Question

Pick out the correct statement from the following and choose answer from the codes given below:
I. Prop - 1,2 - diene is conjugated diene II. Hexa - 1,3 - diene is conjugated diene
III. Buta - 1, 3 -diene is an isolated diene IV. Prop - 1,2 -diene is a cumulative diene

• A. $II,III$
• B. $IV,V$
• C. $II,IV$
• D. $III,V$

Answer 1

The correct option is C $II,IV$

Conjugated diene - have attenate double single bonds
Cumulative diene - adjacent double bonds
Isolated diene - double bonds far from them each other
1) $H_{2}C=C=C{H}_2$
Prop - 1, 2- diene
as both the double are on some c-atom so it is not conjugated diene, so statement is incorrect.
2) $H_{2}C=HC-HC=CH-C{H}_2-C{H}_3$
Sexa - 1, 3 diene.
As it has alternate double & single bonds, it is a conjugated diene. So the statement is correct.
3) $H_{2}C=HC-HC=C{H}_2$
Bute - 1, 3 diene.
As it has alternative double & single bonds it is a conjugated diene & not isolated diene so this statement is incorrect.
4) $H_{2}C=C=C{H}_2$
Prop - 1, 2 diene
As both double bonds are on same c-atom so it is a cumulative diene. So the statement is correct.
Option C is correct.