TITLE:
Thiosemicarbazones Synthesized from Acetophenones: Tautomerism, Spectrometric Data, Reactivity and Theoretical Calculations
AUTHORS:
Belén Gastaca, Hernán Rubén Sánchez, Fiorella Menestrina, Maricel Caputo, María de las Mercedes Schiavoni, Jorge Javier Pedro Furlong
KEYWORDS:
Thiosemicarbazones, Tautomerism, MS, NMR, Theoretical Calculations
JOURNAL NAME:
International Journal of Analytical Mass Spectrometry and Chromatography,
Vol.7 No.2,
June
28,
2019
ABSTRACT: Tautomeric forms of Thiosemicarbazones have been investigated by spectrometric methods, their chemical reactivity and theoretical calculations of the relative tautomers stabilities. The mass spectral fragmentation of thiosemicarbazones synthesized from acetophenones has been studied by CG/MS. The analysis of the corresponding spectra shows not only the regular fragmentation mechanisms but homolytic ruptures from even-electron species. 1H NMR spectra exhibit signals for the most intense open thioketo tautomeric structure, although when using TFA a ring structure is observed in the corresponding tautomeric equilibrium. Density Functional Theory calculations (DFT) also provide evidence to support the experimental observations by GC-MS and 1H NMR. Methylation reactions give support to the occurrence of the thioenol tautomeric form which would be the second most abundant according to the Density Functional Theoretical calculations.