Addition of Hydrogen Halide to an Alkyne

 Reactivity order of hydrogen halides: HI > HB r> HCl > HF.

Follows Markovnikov’s rule:

• Hydrogen adds to the carbon with the greatest number of hydrogens, the halogen adds to the carbon with fewest hydrogens.
• Protination occurs on the more stable carbocation. With the addition of HX, haloalkenes form.
• With the addition of excess HX, you get anti addition forming a geminal dihaloalkane.