Welcome back guys.
In this new video, we're going to be talking about group reactivity.
I know you guys just started chemistry one and you're learning all these new concepts
and new ideas and new calculation styles, but for some reason, your book wants to talk
a little bit about organic chemistry.
For those of you crazy enough to attempt organic chemistry in a couple semesters, just realize,
for now, the central principle of organic chemistry is all based on what we call the
functional group.
We're going to say the reactivity of most organic compounds are all based on the types
of functional groups present in it.
In this picture here, this large molecule that we have here is known as THC.
For some of you who don't know this, this is the active ingredient we find in marijuana.
The effects that marijuana has on certain people may range from different types of conditions.
Just realize, the effect that it has on us is all based on the different functional groups
present in it.
What we're going to do now is we're going to identify different types of functional
groups and then let's go back to THC and see which one of them are present in this molecule.
We're going to say that the simplest types of functional group is known as an alkane.
An alkane is just simply carbons and hydrogens single bonded to each other.
An example, we could have a carbon connected to four hydrogens, single bonded to them or
we could have two carbons connected to each other
and they're connected to hydrogens.
And it gets longer and longer and longer still.
That's the simplest type of functional group we can have.
The next type of functional group is called an alkene.
An alkene is the same type of concept except now, instead of being single bonded, we'll
have at least one double bond somewhere.
Now just realize, this is really early on in the semester.
We're going to say that you don't have to learn how to draw these yet, we'll eventually
get to that at some point, what's important is being able to identify it.
We're going to say an alkene, the distinguishing characteristic is that it has two carbons
that are double bonded to each other.
As long as you have a double bond somewhere, it will be an alkene.
An alkyne, the distinguishing characteristic is that we have two carbons triple bonded
to each other.
So same basic principle.
As long as you have a triple bond somewhere between two carbons, it's an alkyne.
An alcohol is we have a carbon that is single-bonded to an OH.
That carbon, in turn, is single bonded to other things, maybe hydrogens, maybe other
carbons.
That's an alcohol.
Here's an example of one.
The fact that we have a carbon connected to the OH and that carbon is single bonded to
other things makes it an alcohol.
An amine is when we have a carbon, at least one carbon, single bonded to a nitrogen.
We need at least one carbon single-bonded to a nitrogen.
We can have more than one carbon, we could have two, three or even four carbons connected
to that nitrogen, but as long as there's at least one, it counts.
In this example, that nitrogen is connected to two carbons, single bonded to two carbons,
it's still an amine.
An aldehyde we're going to have a carbon that is double bonded to an oxygen and single bonded
to a hydrogen.
We're going to say that this is called a terminal functional group, meaning that it's going
to be found at the end of our compound, either on the left end or on the right end.
So be on the lookout for that part.
That's what makes it an aldehyde.
Remember it could be on the right and on the left end.
A ketone, we have three carbons and then the middle one has a double bonded oxygen.
These carbons on the ends could be further bonded to a bunch of more carbons, it doesn't
really matter.
The most important part is this portion that makes it a ketone.
We could have –
this would be a ketone because we have the three carbons in a row and the middle one
out of the three has a double bonded to oxygen.
Again, we could have many more carbons on either end.
It's still a ketone.
A carboxylic acid is a carbon that's double bonded to an oxygen and then single bonded
to an OH.
That carbon will, in turn, be connected to maybe an H or maybe another carbon, another
chain, something else, but it's this portion that makes it a carboxylic acid.
Then finally our ester.
An ester, we have a carbon double bonded to an oxygen, single bonded to an oxygen, then
that oxygen is single bonded to another carbon.
It's this portion that make it an ester.
The molecules may be large or small, but you have to be on the look out for these distinct
portions.
It's this portion right here that makes it an ester.
Memorize what these functional groups are in order to master them, so then in a few
semesters when you get to organic, at least you know this right from the beginning because
functional groups play a major portion of all of organic chemistry.
Now we go back to THC we can take a look and see what type of functional groups are present.
We know that here are a bunch of carbons here.
Here we have two carbons, two carbons, two carbons, two carbons all double bonded to
each other.
All of those represent alkenes.
Then we're going to say that this carbon here is connected to an OH.
Now although it's not completely single bonded all the way around, it is single bonded to
at least one other carbon, so this would be an alcohol.
These would be the alkenes.
Then we'd say we have a lot of carbon-hydrogen chains here.
These would all be single bonded to each other.
These would be all alkanes.
Those are the major functional groups that you should know.
Those are the ones stated in your book, so those are the ones that you're responsible
for.
Just remember, functional groups are just really looking at the group and understanding
the connections.
You have to be on the lookout for these particular features, alkenes - double bonds, alkynes
- triple bonds.
Alcohol is a carbon connected to an OH.
Amines.
Just be on the look out for the specific parts that make them those functional groups.
If you can do that, if you can focus on those portions, it will be easier for you to identify
the functional groups present in large or small molecular compounds.