Welcome to part two of the organic
chemistry introduction, in part one we
went over all of these topics. Now let's
go over functional groups, do some
examples and I'll help you avoid a
common mistake students make. A
functional group is a specific type of
substituent meaning it is still attached
to a carbon in the carbon chain. Before
we go over all the common functional
groups it's important to know what an R
group is. An R group stands for the
rest of the molecule.
Here's an example of a functional group
if we wanted to write this as a generic
structural formula this carbon chain
would be the R group and the X stands
for one of these halogens. Let's go over
the most common functional groups. First
is an alkene this is the structural
formula and here's an example. As you can
see an alkene refers to the double bond
next is an alkyne which refers to a
triple bond. Onto an alkyl halide, alkyl
meaning it consists of carbon and
hydrogen and halide meaning it's a
halogen. Next is an alcohol an alcohol
has an OH bonded to a carbon chain or R
group meaning the rest of the molecule.
An ether has an oxygen in the center and
is surrounded by two R groups, the R
groups can either be the same or
different shown by R prime, the
apostrophe or prime means it's a
different group. You'll see that in this
example this R group is different from
the other. An epoxide has a triangular
shape with the oxygen being at the top
of this triangle-shaped carbon chain. A
ketone has a carbon that is double
bonded to oxygen and that carbon is
attached to two R groups, either the same
R groups or different ones. An aldehyde
is very similar to a ketone the only
difference is that it has a hydrogen
instead of two R groups. A trick to
remember this is that aldehyde has an H in it. A carboxylic acid
still has the same carbon double bonded
to oxygen but now there is an OH
instead of an R group or hydrogen. An
ester has a similar structure, it just
has an R group attached to the oxygen
instead of a hydrogen. An amide now has a
nitrogen attached to the carbon that is
double bonded to the oxygen. An amine
still has nitrogen but it does not have
a carbon double bonded to an oxygen to
remember the difference between an amide
and an amine it's hidden in the name an
amine has the minimum amount of atoms so
it's the one without the oxygen and this
is a phenyl group. Where a benzene ring
is attached to an R group. Note: another
functional group name is aromatic this
describes a benzene ring. Okay here is a
potential quiz or test question we are
asked to identify each functional group
in the following molecule. We have a
benzene ring which is aromatic, this
OH tells us it's an alcohol. Here we
have two R groups and an oxygen in the
center which is an ether and on top note
there is actually a hydrogen here making
this an aldehyde. Okay try these two on
your own and then I'll walk you through
all of the answers plus I'll let you
know what common mistakes to look out
for. So one common mistake I see is that
students think this is an alcohol group
but it's actually a carboxylic acid,
always check what that OH is connected
to. If it's connected to a carbon that is
double bonded to an oxygen then it's a
carboxylic acid, if it's connected to an
R group or really a carbon chain then
it's an alcohol like in this case. We
also have an amine right here, we have a
benzene ring which is aromatic. For the
second question I often see students
confuse an aldehyde for a ketone. So this
is an aldehyde because there's only one
R group and there actually is a hydrogen
right here now for a ketone there are
two R groups attached to a carbon that
is double bonded to an oxygen and we
also have an alcohol right here. Make
sure to check out more videos to help
prepare you for what's to come in
organic chemistry.
Also if you need more help I recommend
checking out the description box because
there you'll find other helpful
resources that I've hand-picked just for
you like homework help or tutoring and
so much more and remember stay
determined you can do this!
