Chapter 10: Addition Reactions of Conjugated Dienes

Diene

Molecule with 2 double bonds

Conjugated double bonds

1 single bond between double bonds

Addition reagents for conjugated dienes

HBr, Br2, Cl2

Kinetic product

Less stable product but faster reaction due to stronger carbocation

Favored at LOW TEMPS

Thermodynamic product

More stable product, but formed via weaker carbocation

Steps of conjugated diene addition reactions:

1. Decide which double bond reacts based on which has higher degrees (1, 2, 3)

2. Draw strongest carbocation, then it’s resonance structure

3. Nucleophile attacks charge and for each so assign products based on substitution

Diels-Alder reaction

Formation of cyclohexene ring from diene and dienophile

Dienophile

Alkene with electron withdrawing group (EN atom, pi bonds)

Cyclic diene reaction

2 isomers, endo and exo, are made

Endothermic

Predominating product, substitutent is down

Exothermic

Substituent is up