ + 2 H⁺ → NO⁺ + H₂O :R₂NH + NO⁺ → R₂N-NO + H⁺ Formation of an ''N''-nitrosamine: :The nitrosamine can then lose water through protonation to form diazonium cation, which is a very useful intermediate to form different compounds.

References

External links

Nitrosation of Amines
{{Nitric oxide signaling Organic reactions