Question

Among the above given pair, identify the one which gives higher heat of hydrogenation?

• A. I
• B. II
• C. Both are equal
• D. Cannot be determined

Answer 1

The correct option is A I

In compound (I), the double bonds are not conjugated.
In compound (II), the double bonds are conjugated. This results in delocalization of the electron density, which imparts greater stability to conjugated diene.
More stable conjugated dienes have lower heats of hydrogenation than less stable non conjugated dienes.
Hence, compound (I) has higher heat of hydrogenation than non conjugated diene.