Research Article Open Access

Intrahydrogen Bonding and Transition States Between Enol and Enethiol Tautomers in β-Thioxoketones

Bahjat A. Saeed1, Rita S. Elias1 and Ebraheem Abdu Musad2
  • 1 ,
  • 2 , Afganistan
American Journal of Applied Sciences
Volume 8 No. 8, 2011, 762-765

DOI: https://doi.org/10.3844/ajassp.2011.762.765

Submitted On: 15 May 2011 Published On: 18 July 2011

How to Cite: Saeed, B. A., Elias, R. S. & Musad, E. A. (2011). Intrahydrogen Bonding and Transition States Between Enol and Enethiol Tautomers in β-Thioxoketones. American Journal of Applied Sciences, 8(8), 762-765. https://doi.org/10.3844/ajassp.2011.762.765

Abstract

Problem statement: Hydrogen bonding is one of the most important concepts in chemistry because it is crucial to understand many different interactions both in gas phase and in condensed media. A particular subset is presented by the intramolecular hydrogen bonds where two ends of the same molecule interact, resulting in a ringlike structure. Approach: The study involved theoretical investigation of proton transfer and transition states in β-thioxoketones. Both structures of the enol and enethiol tautomers of β-thioxoketones were geometrically optimized then the transition states were obtained. The calculations were done at the B3LYP hybrid and 6-31G(d,p), 6-31+G(d,p), 6- 31++G(d,p), 6-311G(d,p), 6-311+G(d,p) and 6-311++G(d,p) basis sets. Results: The calculated energies of the enethiol tautomer are higher than those of the enol tautomer for all the thioxoketones studied in this work. The S...O distances are in the order: enethiol > enol > transition state in addition the hydrogen bonding in the enol tautomer is stronger than that in the enethiol tautomer. Conclusion: The interconversion within the tautomeric mixture in these compounds is preferable in the enethiol → enol direction.

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Keywords

  • β-thioxoketones
  • density functional theory
  • intrahydrogen bonding
  • reaction barrier
  • Transition State (TS)
  • tautomeric mixture
  • basis sets
  • enethiol
  • ringlike structure
  • isolatedmolecule conditions
  • harmonic analyses