Amides, Anhydrides, Esters and Acyl Chlorides

Carboxylic Acid Derivatives - Amides, Anhydrides, Esters and Acyl Chlorides

What I want to do in this video
is talk about a bunch of

molecules or classes of
molecules that can be derived

from carboxylic acid.

And just to show a specific
example I'll show things that

can be derived from
acetic acid.

And just as a review, acetic
acid looks like this.

The common name, as I just said,
is acetic acid, and if

you want to use the systematic
name, you look for the longest

chain, which is right
over there.

There's two carbons.

So we use the eth- prefix, so
it's ethan-, and since this is

a carboxylic acid, it
is ethanoic acid.

Now, the derivatives of acetic
acid, and we can later

generalize this to all
carboxylic acids.

We really just have to change
what's going on in this carbon

chain right here.

It won't have to necessarily
just be two carbons.

It can just keep going.

It could have benzene rings,
whatever, and that would

change the name.

But really, I just want to give
you the gist and the gist

of the naming.

So if we were to replace this
hydroxyl group with an amine,

and in future videos we'll see
how that is done, so let me

just draw the acyl group.

So the acyl group is just
that right over there.

And we're just going to keep
changing what's bonded to the

acyl group right over here.

So if this is bonded to an
amine, so let me draw-- well,

this would be the simplest amine
right over here, which

would be NH2.

This thing right here it's
called an amide, and if we

were to give this its common
name, it would be acetamide.

This particular example
would be acetamide.

And if we wanted the systematic
name for it, it

would be ethanamide.

You have two carbons right there
so it is ethanamide.

Now the natural question is,
all amines won't just be

primary, you might have other
things other than hydrogens

attached to it, other radical
groups, other carbon chains,

so how do you name those?

And so if you had a molecule
that looked like this, and

actually, let me just change
things up a little bit so that

we diverge a little bit
from the ethane route.

So let's say you had three
carbons bonded or part of the

acyl group right there.

And then, we are bonded to a
nitrogen, which is bonded to a

methyl group and then
another hydrogen.

In this case, you start naming
with this methyl group right

here and to show that that
methyl group is attached to

the nitrogen, you call
this N-methyl.

And then you look at the chain
that forms the acyl group, the

carbon chain.

We have one, two, three carbons
so it is propanamide.

If you had another methyl here
you would say N comma

N-dimethyl.

If you had a methyl here and
a propyl group here, you

would've called it
N-methyl-N-propyl-propanamide.

So hopefully that gives
you a sense of amides.

Now, and this is something we've
seen before so it's a

little bit of review, if you
have something that looks like

this, I'll have it attached
to a methyl

group right over here.

We've seen this before.

This is an ester.

And if we have an-- let me
actually make the part that

makes it an ester in blue
to diferentiate it.

We keep substituting what is
attached to the acyl group.

Let me label it.

This right here is called
an acyl group.

That right there is
an acyl group.

So right over here, for the
ester, if we were to give it

its common name, and we've
seen this ester

before, it is acetate.

And if we wanted to give it its
systematic , name you look

at the longest chain, one, two
carbons so it is ethan-- and

you don't call it ethanoic
acid anymore.

You call it ethanoate,
just like that.

Now, the next one, and we
haven't seen this one before,

and it looks complex, but when
you really break it down into

its constituents,
it's not so bad.

So let's say we have a molecule
that looks like this.

So we have one acyl group bonded
to an oxygen, which is

bonded to another acyl group.

So it's almost like you have two
carboxylic acids that have

been joined together.

And you really do have two
acyl groups joined by an

oxygen here.

This is called an anhydride.

And they look very complex, but
you just have to realize

they're two carboxylic acids
attached to each other and

usually the same one.

Most anhydrides you're going
to see in organic chemistry

are formed from the same
carboxylic acid, so how ever

many carbons you have on this
end, you're normally going to

have on this end.

So the way the name these is you
name it just the same way

that you would have named the
carboxylic acid, but instead

of writing the word acid, you
write the word anhydride.

So this right here would
be acetic anhydride.

It's derived from acetic acid.

This right here is
acetic anhydride.

Or the systematic name is, we
have one, two carbons so it's

ethanoic anhydride.

And just to make things clear,
if this molecule instead of

that, if we had something that
looked like this, where the

carbons chains on either
end had three carbons.

One, two, three, one,
two, three.

We would call this propanoic
anhydride.

In the unusual circumstance, and
it is unusual, where you

would see different carbon
chains here, you would list

each of them.

So if this had two here and
three here, it would be

ethanoic propanoic anhydride.

But that is very,
very unusual.

Normally, these carbon chains
on either end of-- or both

acyl will groups will contain
the same number of carbons.

Now, the last carboxylic acid
derivative that you should

know about, and we've already
seen it, are the acyl halides,

and, in particular, the
acyl chlorides.

So let me draw it
right over here.

So you have your acyl group
right there and then it is

bonded to a chlorine and this
right here is an acyl

chloride, maybe the most
intuitive name.

This right here is an acyl
group and then you have a

chlorine, so it's an
acyl chloride.

And we've seen this exact
acyl chloride.

It's derived from acetic acid,
so this is acetyl chloride.

But if you wanted to give it
its systematic name, and we

haven't seen it's systematic
name before, we have one, two

carbons so it is ethanoyl.

This tells us that we are
dealing with an acyl group.

Ethanoyl chloride is how
we would name this.

And if this had three
carbons, it would

be propanoyl chloride.

So, hopefully, that gives you
at least a good introduction

to the differences in structures
of all these groups

and an introduction
to naming them.

In the next video, we'll talk
a little bit about the

relative stabilities and then
it'll give you good intuition

on which direction a
reaction might go.

Are you more likely to go from
amide to an acyl chloride or

from an acyl chloride to an
amide or anything in between?