Question

Oxidative cleavages can help to determine the positions of the triple bonds in alkynes.

(a) An unknown alkyne undergoes oxidative cleavage to give adipic acid and two equivalents of acetic acid. Propose a structure for the alkyne.

(b) An unknown alkyne undergoes oxidative cleavage to give the following triacid plus one equivalent of propionic acid. Propose a structure for the alkyne.

Short answer

Permanent cleavage or ozonolysis is used to determine the position of triple bond alkyne.

The product forming from the ozonolysis of the unknown alkyne is adipic acid, and two equivalent acetic acids reconnect the fragment of the COOH group. The unknown alkyne is deca-2,8-diyne.

Step-by-step solution

Step 1: Structure of unknown alkyne in reaction (a)

Permanent cleavage or ozonolysis is used to determine the position of triple bond alkyne.

The product forming from the ozonolysis of the unknown alkyne is adipic acid, and two equivalent acetic acids reconnect the fragment of the COOH group. The unknown alkyne is deca-2,8-diyne.

Structure of unknown alkyne in reaction (b)

Permanent cleavage or ozonolysis is used to determine the position of triple bond alkyne.

The product forming from the ozonolysis of the unknown alkyne is triacid, and one equivalent propionic acid reconnects the fragment of the COOH group. The unknown alkyne is 3-(but-1-ynyl)cyclodec-1-yne.