All right, so this first one would be no reaction.
We know that because we said that the second molecule can't be oxidized at all, so there's
no point in even drawing a product.
Now the third one is interesting because we talked about how this carbon right here has
only one bond to another carbon so that means if it has one bond to carbon, how many oxygens
can it possibly have?
Three.
What that means is that I need to draw a version of this carbon that's going to have three
bonds to oxygen.
If you looked at our intro to redox chart, where they talk about things that are getting
oxidized and things that are getting reduced, the version of carbon with three oxygens would
be a carboxylic acid.
So what I would do is I would draw that carbon with a double bond O and with an OH.
What that's going to do is now it's going to keep my carbon-carbon bond, so I'm not
breaking the rule, I'm not breaking that bond, but now I have one, two, three bonds to oxygen.
Cool.
Now, how about this last one, well this last one I'll move out of the way, so you guys
can see it.
This last one what you'll find is that that carbon once again, only had two bonds to – I
mean only had one bond to carbon, but it already had one, two bonds to oxygen.
So how many extra bonds to oxygen could it have?
Well, we just know that the rule says that you can only have four bonds and one of them
has to be a carbon so that means that the last third bond could also be an oxygen.
What I'm going to do here is I'm going to try to move out of the way here.
I'm going to draw this molecule once again also as a carboxylic acid.
Why?
Because basically when you're oxidizing something that has one bond to carbon, that means it's
going to have three bonds to oxygen.
And when you have three bonds to oxygen, you want it to look like a carboxylic acid.
When you have two bonds to oxygen, you want it to look like a ketone.
When you have one bond to oxygen, you want it to look like an alcohol, which is the one
that I have up there.
Bueno.
Pretty good.
Awesome.
Now what I want to do is I want to show you guys another reagent.
It turns out that even though we deal with strong oxidizing agents a lot, there's also
a reagent that's called a weak oxidizing agent.
Now a weak oxidizing agent would simply be one that doesn't oxidize multiple times.
The way that we're going to define it in particular is that it can only add one equivalent of
oxygen to primary alcohol.
That's really the only difference.
What that means is that it's going to do the same thing as all the other reagents, KMnO4,
chromium 6, same thing, except in one situation.
In a primary alcohol, instead of going all the way to a carboxylic acid, it's going to
go one equivalent instead of two equivalents of oxygen.
Let me show you what that looks like.
PCC is the name of this reagent and it is our weak oxidizing agent.
Would it be able to oxidize my secondary alcohol?
Absolutely.
It's going to do the same exact thing.
For PCC, I would get the same exact reagent here or the same exact product.
Would it be able to oxidize number two?
No.
Nothing can oxidize number two.
It's still no reaction.
Would it be able to oxidize number three?
Yes, it would, but this is our special situation.
Notice that I have a primary alcohol.
Whenever you have a primary alcohol, what that means is that for a strong oxidizing
agent I would have taken it to a carboxylic acid like this.
But for a weak oxidizing agent, like PCC, I'm going to go to an aldehyde instead.
That means that I'm actually going to draw this thing like this with an H instead of
an OH.
That's the biggest difference here.
That's actually the only major difference that we have with PCC is that instead of getting
carboxylic acid, we get an aldehyde.
Now you might be wondering, “Johnny, what do you mean by one equivalent of oxygen?”
All I mean is that notice that at the beginning, how many bonds to oxygen did we have?
We had one.
I'm just going to say one O. At the end of the strong oxidation, how many did we have,
bonds to oxygen?
We had three.
Three O. That means that if we had one oxygen to begin with, and three to end with, we added
two equivalents of oxygen.
Well, for PCC, instead of doing two equivalents of oxygen, now we're only going to add one
equivalent because now we have two bonds to O instead of one, which is what it started
with.
If you're starting with one and you ended with two, that means you only added one equivalent
of oxygen and that's what this definition has to do with.
But if you want to remember it, just say that primary alcohols go to aldehydes.
That's another way of saying it.
That's maybe less complicated and that's always right.
You could just say it like that the rest of your life if you want to and that's fine.
Let's get down to our last structure.
Would it be able to oxidize my four?
The answer is no.
This would be no reaction.
Why is that?
Well, because it's already an aldehyde.
Notice that aldehyde is the product of PCC.
PCC is going to make an aldehyde.
If we have an aldehyde already, is it going to do anything to it?
No.
Once it's an aldehyde, it's not going to oxidize it more.
This would be no reaction as well.
Just trying to show you guys the difference between PCC and the other oxidizing agent.
It's not that hard.
It's just a few details you have to keep in mind.
That said, let's go ahead and move on.