Problems and exercisesDienes and Polyenes
1. Which dienes are conjugated?
Which of these compounds are conjugated dienes? a) 1,3-pentadiene; b) 1,4-pentadiene; c) 2-methyl-1,3-butadiene (isoprene); d) 1,2-butadiene; e) 1,3-cyclopentadiene.
2. Stability
The heat of hydrogenation of 1,3-pentadiene (−54.1 kcal/mol) is lower than that of 1,4-pentadiene (−60.8 kcal/mol). What does this difference show?
3. Characteristic reactivity
Name three reactions of conjugated dienes that isolated alkenes do not undergo.