Which of the following best represents the major organic product formed when a terminal alkyne reacts with one equivalent of $H_{\mathrm{Cl}}$ under standard conditions?

Predict the major product(s) of the following reactions:

c. cyclooctyne + 2 HBr

d. *hex-2-yne + 2 HCl

Show how hex-1-yne might be converted to

f. 2,2-dibromohexane.

Using hex-1-ene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)

a. 1,2-dibromohexane

b. hex-1-yne

c. 2,2-dibromohexane

Predict the products of reaction of pent-1-yne with the following reagents.

a. 1 equivalent of HCl

b. 2 equivalents of HCl

c. excess H₂, Ni

Predict the major product(s) of the following reactions:

a. phenylacetylene + 2 HBr

b. hex-1-yne + 2 HCl

Propose a mechanism for the entire reaction of pent-1-yne with 2 moles of HBr. Show why Markovnikov's rule should be observed in both the first and second additions of HBr.

For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (iv) HBr (1 equiv.). If you expect two products, show both.

(c)