Usual secondary amines can form N-nitrosamines with nitrosating agents, e.g., $\ce{KNO2}$, and are therefore forbidden in metalworking fluids.

But can alkylhydroxylamines form N-nitrosamines with nitrosating agents in metalworking fluids?

I assume the basicity of the N-atom in alkylhydroxylamines is lowered by the inductive effect and the mesomeric effect. But is this enough to prevent formation of N-nitrosamines?


Yes they can in acidic solutions according to the abstract of this paper$^{[1]}$:

O-Alkylhydroxylamines react with nitrous acid with a rate law $v = k_2\ce{[R^1NH2^+OR^2][HNO2]}$; the mechanism involves electrophilic nitrosation at the nitrogen atom of the free base. At acid concentrations below $\pu{2M}$-per-chloric acid, hydroxylamine and N-methylhydroxylamine react with nitrous acid by an acid-catalysed mechanism with a rate law $v = k_3\ce{[RNH2^+OH][HNO2]}h_\circ$; this involves initial nitrosation at the oxygen atom of the conjugate acid, followed by migration of the nitrosonium ion to the nitrogen. At higher acidities the O-nitrosation can be reversed, and the migration of the nitrosonium ion becomes the rate-determining stage.


  1. T. D. B. Morgan, G. Stedman, M. N. Hughes, "Kinetics and mechanism of the reaction between nitrous acid and hydroxylamine," J. Chem. Soc. B 1968, 344-349 (DOI: https://doi.org/10.1039/J29680000344).

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