6.2 Determination of the Most Senior Ring System
k) largest number of substituents expressed as prefixes,
1) lowest locants for all prefix substituents of the main chain,
m) most senior prefix substituent according to alphabetical order,
n) lowest locants for the most senior prefix substituents.
6.2
Determination of the Most Senior Ring System
179
The following criteria are examined sequentially until a decision is
reached.
a) largest number of most senior characteristic groups expressed as suffixes,
b) for heterocycles the ranking principles of Section 1.2.2.3 apply:
ba) heterocycles are preferred to carbo cycles,
bb) nitrogen-containing rings,
bc) most senior hetero element according to the "a" -term Tables 4,20,
bd) the ring system with the largest number of rings,
be) the ring system having the largest ring,
bf) the ring having the largest number of hetero elements,
bg) the ring displaying the greatest variety of hetero elements,
bh) the ring containing the largest number of senior elements,
bi) the ring with the lowest possible set oflocants before fusion,
c) for carbocycles too, the system containing the largest number of rings
is to be preferred,
d) the system with the largest individual ring when the first point of difference is evaluated,
e) the system containing the largest number of atoms common to two or
more rings,
f) lowest letters for fusion positions: naphtho[2,1-f]quinoline > naphtho[I,2-gJquinoline,