The positions of triple bonds in alkynes can be determined through oxidative cleavage. An unknown alkyne gives malonic acid and two equivalents of carbon dioxide, as shown below. Propose the structure of this alkyne.

Using cyclononyne as the starting molecule, propose a method to synthesize cyclononane-1,2-dione.

Predict the product(s) obtained when 2-methylnon-4-yne reacts with the following reagents:

(i) KMnO₄, H₂O, neutral

(ii) KMnO₄, KOH, H₂O, heat, then H⁺, H₂O

An unknown compound X absorbs 5 equivalents of hydrogen to give n-butylcyclopentane when it is treated with hydrogen gas in the presence of a platinum catalyst. The following products are obtained when X is treated with an excess of ozone, followed by dimethyl sulfide and water.

Propose a structure for the unknown compound X. Is there any uncertainty in the structure that you proposed?

Determine the identity of products obtained in the reaction of but-1-yne with each of the reagents shown below.
(i) dilute, cold solution of KMnO₄
(ii) concentrated warm solution of KMnO₄ and NaOH, then HCl
(iii) Na in liquid NH₃