[544-16-1] · C4H9NO2 · n-Butyl Nitrite · (MW 103.12)
Physical Data: bp 78 °C; fp -13 °C.
Solubility: sol THF, propanol.
Form Supplied in: commercially available liquid.
Handling, Storage, and Precautions: nitrosation agents should be handled with care since products such as nitrosamines are extremely hazardous.
n-Butyl nitrite has been widely employed as a nitrosation agent, particularly for the preparation of nitrosamines. Examples include the N-dealkylation-N-nitrosation of tertiary aromatic amines (eq 1)1 and the deamination of aziridines (eqs 2 and 3).2
In the first sequence (eq 1) little competing nitration of the aromatic ring was observed. The aziridine deamination occurs by a stereospecific loss of N2O from an intermediate N-nitrosoaziridine. The method can be combined with an aziridine preparation to provide a means of interconverting the (E/Z) isomers of disubstituted alkenes.
Nitrosation of certain carbon electrophiles using butyl nitrite is also feasible, for example the conversion of sulfonamides into the corresponding a-oxime derivatives (eq 4).3
Transition metal catalyzed introduction of oxime (hydroxyimino) functionality into carbonyl compounds and nitriles may also be achieved starting with the corresponding a,b-unsaturated derivatives (eqs 5-7).4 This reaction is thought to proceed via reaction of BuONO with an intermediate cobalt enolate, formed by metal catalyzed conjugate reduction of the starting material by the silane.
The same authors have described a related reaction which transforms simple alkenes into the corresponding nitrosoalkane dimers (eq 8)5 (a radical synthesis of the nitroso alkane dimers is also possible by using t-BuONO).6 This reaction is catalyzed by a number of iron complexes such as Tris(acetylacetonato)iron(III), and proceeds best when nitrogen monoxide, generated by the decomposition of BuONO, is removed from the reaction mixture by bubbling nitrogen gas.
Other uses for butyl nitrite include the nitrosation of amino acid hydrazines,7 used in the Rudinger modification for peptide synthesis, and the substitution of BuONO for other reoxidants in certain palladium-catalyzed reactions.8
Nigel S. Simpkins
University of Nottingham, UK