Spectrometric and theoretical evidences for the occurrence of tautomeric structures of selected ketones

Mass spectral and theoretical studies on the tautomerism of selected thioesters

“…Evidently, among organic compounds families, esters are rather unique in regard to their mass spectra and the use of mass spectrometry data to study their tautomeric equilibria (equation 5), methodology that has been very useful to predict tautomerism occurrence for other compounds families [28][29][30][31][32][33][34][35][36] . For esters, the spectral interferences have to be considered carefully for the comparison among family members.…”

Tautomerism of lactones and related compounds. Mass spectrometric data and theoretical calculations

“…30 In our laboratory studies on the tautomeric equilibrium of diverse families of compounds have been carried out and, so far, mass spectrometry and semiempirical calculations (AM1) have proved to constitute powerful tools for prediction of fast equilibrium occurrence. [31][32][33][34][35][36][37] This methodology approach has been used in this work to study the tautomerism of selected lactones and esters and their thio analogues.…”

Spectrometric Studies and Semi-Empirical Calculations of Some Thiomorpholides

“…In this sense, diverse families of compounds have been studied [10][11][12][13][14][15][16][17] and adequate support has been found by reporting that negligible influence on the tautomeric equilibrium position occurs after ionization in the ion source of the mass selective detector used to generate the experimental data.…”

“…For this reason and because of the high similarity between MS (commercial databases) and GC/MS spectra, analytical separation has not been considered critical for the present work. Analo- The results obtained by GC/MS when correlated with those from semi-empirical molecular orbital calculations for amides, ureas, hydantoins, isoquinolinones, ketones, diketones, lactones, demonstrate that mass spectrometry constitute an adequate tool for predicting tautomeric equilibrium shifts within a family of organic compounds [10][11][12][13][14][15][16][17]. As mentioned above, tautomerism for some thiomorpholides is studied by resorting to gas chromatography -mass spectrometry and semi-empirical calculations.…”

“…As it has been demonstrated in the case of keto-enol tautomerism of a series of 1-and 3-substituted acetylacetones [9] and a variety of carbonylic and thiocarbonilic compounds [10][11][12][13][14][15][16][17], there is no significant interconversion of the tautomeric forms in the gas phase following electron impact ionization in the mass spectrometer (molecular ions, M + .…”