Question

Explain and differentiate between the following terms.
a. Polycyclic compounds
b. Fused rings
c. Bicyclic compounds
d. Bridgehead C atoms
e. Bridge C atoms
f. Bridged bicyclics

Answer 1

a. Compounds containing more than one ring.

Both compounds (I) and (II) are polycyclic compounds.
b. Rings of (I) share a common (C---C) bone and are said to be fused
c. Compounds containing two rings, both (I) and (II) are bicyclic.
d. Brigehead C atoms are junction points for the rings (encircled in both the structures) C-9 and C-10 in (I) and C-1 and C-4 in (II).
e. and f. Bridge C atoms are in the chain connecting but not including the bridgehead C atom. Compound (II) is a briged biyclic because one or more Carbon atom separate the brigehead C atoms, whereas compound (I) is not bridged bicyclic.