Click the reaction arrows and structures in the sequence to view the 3D models and animations respectively
Sulfoxides next to electron-withdrawing groups are unstable on heating and so can decompose by an elimination process forming rather unstable phenylsulfenic acid (PhSOH).
Me is used in place of Ph in the animation for simplicity.
B. M. Trost, T. N. Salzmann and K. Hiroi, J. Am. Chem. Soc., 1976, 98, 4887–4902.