The Appel reaction converts a alcohol into a halide. Initially, triphenylphosphine reacts with tetrahalomethane to form the so called Appel salt, which transforms the alcohol into the halide.
“Tertiary Phosphane/Tetrachloromethane, a Versatile Reagent for Chlorination, Dehydration, and P-N Linkage” Rolf Appel, Angew. Chem. 1975, 87, 863–874; Angew. Chem. Int. Ed. Engl. 1975, 14, 801–811.