Aryl Fluoroalkyl Sulfoxides: Optical Stability and pKa Measurement

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 Delta G(not equal) values obtained cover a range of 38.2-41.0 kcal mol(-1) at 214 degrees 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 pK(a) values fall in range of 20.3-22.5 and differ by about 10 log units compared to non-fluorinated analogues.

Automated summary

The study achieved enantiomeric separation of aryl trifluoromethyl and difluoromethyl sulfoxides using chiral chromatography, followed by investigating the configurational stability of each set of enantiomers. The results showed good optical stability of these compounds at room temperature, with a shorter half-life observed for difluoromethyl sulfoxides. Additionally, the acidities of six aryl difluoromethyl sulfoxides were determined and showed significant differences compared to non-fluorinated analogues.