Fluorous Solvents for Slow Chlorination and Bromination of Alcohols

By constructing a fluorous liquid membrane between two organic phases, one can mediate the mixing of reagents between the phases. Curran [1] showed that alcohols could be converted to chlorides by the action of thionyl chloride through the fluorous phase. Most of Curran’s examples were alcohols incapable of rearrangement or elimination. In a discovery-based experiment, a sophomore organic chemistry class and a chemical technology class examined this reaction using a diverse set of alcohols. The products were analyzed by GC/MS, and the product ratios could be related to the competition between substitution, elimination, and rearrangement. Similar conversions of alcohols to bromides using SOBr2 and PBr3 were also undertaken. The experiment provided an introduction to fluorous chemistry and allowed students to explore the relationship between reaction mechanisms.