The mass spectra of some aliphatic and alicyclic sulphoxides and sulphones

Abstract

Abstract Characteristic fragmentation processes of aliphatic sulphoxides and sulphones such as loss of hydroxyl, ‘alkene’ and/or ‘alkenyl’ are associated with hydrogen migrations to oxygen. A study of the mass spectra of di‐ n ‐butyl sulphoxide and sulphone, the saturated five‐, six‐ and seven‐membered ring sulphoxides and sulphones and their site‐specifically deuterated analogues shows that these hydrogen migrations are nonspecific. Apparently steric factors play an important role in determining the relative contributions of initial hydrogen transfer from the various positions. The sites of abstraction probably determine the extent of competition between consecutive or concerted loss of hydroxyl, carbon‐sulphur fission or other processes (e.g. McLafferty rearrangement). Apart from the McLafferty rearrangement only the loss of hydroxyl from sulphones shows a strong dependence on the site of initial hydrogen abstraction: γ‐hydrogen is lost preferentially, yielding a cyclized [M  OH] ion.