Aryl Fluoroalkyl Sulfoxides: Optical Stability and pKa Measurement. Issue 36 (3rd August 2021)

• Record Type: Journal Article
• Authors: Messara, Amélia; Vanthuyne, Nicolas; Diter, Patrick; Elhabiri, Mourad; Panossian, Armen; Hanquet, Gilles; Magnier, Emmanuel; Leroux, Frédéric R.
• Is Part Of: European journal of organic chemistry. Issue 36(2021)
• Page Start: 5019
• Page End: 5026
• Publication Date: 2021-08-03
• Subjects: Absorption -- Acidity -- Enantiomerization -- Fluorine -- Sulfoxide; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202100816
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: The enantiomeric separation of aryl trifluoromethyl and difluoromethyl sulfoxides was realized via chiral chromatography. The configurational stability of each set of enantiomers was then studied by thermal enantiomerization. The Δ G ≠ values obtained cover a range of 38.2–41.0 kcal mol −1 at 214 °C, thus demonstrating their optical stability at room temperature. However, a shorter half‐life time has been observed for difluoromethyl sulfoxides. Furthermore, the acidities of six aryl difluoromethyl sulfoxides were determined in DMSO by an overlapping indicator method using UV‐visible spectrophotometric titrations. The p Ka values fall in range of 20.3–22.5 and differ by about 10 log units compared to non‐fluorinated analogues. Abstract : Key properties of chiral aryl fluoroalkyl sulfoxides with strong synthetic potential were studied. After resolution by enantioselective chromatography, their optical stability was investigated by thermal enantiomerization via enantioselective chromatography. Their Δ G values range from 38.2 to 41.0 kcal mol −1 at 214 °C. In addition, the p Ka values of six aryl difluoromethyl sulfoxides were determined via indirect UV‐visible spectrophotometric titrations in DMSO and are in the range of 20.3–22.5.