Studies on the oxidation of 1, 3-dithiane and 5, 5-disubstituted analogues including X-ray crystal structure, equilibration studies and pK a measurements on selected oxides

Dependence of Stereoelectronic and Charge Effects on pKa Values of 1,3‐Dithiane‐Derived Sulfides, Sulfoxides, and Sulfones: An Experimental and Computational Investigation

“…The higher acidity of sulfone 4 is not controlled by stereoelectronic effects, which are again quite similar (72.4 kJ/mol) to those for 5 and 6 , but is ruled by charge effects because the charge of the sulfur of the sulfone is significantly higher than that of the charges of the sulfur atoms in a bis‐sulfoxide (Table 1). The measured p K a values of 5 and 6 are in good agreement with those published for the conformationally flexible compounds 25 (p K a = 22.0, Table 3) and 26 (24.9) 7. Whereas 25 can be expected to be in a conformation (and have a stability) that is similar to that of 5 (cf.…”

Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

“…This result is in agreement with previous work where it has been reported that oxidation of 1,3-dithiane to the monosulfoxide occurred rapidly but that oxidation to the sulfone competed with oxidation of the second sulfide to the disulfoxide. 38 The structure of 8 was confirmed by 1 HNMR (after reduction with phenylhydrazine), IR, and MS. Biradical 8 was soluble in DMSO, in 60:40 DMSO/H 2 0 (20 mM), and in water (5 mM).…”

“…Sulfones are not known to be especially good at imparting water solubility although they do contain polar sulfur-oxygen bonds. 38 However, the lack of water solubility observed for 4 may also be a consequence of the structural rigidity. Sulfoxides contain sulfur-oxygen bonds that are significantly more polarized than those in sulfones, and in addition they offer more opportunity for the solvent to interact with the electropositive sulfur atom as compared to more sterically shielded sulfones.…”

Conformational Energies in Organic Six-Membered Cyclic Sulfoxides

“…11 The oxidation of 1,3-dithiane with different oxidizing agents results in cis-and trans-1,3-di-sulfoxides. 30 The S C S bond angle in 6aa is expanded relative to other isomers shown in Table III. This expansion of the bond angle is caused by a repulsion between the two negatively polarized axial oxygens.…”