Determine the alkyne and any other reactant that are needed to produce the given molecule.

Draw a mechanism for the reaction of 1 mol of 1-propyne with 2 moles of HBr. The mechanism should explain the Markovnikov regioselectivity of the reaction.

The addition reaction of HX to internal alkynes is anti addition as shown below:

Two chemistry students have a conflicting assessment on whether or not anti-addition would occur on terminal alkynes. Propose a mechanism that could help settle this disagreement.

Predict the major product/s of the reaction of CH₃CH₂CH₂C☰CCH₂CH₂CH₂CH₃ with excess HBr.

Draw the major product(s).

(i) cycloheptyne + 2 HBr

(ii) pent-2-yne + 2 HCl