NMR and Mass Spectra of Conformational Isomers of 2-Methylpentane-2,4-Diol Sulfite

From the ester exchange reaction between 2-methylpentane-2.4-diol and dimethyl sulfite, two isomeric cyclic sulfites were isolated in a 3 to 2 ratio. On the basis of IR and NMR data it was concluded that the isomers exist in the rigid chair conformation and the isomerism springs from the pyramidal S?O orientation. An axial S?O is assigned to the liquid isomer (predominant) and an equatorial S?O to the solid compound (minor). The 25 ev mass spectra of the two isomers at room temperature is herein described.