Diethylaminosulfur trifluoride

Diethylaminosulfur trifluoride (DAST) is a reagent used in organic chemistry for a variety of fluorination reactions. In particular, it will convert alcohols to the corresponding alkyl fluorides. DAST is used in preference to the more classical fluorinating reagent sulfur tetrafluoride.

DAST is prepared by the reaction of diethylaminotrimethylsilane and sulfur tetrafluoride:
 * Et2NSiMe3 + SF4 → Et2NSF3 +  Me3SiF