Enol and Enethiol Occurrence for Some Ketones and Thioketones. Mass Spectrometry and Theoretical Calculations

Abstract

Abstract:The mass spectra of ketones can provide valuable information with regards to keto-enol equilibria occurring in the gas phase. Mass spectra of selected ketones and thioketones have been analysed and specific fragmentation assignments have been done to characterised and weigh co-existing keto and enol tautomers. Thioketones are of particular interest due to their tendency to shift the tautomeric equilibrium towards the enethiol form. The predictive value of this methodology is not only supported by the influence of these compound's nature and size of the substituent on these equilibria but also by the good correlation found between the selected fragments abundances ratio and semi-empirical calculation (AM1) of the corresponding heats of tautomerization.

Synthesis of heterocyclic compounds with adamantane-like cage structures consisting of phosphorus, sulfur, and carbon

“…In refluxing solvents, P4S10 dissociates into P2S5 (I) and then, the desired thioacetophenone is formed through forming fourmembered ring II. 3a,8b,11b,11c,17b,17e,18 Because of the thiocarbonyl group tends to turn into a stable C-S bond, 19 the more reactive enthiol form of thioacetophenone immediately reacts with the fragments I or III and the generated IV recombines with I to form 2a. On the other hand, path B is based on the direct reaction of acetophenone with P4S10.…”

Spectrometric Study of the Nitrile-Ketenimine Tautomerism

“…It has been demonstrated, in the case of keto-enol tautomerism of a variety of carbonyl and thiocarbonyl International Journal of Spectroscopy 3 compounds [38][39][40][41][42][43][44][45][46][47][48][49], that there is no significant interconversion of the tautomeric forms in the gas phase following electron impact ionization in the mass spectrometer (molecular ions, M +. , do not seem to undergo unimolecular tautomerization), and, even more surprising, for GC/MS experiments, once the solvent is separated after injection in the injection port of the gas chromatograph, tautomerism mechanisms (intermolecular, unimolecular) would not seem to take place even with no GC separation (under the selected experimental conditions).…”

Solvent effect in keto–enol tautomerism for a polymerizable β-ketonitrile monomer. Spectroscopy and theoretical study

“…Tautomerism in organic chemistry has been extensively studied in condensed and gas phase by spectrometric methods on a wide variety of functional groups, such as carbonilic, nitro and nitrile compounds [1][2][3][4]. Considering that numerous cellular processes occur through tautomeric forms of certain compounds, tautomerism has become an interesting field of study.…”