Question

Pick out the correct statements from the following and choose the correct answer from the codes given below
1. Hexa-$1, 5$-diene is a conjugated diene
2. Prop-$1, 2$-diene is conjugated diene
3. Hexa-$1, 3$-diene is a conjugated diene
4. Buta-$1, 3$-diene is an isolated diene
5. Prop-$1, 2$-diene is a cumulative diene

• A. 1, 2
• B. 2, 3
• C. 4, 5
• D. 2, 5
• E. 3, 5

Answer 1

Answer: (E)

In conjugated diene alternate single and double bonds are present while in cumulative diene, double bonds are present at adjacent positions.
1. $ \underset{hexa-1,\text{ }5-diene}{\mathop{{{H}_{2}}\overset{1}{\mathop{C}}\,=\overset{2}{\mathop{C}}\,H\overset{3}{\mathop{C}}\,{{H}_{2}}\overset{4}{\mathop{C}}\,{{H}_{2}}\overset{5}{\mathop{C}}\,H=\overset{6}{\mathop{C}}\,{{H}_{2}}}}\, $
$ \Rightarrow $ it is an isolated diene.
2. $ \underset{prop-1,\text{ }2-diene}{\mathop{{{H}_{2}}\overset{1}{\mathop{C}}\,=\overset{2}{\mathop{C}}\,=\overset{3}{\mathop{C}}\,{{H}_{2}}}}\,\Rightarrow $
It is a cumulative diene.
3. $ \underset{hexa-1,\text{ }3-diene}{\mathop{{{H}_{2}}\overset{1}{\mathop{C}}\,=\overset{2}{\mathop{C}}\,H=\overset{3}{\mathop{C}}\,H=\overset{4}{\mathop{C}}\,H\overset{5}{\mathop{C}}\,{{H}_{2}}\overset{6}{\mathop{C}}\,{{H}_{3}}}}\,\Rightarrow $
It is a conjugated diene.
4. $ \underset{buta-1,\text{ }3-diene}{\mathop{{{H}_{2}}\overset{1}{\mathop{C}}\,=\overset{2}{\mathop{C}}\,H-\overset{3}{\mathop{C}}\,H=\overset{4}{\mathop{C}}\,{{H}_{2}}}}\,\Rightarrow $
It is a conjugated diene. 5. Prop-1, 2-diene is a cumulative diene. Hence, statements 3 and 5 are correct.