Involvement of the enol tautomers in the nitrosation of ketones

A further study of acetylacetone nitrosation

“…In 1987, the Williams' research group carried out a detailed kinetic study of the nitrosation of ketones. [4][5][6][7] The first study on the topic that includes the nitrosation of acetone (Ac), ethyl-methylketone (EMK), acetylacetone (AcAc), and 1,3-dichloroacetone was performed under conditions of [ketone] ≫ [HNO 2 ], with [HNO 2 ] > 2 mM in order to be able to follow the reaction by UV-vis spectroscopy at λ = 385 nm where nitrous acid, the limiting reagent, absorbs. The nitrosation of simple ketones, such as Ac or EMK, in the presence of nucleophiles (X − ), e.g.…”

Determination of keto–enol equilibrium constants and the kinetic study of the nitrosation reaction of β-dicarbonyl compounds

“…1 Detailed studies of the mechanism of this reaction in water have been carried out recently by Williams and co-workers. [2][3][4] The reaction, analogous to other electrophilic substitutions, involves enolization of the ketone (or, more generally, tautomerisation), followed by electrophilic nitrosation of the enol, important intermediates in many reactions. In some cases there is evidence of the involvement of enolates or carbanions 5 as the effective substrates, the latter being the only route detected for malononitrile both in acid 6 and in basic 7 conditions.…”

A new method for the nitrosation of 1,3-diketones applied to 3-ethyl- and 3-methyl pentane-2,4-dione

“…[1][2][3] The nitrosation of b-diketones has been the subject of several studies. [4][5][6][7][8] The time course of the reaction can be followed by UV-vis spectrophotometry monitoring the absorbance decrease due to either the nitrous acid or the enol of the b-diketone, depending on which of them was the limiting reagent. In aqueous acid medium, the nitrous acid has a structured absorption band within the 350-400 nm region, whereas the enol of b-diketone normally absorbs at a lower wavelength, 270-300 nm.…”