Question

Which of the following on reductive ozonolysis will give only glyoxal?
(A) Ethylene
(B) Benzene
(C) Toluene
(D) Acetylene

Answer 1

Hint: In order to solve this question, we should first understand the concept of reductive ozonolysis. First of all, ozonolysis refers to the organic chemical reaction where ozone is used to cleave the unsaturation present in alkenes, alkynes and azo compounds.


Complete Step by Step Solution:
Ozonolysis refers to the cleavage of an alkene or alkyne with ozone in order to form organic compounds in which the multiple carbon-carbon bonds are replaced by a double bond attached to oxygen. Ethylene on reductive ozonolysis produces aldehydes. The reductive ozonolysis of benzene yields glyoxal through the formation of benzene triozonide as an intermediate in the chemical reaction. Reductive ozonolysis of toluene which is also called methylbenzene gives us one mole of methylglyoxal and two moles of glyoxal. Acetylene ozonide when hydrolyzed further in the presence of zinc forms glyoxal. Hence, we can say that Benzene and Acetylene on reductive ozonolysis will give glyoxal.
Therefore, the correct answer is option B and D.

Note: Oxidation of alkenes with the help of ozone which is a very reactive allotrope of oxygen can give alcohols, aldehydes, ketones, or carboxylic acids. Alkynes undergo ozonolysis reactions to produce acid anhydrides or diketones. If water is present in the chemical reaction, the acid anhydride undergoes the process of hydrolysis to produce two carboxylic acids. Ozonolysis of elastomers is also referred to as ozone cracking. Trace amounts of ozone gas present in the atmosphere cuts the double bonds present in elastomers. For azo compounds, the ozonolysis reaction produces nitrosamines.