Basic Organic Nomenclature
Associate Professor Emeritus UBC (Okanagan)
6. Aromatic Compouds
I Monosubstituted Benzenes
Aromaticity is a feature of certain planar, fully conjugated ring systems, where the 'whole is more
than the sum of the parts' in that the ring is more stable than might be expected by considering
the stability of the parts it is made from. Perhaps the prime example of this phenomenon is
benzene, a six-membered ring system which has quite a different stability and geometry,
and hence chemistry,
than expected for cyclohexa-1,3,5-triene, the name for the 'sum of the parts'. As a consequence of this
I prefer the symbol: in preference to the symbol:
to indicate the benzene ring, though both are
I. Monosubstituted Benzene Derivatives
- 1a. For those substituent groups which are named only with prefixes, often the prefix is attached to the
parent name in the way we have become used to.
- 1.b. Exceptions to this rule are found in that a few derivatives have common names which have
been accepted into the IUPAC system. These will have to be learned!
- 2. If the benzene ring is on a carbon chain which is used to form the root name, then the
benzene ring uses the prefix: phenyl.
- 3. Most other monosubstituted benzenes have common names which have been accepted into the
IUPAC system. And you've guessed it: they must be learned!
Simple amides derived from aniline can be named as 'anilides':
Esters of phenol use the name 'phenyl':
Ethers of phenol can use the prefix 'phenoxy' if necessary:
Other ketones with a benzene ring in them can use the prefix 'phenyl' for the ring:
Esters of benzoic acid are termed 'benzoates':
Self Assignment Questions
Review Alkanoates, Esters
Next page : Disubstituted Benzenes
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