try applying these rules to name the following molecule (it's
not as hard as it might seem).
it step by step as outlined above.
Find the longest carbon chain in the molecule. First,
begin by finding the parent chain in the molecule--that is,
the longest possible chain of connecting carbons. Note that
the parent chain is not necessarily the chain that simply
follows from left to right. For example, if you were to count
the number of carbons directly from left to right in this
molecule you would get 7 carbons. This is not the parent chain,
however! If you start at the left and then count up where
the molecule branches, you find that there are 8 carbons by
taking this route. This is is the longest chain (dont be fooled
by professors hiding carbons in branches), and thus the parent
chain is octane (see table above).
Number the parent chain. The second step is to number
the carbons in the parent chain starting at the end closest
to the first substituent. It is important to number the molecule
from the correct end (in other words, in this example do you
number the alkane from right to left or left to right). Following
this rule, on this molecule you number from right to left,
as the 2-carbon substituent is closer to that end.
Name all the substituents. You then identify the names
of the substituents. In this case, the only substituent is
a 2 carbon group at the number 4 carbon. This is an ethyl
Put the substituents in alphabetical order. The next
step is to put the substituents in alphabetical order (ie.
ethyl before methyl) but since there is only one substituent
this is unnecessary.
Locate the substituent on the parent change by giving
it a number. Thus, the proper nomenclature of this alkane
is 4-ethyloctane. Note that a dash is used to separate the
number from the substituent.
try naming one!