1.1 Acyclic Hydrocarbon Systems
9
1.1.2
Branched Systems
Branched saturated and unsaturated acyclic hydrocarbons are named as
follows: after the main chain has been identified the side chains are
attached thereto as substituents. To define the parent chain the following
order of seniority is to be observed (see also Section 6.1, p. 178):
a) the main chain must have the maximum number of double and triple
bonds together.
b) if the foregoing criterion still leaves of choice or, as in the case of saturated systems, is irrelevant, the highest number of C atoms is decisive.
c) if there is still a choice the highest number of double bonds defines the
main chain.
d) if a decision still proves impossible, then that chain which has the
largest number of side chains takes precedence.
The main chain thus defined is then numbered according to the principles
already specified for unbranched systems. Side chains which in turn can
bear side chains of their own are treated analogously. If connecting the partial structures offers a choice, lowest possible locants are given to linking
positions. If, in the case of multiple side chains, all the above priority criteria are exhausted, alphabetical order comes into play. This also holds for
the citation order of side chains, irrespective of their connectivity locants.
6
1 12/1
/ """"""1 2,3,5-Trimethylhexane
1 1
6-Methyl-5-propylundecane
':::::
4-Ethyl-5-methylocta -2,6-diene
1-\\~_
~5 = - 8
5-Ethyl-4-methyloct -2-ene-6-yne
9
1.1.2
Branched Systems
Branched saturated and unsaturated acyclic hydrocarbons are named as
follows: after the main chain has been identified the side chains are
attached thereto as substituents. To define the parent chain the following
order of seniority is to be observed (see also Section 6.1, p. 178):
a) the main chain must have the maximum number of double and triple
bonds together.
b) if the foregoing criterion still leaves of choice or, as in the case of saturated systems, is irrelevant, the highest number of C atoms is decisive.
c) if there is still a choice the highest number of double bonds defines the
main chain.
d) if a decision still proves impossible, then that chain which has the
largest number of side chains takes precedence.
The main chain thus defined is then numbered according to the principles
already specified for unbranched systems. Side chains which in turn can
bear side chains of their own are treated analogously. If connecting the partial structures offers a choice, lowest possible locants are given to linking
positions. If, in the case of multiple side chains, all the above priority criteria are exhausted, alphabetical order comes into play. This also holds for
the citation order of side chains, irrespective of their connectivity locants.
6
1 12/1
/ """"""1 2,3,5-Trimethylhexane
1 1
6-Methyl-5-propylundecane
':::::
4-Ethyl-5-methylocta -2,6-diene
1-\\~_
~5 = - 8
5-Ethyl-4-methyloct -2-ene-6-yne