Question

The olefin which on ozonolysis gives \[{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{CHO}}\] and \[{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{CHO}}\] is
A) 1-butene
B) 2-butene
C) 1-pentene
D) 2-pentene

Answer 1

Hint: Olefins are organic compounds that are also named alkenes. They are composed of only atoms of hydrogen and carbon and at least one triple or double covalent bond. Some examples are propylene and butenes.

Complete Step by Step Answer:
Let’s understand the ozonolysis reaction first. In this reaction, one ozone molecule is added to an unsaturated compound. When a molecule of ozone is added to an alkene, the formation of an ozonide molecule happens. Later, the cleavage of the molecule of ozonide happens and the formation of carbonyl compounds takes place.

Here, we have to identify the alkene which gives two carbonyl compounds namely propanal (\[{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{CHO}}\]) and ethanal (\[{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{CHO}}\]). As the first aldehyde formed is of three carbon atoms, so, the alkene that gives these two aldehydes has a double bond after the first three carbon atoms. And the alkene has five numbers of carbon atoms. So, the alkene is, 2-pentene whose chemical formula is, \[{\rm{C}}{{\rm{H}}_{\rm{3}}} - {\rm{C}}{{\rm{H}}_2} - {\rm{CH}} = {\rm{CH}} - {\rm{C}}{{\rm{H}}_{\rm{3}}}\] .

The ozonolysis reaction of 2-butene is as follows:
\[{\rm{C}}{{\rm{H}}_{\rm{3}}} - {\rm{C}}{{\rm{H}}_2} - {\rm{CH}} = {\rm{CH}} - {\rm{C}}{{\rm{H}}_{\rm{3}}} \overset{O_3}{\rightarrow} {\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{CHO}} + {\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{CHO}}\]
Therefore, the alkene that gives ethanal and propanal on ozonolysis is 2-butene.
Hence, option D is right.

Note: The use of olefin in many industries is significant. Its use as a raw material in the production of polymers such as plastics, adhesives, rubber, detergent, etc. is very important. It also possesses a water-resistant quality. It does not absorb water and it dries very quickly.