A study of the enolization of some alkyl ketones in lyomesophases formed by alkylammonium surfactants

The kinetics of enolization of acetone, 3-pentanone, and 6-undecanone have been studied in lyotropic systems in the isotropic, nematic, and lamellar phases. The data, analysed in terms of spontaneous and acid-catalyzed rate constants, do not show any relevant influence of the physical nature of the phase. Effects are instead observed in relation to the length of the alkyl chains of the ketones and the type of the amphiphilic molecule. 6-undecanone has a surprising effect in stabilizing ordered mesophases.

Studies in organic mass spectrometry. Part 17—Formation of phenol radical ions by rearrangement of the molecular ions of someN-arylthiophenecarboxamides and -benzamides

It has been shown by exact mass measurements and collision-induced dissociation mass-analysed ion kinetic energy spectra that the structure of the m/z 124 ion observed in the mass spectra of N-(4-methoxyphenyl)thiophene-2-carboxamide, N-(4-methoxyphenyl)thiophene-3-carboxamide, N-(4-methoxyphenyl)-5-nitrothiophene-3-carboxamide and N-(4-methoxyphenyl)benzamide is identical with that of the molecular ion of 4-methoxyphenol. This ion becomes abundant in metastable energy window reactions. A probable mechanism for its formation is discussed.

Acidity, hydrogen bonding and complex formation

Ab initioanalysis on metal ion catalysis in the enolization reactions of some acetylheterocycles: kinetics of the enolization reactions of 3-acetyl-5-methylisoxazole, 5-acetyl-3-methylisoxazole and 3(5)-acetylpyrazole

Kinetic data on the enolization reaction of 3-acetyl-5-methylisoxazole, 5-acetyl-3-methylisoxazole, 3(5)-acetylpyrazole and some previously studied acetylheterocycles have been the object of a comprehensive ab initio analysis. Enolization rate constants were measured spectrophotometrically by the halogen trapping technique at 25 °C and ionic strength of 0.3 mol dm−3 in water, in acetate buffers, in dilute hydrochloric acid, in dilute sodium hydroxide and in the presence of some metal ion salts. In the spontaneous (water) and base (acetate) catalysed reactions the ketones investigated are generally more reactive than acetophenone, according to the electron-withdrawing effect of the heterocyc…