Alkyne Hydrohalogenation Practice Problems

What are the products that would be formed when the following alkyne reacts with HBr (1 equiv.)?

Draw the product(s) that would be produced from the treatment of the following alkyne with HCl (2 equiv.).

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.

Write products for the following alkyne hydrohalogenation reactions:

a. ethynylcyclohexane + 2 HCl
b. cyclooctyne + 2 HBr

Predict the alkyne and reactants needed to produce the following haloalkene.

Draw the product of the addition of one equivalent of the reagent to the molecule shown below.

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 products of each of the reactions between 3-heptyne and the reagents below.

i. HCl (1 mol)

ii. HCl (2 mol)

Draw the major product(s).

(i) cycloheptyne + 2 HBr

(ii) pent-2-yne + 2 HCl

Demonstrate how pent-1-yne could be transformed into 2,2-dibromopentane.

Illustrate how the compounds can be synthesized using pent-1-ene as a starting material. The other synthesized compounds can be used as a starting material for some of the compounds.

(a) 1,2-dibromopentane

(b) pent-1-yne

(c) 2,2-dibromopentane

Determine the identity of products obtained in the reaction of but-1-yne with each of the reagents shown below.
(i) HBr (1 equivalent)
(ii) HBr (2 equivalents)
(iii) H₂ (excess), Pt catalyst