Leah here from www.Leah4Sci.com and in this
video, I will show you how to name ethers.
An ether is a molecule typically written out
as R bound to O bound to R prime where R simply
represents the rest of the molecule or some
carbon chain and R prime can either be the
same R group or a different R group.
For example, we can have an ether created
by connecting two methyl groups to an oxygen
or creating both a methyl and an ethyl group
to an oxygen.
There are two common ways to name ethers.
The IUPAC rules follow the same rules we�ve
been using for naming organic compounds. You
start with your longest carbon chain as your
parent chain.
On the left we have methyl giving me a first
name of �meth�. Only single bonds gives
me a last name of �ane�. The shorter carbon
chain attached to the oxygen becomes an alkoxy
substituent where you simply take the prefix
for the carbon number and add the word �oxy�.
In this case we will have methoxy. Since carbon
1 is understood, we ignore the number giving
this a final name of methoxymethane.
Same thing applies to my second ether. In
this case my longest carbon chain has two
carbons, giving me a first name of �eth�.
Only single bonds gives me a last name of
�ane�. A one-carbon substituent on the
oxygen gives me a 1-methoxy. Once again carbon
1 is understood and can be ignored for a final
name of methoxyethane.
The common name for an ether involves naming
the two substituents that are attached to
the oxygen followed by the word �ether�.
If the two groups are different, you can arrange
them in alphabetical order.
Looking back at the first one, I have a methyl
group on the left. It gives me methyl. A methyl
group on the right would give me another methyl
but since it�s two of the same, I will use
dimethyl followed by the word �ether�.
On the right we have both a methyl and an
ethyl. Arranged in alphabetical order gives
me ethyl for the longer chain, methyl for
the shorter chain, followed by ether.
When the ether is part of a larger molecule,
you still follow the same rules for naming
organic compounds. In this example, we start
by identifying the parent chain and numbering
from the side that gives the ether the lowest
number.
In this case, I number from the left and get
a total of four carbons for a first name of
�but�. Having only single bonds gives
me a last name of �ane�. I have a two-carbon
ether substituent coming off of carbon 2 for
a prefix of �2-ethoxy�. Putting the name
together, I get 2-ethoxybutane.
If you�re given an ether with cyclic substituents,
don�t let the apparent complexity fool you.
We will start by identifying the parent chain
and follow the regular naming. In this case,
six carbons gives me a first name of �hex.�
Single bonds gives me a last name of �ane�
and the fact that it�s a ring gives me a
cyclo.
Since my oxy substituent is five carbons in
a ring, I have the prefix cyclopentoxy. The
number 1 is understood given that I have nothing
else on the molecule, giving me a final name
of cyclopentoxycyclohexane.
When you have more than one ether on a molecule,
you name it the same way. Include a number
for the carbon holding each ether and include
the word �di� to show that you have 2.
I start by identifying and highlighting my
parent chain. I have a total of five carbons
on the symmetrical molecule allowing me to
number from either direction. Five carbons
gives me a first name of �pent�. Only
single bonds gives me a last name of �ane�.
Both ethers have two carbons appearing one
on carbon 1, the other on carbon 5 for a prefix
of �1, 5-diethoxy�. This gives me a final
name of 1, 5-diethoxypentane.
When you have an alcohol and ether on the
same molecule, the OH group takes priority.
In this case, the molecule is numbered so
that OH rather than OCH3 gets the lower number
which means I have to number from the right.
Four carbons gives me a first name of �but�.
Only single bonds gives me a last name of
�ane�. Since the alcohol is higher priority,
I have a functional group of �2-ol�. The
ether is my substituent giving me 3-methoxy.
Pulling 2 in front of the first name means
that O will directly follow E and so I have
to drop the letter E for a final name of 3-methoxy-2-butanol.
When you have two carbons and an oxygen in
a ring, this is called an epoxide or oxirane
and will come up a lot in organic chemistry
reactions. Therefore in the next video, we
will look at how to name these specifically
in detail.
