1,2-Dibromoethane → 2,2,3,3,5,6-Hexafluoro-2,3-dihydro-1,4-dioxine

Participants

Reaction Steps

A suspension of 39.2 g (0.60 mol) of zinc dust in 300 mL of dry DMF was stirred under N2 while 5 mL of 1,2-dibromoethane was added. Then a small portion of 74.0 g (0.28 mol) of dichloride 5 was added, and the mixture was stirred and heated. When an exothermic reaction started (about 75° C.), the rest of 5 was added dropwise at a rate sufficient to maintain 110°-120° C. in the pot while product was collected in a -80° C. trap. When the addition was completed, the mixture was heated to reflux to drive out the last of the product. Fractionation of the crude volatile product gave 24.5 g (45%) of pure perfluoro-2,3-dihydro-1,4-dioxin (7), bp 18°-19.5° C. IR (gas): 1845 cm-1 (w, C=C).

Provenance & Evidence