The observation that di-(8-chloroethyl) ether may be converted into di-(,% chloroethyl) sulfate in high yields by the action of sulfur trioxide'led us to examine the behavior of dioxane toward this reagent. The addition of sulfur trioxide to pure dioxane at ordinary temperatures produces considerable charring bit if the dioxane is first dissolved in an inert solvent such as carbon tetrachloride or ethylene chloride there results an addition product ...