text: Bougalt's report of iodolactonization represented the first example of a reliable lactonization that could be used in many different systems. Bromolactonization was actually developed in the twenty years prior to Bougalt’s publication of iodolactonization. However, bromolactonization is much less commonly used because the simple electrophilic addition of bromine to an alkene, seen below, can compete with the bromolactonization reaction and reduce the yield of the desired lactone.
  Chlorolactonization methods first appeared in the 1950s but are even less commonly employed than bromolactonization. The use of elemental chlorine is procedurally difficult because it is a gas at room temperature, and the electrophilic addition product can be rapidly produced as in bromolactonization.