Question

Question: Draw the products formed when each alkyne is treated with O₃ followed by H₂O .

a.

b.

c.

Short answer

Answer

a.

b. A biphenyl compound upon ozonolysis gives the same compound, that is

c.

Step-by-step solution

Terminal and internal alkyne

Alkynes that reside in the middle of the C-C chain are known as internal alkynes and those that reside in any of the ends of the chain are known as terminal alkynes.

Examples are given below:

Internal Alkyne

Terminal alkyne

Oxidative cleavage of alkynes

Alkynes undergo oxidative cleavage when treated with ozone. It leads to cleavage of both sigma and pi-bonds of the alkyne and produces carboxylic acid and carbon dioxide (in case of terminal alkyne).The general reaction scheme is given below:

Oxidative cleavage of the terminal and internal alkyne

Determination of products

a.

Ozonolysis of the internal alkyne gives two carboxylic acid groups

b.

The biphenyl compound reacts with ozone to form 2 moles of benzoic acid

c.

The compound is composed of a terminal as well as an internal alkyne