Naming Examples 4 - Organic Chemistry, Chemistry Video Lecture - JEE | Best Video for JEE

Let's see if we can name
this guy right here.
In all of these problems, I
guess you can call them, we
look for the longest chain or
the longest ring, and this one
is pretty obvious here.
The ring in the middle is
clearly the longest carbon
structure here.
It has one, two, three,
four, five, six,
seven, eight carbons.
Let me highlight that.
It is eight carbons, so we will
be you using the prefix
oct-, and it is in a cycle, so
it will be cyclooct-, and it's
all single bonds, so
it's cyclooctane.
This right here tells us that
our core is cyclooctane.
Now let's look at the different
subgroups or the
different branches off
of the main ring.
Over here, we have a one, two,
three, four-carbon group.
It is in a cycle or it's in
a ring, so this is cyclo-.
Four carbons are but-,
cyclobutyl, -yl because it's a
subgroup or it's off of the main
chain or the main ring,
so that is our cyclobutyl
right there.
We also have another cyclobutyl
right here, four
carbons in a ring, so that's
another cyclobutyl.
Up here, we have three
carbons in a cycle.
The prefix for three carbons
is prop-, so this is
cyclopropyl.
Then down here, let's start with
the common names, because
those tend to be a little
bit easier.
We have one, two, three,
four carbons.
Actually, we have it
there and there.
One, two, three, four, these
are the same groups.
We're going to be dealing with
but- if we do common names,
and you see it has
this Y shape.
We're kind of connected to the
base of the Y in either case,
so we are dealing
with isobutyl.
The Y shape tells us that we're
dealing with iso-, isobutyl.
That's both of these
right there.
Now, we have to figure out how
we're going to number, where
we're going to number ourselves
on this ring.
And to do that, we look for
the group that is first
alphabetically.
This is a little bit of a
confusing point sometimes.
If this was a tert-butyl or
sec-butyl, we would consider
the B, but when it's isobutyl,
it's all considered one word,
so we'll consider the I.
We need to compare the I to the
C, to the C, to the C, so
the C's definitely
win out on the I.
If we look at all of these
cyclos, cyclobutyl definitely
takes precedence over
cyclopropyl.
It comes first alphabetically.
Let's make our starting point
this cyclobutyl, although you
could have made it that
cyclobutyl as well, so we'll
make that our starting point.
We're going to go in a clockwise
direction, so that
we could get to this one first,
so that the next group
is only going to be a two.
Otherwise, the next group would
have been at three.
So one, two, three, four, five,
six, seven, so this is a
1-cyclobutyl.
This is a 6-cyclobutyl.
This is a 7-cyclopropyl.
This is a 2-isobutyl, so this is
a 2-isobutyl and this is a
4-isobutyl.
We want to write them all
in alphabetical order.
The cyclobutyls win, so we
have a cyclobutyl at one.
We have a 1-cyclobutyl.
We also have a 6-cyclobutyl.
we have two of them, so
it is dicyclobutyl.
Let me capitalize since that's
where we're starting.
So we got those two guys out
of the way, and then
alphabetically, cyclopropyl
is next, so then we have a
7-cyclopropyl.
Let me do that in that orange
color of the cyclopropyl.
7-cyclopropyl, got that
guy out of the way.
Then at two and four we
have an isobutyl.
We have a 2,4-, and we have
two of them, so it is
diisobutyl, and then finally
cyclooctane.
We got the 2,4-diisobutyls out
of the way, and then we have
our cyclooctane, so I'll just
write the cyclooctane.
And we're done.
This was the common naming.
Now, if we want to do systematic
naming, we would
have to use something else
other than the isobutyl.
And to do that, let me
do that over here.
What you do is you use your
connection point as one, and
you just branch.
Let me do this in a color I
haven't used for before.
Green.
So let's make that our core
chain, so that is one, two,
three, carbons, so it's propyl,
and then on the second
carbon, on the number two carbon
that we are attached
to, you have a methyl group.
So this is 1-methylpropyl.
That's what each of these--
that's a 1-methypropyl and
then that is a 1-methylpropyl.
Another way to think about, an
isobutyl is the same thing as
a 1-methylpropyl.
This is the propyl part, and
then this right here-- let me
do that in that color--
that right there
is the methyl part.
Oh, sorry, this isn't
a 1-methlypropyl.
Let me be very careful
with my numbering.
This is the one carbon, two
carbon, three carbon.
The methyl comes off of
the second carbon.
So this is a 2-methylpropyl:
one, two, three.
Methyl comes off of
the second carbon.
This is a 2-methylpropyl
group.
And now when we look at it
alphabetically, methylpropyl
still comes after cyclobutyl, so
it definitely won't change
the numbering of things, and so
it still would be last. It
also comes after cyclopropyl.
If we were to do the systematic
naming, it would be
1,6-dicyclo-- there's something
very strangely fun
about this-- dicyclobutyl.
Then you have your cyclopropyl,
7-cyclopropyl.
It's like a secret code.
And then you have your-- now,
this is interesting.
You have two of these
guys, right?
Now you don't say di- when you
have this kind of more complex
naming or this systematic
naming.
Instead you use the word
bis-, so we have bis-.
So let me write it.
We're at two and four,
2,4-bis, this thing.
I can just bis-(2-methylpropyl).
So this part right here
is the exact part as
that part right there.
This the common name.
This is the systematic naming.
And then we have our
cyclooctane.