Chapter 10: Conjugation in Alkadienes and Allylic Systems

Preparation of Conjugated Dienes

• Dienes can be prepared by elimination reactions (review) of unsaturated alcohols and alkyl halides.
• The outcome of eliminations typically favours the more stable product.
• Since conjugated dienes are more stable than isolated dienes, the formation of the conjugated diene is usually favoured over the isolated diene unless the structure prevents the formation of the conjugated system.

 

What would the products of the following sequences be ?
1-butene reacted with N-bromosuccinimide (NBS) then treated with KOH / heat
cyclohexene reacted with Br2 / CH2Cl2 then with KOH / heat