Analysis of Proton NMR of s-Trioxane Dissolved in a Nematic Solvent

The proton NMR spectrum of s-trioxane dissolved in the nematic mesophase of p,p′-di-n-hexyloxyazoxybenzene has been obtained at 80°C. Computer analysis of this spectrum indicates that s-trioxane exists predominantly in the ``chair'' conformation. This analysis also indicates that each methylene group is tilted by about 3°. That is, the OCO plane does not bisect the HCH angle. This tilt is in the direction which increases the distance between the axial protons. In addition according to this analysis, the indirect 13C–H spin—spin coupling constant is positive.