Problem Set 2 –
Conjugated Systems
- 3-Buten-2-ol reacts with cold HBr
to give 15% 1-bromo-2-butene and 85% 3-bromo-1-butene. After heating, the
major product is 1-bromo-2-butene.
- Propose a mechanism to explain
the formation of the two products.
- Identify the main product
obtained in the reaction that is under thermodynamic control.
This is the more stable product which observed after longer reaction
times (thereby allowing equilibration to occur) or at higher temperatures:
- Identify the main product
obtained in the reaction that is under kinetic control.
- Identify the diene and the
dienophile that you would use to synthesize the following compound:
- Draw the structure of the
following Diels-Alder reaction:
- Treatment of isoprene
(2-methyl-1,3-butadiene) with catalytic amounts of acid leads to a variety
of oligomeric products, one of which is limonene:
a. Devise a detailed mechanism for the
acid-catalyzed conversion of two molecules of isoprene into limonene.
b. Two molecules of isoprene may also be
converted into limonene by a completely different mechanism, which takes place
in the strict absence of catalysts of any kind.
Describe this mechanism.
c. What is the name of the reaction?
The Diels-Alder reaction