Replacement of oxygen by sulfur in small organic molecules. 3. Theoretical studies on the tautomeric equilibria of the 2OH and 4OH-substituted oxazole and thiazole and the 3OH and 4OH-substituted isoxazole and isothiazole in the isolated state and in solution was written by Nagy, Peter I.. And the article was included in International Journal of Molecular Sciences in 2016.Product Details of 1003-07-2 This article mentions the following:
This follow-up paper completes the author’s investigations to explore the in-solution structural preferences and relative free energies of all OH-substituted oxazole, thiazole, isoxazole, and isothiazole systems. The polarizable continuum dielec. solvent method calculations in the integral-equation formalism (IEF-PCM) were performed at the DFT/B97D/aug-cc-pv(q+(d))z level for the stable neutral tautomers with geometries optimized in dichloromethane and aqueous solution With the exception of the predictions for the predominant tautomers of the 3OH isoxazole and isothiazole, the results of the IEF-PCM calculations for identifying the most stable tautomer of the given species in the two selected solvents agreed with those from exptl. investigations. The calculations predict that the hydroxy proton, with the exception for the 4OH isoxazole and 4OH isothiazole, moves preferentially to the ring nitrogen or to a ring carbon atom in parallel with the development of a C=O group. The remaining, low-fraction OH tautomers will not be observable in the equilibrium compositions Relative solvation free energies obtained by the free energy perturbation method implemented in Monte Carlo simulations are in moderate accord with the IEF-PCM results, but consideration of the ΔGsolv/MC values in calculating ΔGstot maintains the tautomeric preferences. It was revealed from the Monte Carlo solution structure analyses that the S atom is not a hydrogen-bond acceptor in any OH-substituted thiazole or isothiazole, and the OH-substituted isoxazole and oxazole ring oxygens may act as a weak hydrogen-bond acceptor at most. The mols. form 1.0-3.4 solute-water hydrogen bonds in generally unexplored numbers at some specific solute sites. Nonetheless, hydrogen-bond formation is favorable with the NH, C=O and OH groups. In the experiment, the researchers used many compounds, for example, Isothiazol-3(2H)-one (cas: 1003-07-2Product Details of 1003-07-2).
Isothiazol-3(2H)-one (cas: 1003-07-2) belongs to isothiazole derivatives. The chemistry of isothiazoles is being intensively developed, which is evidenced by the wide range of selective transformations involving the isothiazole heterocycle and the high biological activity of its derivatives that can be used as effective new drugs and plant protection chemicals. In general, isothiazole undergoes nitration in the presence of HNO3, sulfuric acid, and sulfonation by using sulfuric acid under thermal conditions to generate corresponding 4-nitro- and 4-sulfonic acid derivatives, respectively.Product Details of 1003-07-2
Referemce:
Isothiazole – Wikipedia,
Isothiazole – ScienceDirect.com