McMurry (Kap.4,9)

Question 1

What is it called when two to more cycloalkane rings are fused together, along a common bond to construct a “polycyclic molecule” - for example decalin.

Answer 1

It is called a polycyclic molecule

Question 2

What does the “bridgehead carbons” mean?

Answer 2

the carbon atoms in a bicyclic compound (a molecule containing two fused or connected rings) where the two rings are joined together. These carbons are part of both rings and form the points at which the two rings are connected.

Question 3

Can a polycyclic ring exist both in a cis and trans form?

Answer 3

Yes.

In CIS-decaline for example, the HYDROGEN ATOMS on the bridgehead carbons are on the same side/face if the rings.

In the TRANS-decaline, the HYDROGEN ATOMS on the bridgehead carbons are on the opposite sides of the ring.

Question 4

How can a polycyclic ring be illustrated?

Answer 4

By a normal skeleton structure or a chair conformation.

Note that the hydrogen atoms on the bridgehead carbons either are on the same side (both wedged or hatchet), or opposite sides (one hatchet and one wedged).

Question 5

What is norbornane?

Answer 5

bi/polycyclic hydrocarbon.

2 carbon bridges (one on each side)

2 bridgehead carbons.

1 carbon bridge.

Nonsubstituted norbornanes as camphor are found widely in nature.