Good yields of
R—I may be obtained by heating alcohols with sodium or potassium
iodide in 95% orthophosphoric acid The order of reactivity of alcohols
with a given haloacid is 3°>2°>1° Phosphorus tribromide and triiodide
are usually generated in situ (produced in the reaction mixture) by the
reaction of red phosphorus with bromine and iodine respectively 6