Solveeit Logo
Login

Question

Question: Which of the following is not a cumulated diene? A. Hexa-1, 2-diene B. Hexa-2, 3-diene C. Pent...

Which of the following is not a cumulated diene?
A. Hexa-1, 2-diene
B. Hexa-2, 3-diene
C. Penta-2, 3-diene
D. Penta-1, 3-diene

Explanation

Solution

Cumulated diene has two continuous double bonds C=C=CC = C = C structure.

Complete answer:
Given:

Hexa−1, 2−diene→CH2=C=CH−CH2−CH2−CH3 Hexa−2, 3−diene→CH3−CH=C=CH−CH2−CH3 Penta−2, 3−diene→CH3−CH=C=CH−CH3 Penta−1, 3−diene→CH2=CH−CH=CH−CH3  Hexa - 1,{\text{ }}2 - diene \to C{H_2} = C = CH - C{H_2} - C{H_2} - C{H_3} \\\ Hexa - 2,{\text{ }}3 - diene \to C{H_3} - CH = C = CH - C{H_2} - C{H_3} \\\ Penta - 2,{\text{ }}3 - diene \to C{H_3} - CH = C = CH - C{H_3} \\\ Penta - 1,{\text{ }}3 - diene \to C{H_2} = CH - CH = CH - C{H_3} \\\

We know that cumulated diene has two continuous double bonds C=C=CC = C = C structure.
Therefore only penta-1, 3-diene is not a cumulated diene. It does not have continuous double bonds around the carbon atoms.

Hence option ‘C’ is the correct answer.

Note: Cumulated dienes are the two double bonds connected to similar carbon atoms. Cumulated dienes are less stable than the other alkenes. Conjugated dienes are two double bonds separated by a single bond. Non conjugated (isolated) dienes are two double bonds separated by more than one single bond.