Organic Chemistry Naming Examples 1 Organic Chemistry Naming Examples 1
Organic Chemistry Naming Examples 1
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- I think we're ready now to tackle some more or even more
- complicated examples.
- So let's draw something crazy here.
- So let's see, let me draw a chain.
- Let me draw it like that.
- And so like we've done in all of the examples, you want to
- find the longest chain.
- We could count from here.
- One, two, three, four, five, six, seven, eight, or maybe
- it's one, two, three, four, five, six, seven.
- Or maybe it's one, two, three, four, five, six, seven,
- eight, nine, ten.
- That is our longest chain.
- Let me make that in green.
- So our longest chain here is in green.
- So this decane-- sorry, this backbone has
- ten carbons in it.
- The prefix for ten is dec-.
- It is an alkane since it has all single bonds, so we can
- write decane for the backbone.
- And then it has a group right here and this group consists
- of one, two carbons attached to the backbone.
- The prefix for two carbons is eth-, so
- this is an ethyl group.
- The -yl is because it's a group attached to the main
- alkane chain, so we call this ethyldecane.
- But we have to specify where the ethyl group is attached.
- And we want to give it as low of a number as possible, so we
- start counting on the side closest to it.
- So it's one, two, three, four, five, so this is
- Now let's complicate this a little bit more.
- So let me just to copy and paste this.
- So I have pasted it there.
- And let me complicate this molecule a little bit more.
- Let me add another ethyl group to it.
- So let's say we have another ethyl group over there.
- Now, what is this going to be?
- Well, the longest chain is still going to be that thing
- in green, so it's still going to be a decane.
- But now we have two ethyl groups, one on the five
- carbon, one, two, three, four, five, and then
- one on the six carbon.
- So we write here-- you might be tempted to write
- 5-ethyl-6-ethyldecane, which really wouldn't be wrong, but
- it would just be maybe more letters
- than you want to write.
- Instead you write 5,6-diethyldecane.
- The 5,6- tells us the two carbons on the main backbone
- that the ethyl groups are attached to, and the di- says
- that we have two ethanes.
- Or two ethyl groups, I should say, not ethane groups.
- Two ethyl groups, one over here and one right over here.
- Now, let's make it even more complex.
- Let's take our thing and let's make it even more complex.
- So let's copy it and let us paste it, edit,
- paste, just like that.
- Let's paste it.
- Let me make it a little bit lower over here.
- So the exact same thing we just dealt with, but let's add
- one more group to it.
- Let's say it looks something like this.
- Let's say on that five carbon-- let's say on that six
- carbon right there, I have a group that looks
- something like this.
- What is this is going to be called?
- And here we probably want to break it down a little bit.
- We still have the backbone, so it's still
- going to be a decane.
- But let's just do it step by step.
- So we know that this right here, this is an ethyl group.
- It's on the five carbon, so that is a 5-ethyl.
- This is another ethyl group on the six carbon,
- so that is a 6-ethyl.
- Now, we have this group over here.
- So how many carbons are on this group?
- Well, we have one, two, three carbons on it.
- We have three carbons on it, so we might want to just call
- it a propyl group, but notice something.
- We are attached to the carbon, and then it later
- branches off into two.
- It actually immediately branches off into two.
- So we could actually call this either sec-propyl, so this
- right here, we can either call it sec-propyl, or because it
- is connected away from the-- I guess it's connected directly
- to the branch the way a propyl group works.
- You could connect it and it immediately branches, because
- you only have three carbons.
- So just to clarify things, it's sec- because we're
- attached to two carbons right there.
- But sec-propyl isn't what people normally call it.
- They normally call it isopropyl.
- And the iso- root comes from anything of the form.
- So if I have a group that looks like this, this would be
- isobutyl, because we have one, two, three, four carbons, and
- we are attached right here, so this is where we would attach
- to the main backbone.
- If I have a group that looks like this,
- this would be isopentyl.
- I have one, two, three, four, five carbons.
- I'm attached away from the branch.
- But if we go one step closer, so we're attached just like
- this, we're attached to the original
- group, this is isopropyl.
- One, two, three carbons.
- Let me write-- isopropyl, isobutyl, isopentyl.
- Notice what the isos-- the isos are like Y's, I guess is
- the best way of thinking of it, and you're attached to the
- base of the Y.
- In this case, you're almost attached to the base of a V,
- but, hopefully, you get the idea.
- So the common name for this group would be isopropyl, or
- if we wanted to use the systematic naming, we could
- just start at one as being-- let me do this in a good color
- --as the carbon we are attached to, and then we only
- have two carbons right over there.
- So if we have two carbons, we're dealing
- with an ethyl group.
- And then you could say that you have a methyl group
- attached to the first carbon, so it would be 1-methylethyl.
- So this could either be called an isopropyl group, or a
- 1-methylethyl group.
- And in either case-- let me put that in parentheses.
- In either case, it's attached to the six carbon.
- So the prefixes are going to be on the six carbon on our
- main-- we have a 1-methylethyl, where the
- methyl is attached to the first carbon on the ethyl
- chain, or we could call this a 6-isopropyl group attached to
- the six carbon.
- Now, when we decide how to write it, how do we know--
- we're going to have to write essentially the
- ethyl and the isopropyl.
- We're going to have to write all of that in
- front of the decane.
- How do we decide whether to write the eth-
- or the propyl- first?
- Well, here you just do it in alphabetical order.
- And actually these little prefixes
- in front don't matter.
- So you compare the P to the E.
- Eth-, E comes first in alphabetical order, so this
- would be 5,6-diethyl.
- So even though D-- well, D comes even before E, but you
- don't even count that prefix.
- The E is what matters.
- Diethyl, and then we could say,
- This is the common name: 6-isopropyldecane.
- This would be the common name for it.
- If we want to use the systematic name, we would
- replace the 6-isopropyl with 6,1-methylethyl.
- So let me write that down.
- So let me just copy this part.
- So copy and paste right there.
- And then I can copy and paste this right here.
- Copy and paste.
- So it becomes 5,6-diethyl-6-1-methylethyl.
- I know it's very confusing when you see it, but when you
- break it down, you really could-- you would be able to
- draw this from the structure.
- And then finally you finish with a decane.
- So hopefully, these examples don't confuse you too much.
- In the next few videos, we'll do more and more examples.
- Because I think with the nomenclature on the organic
- chemistry, the more examples you see, the better.
- This is really core, so in the future you don't get confused
- when people throw out something like,
- 5,6-diethyl-6-(1 -methylethyl)decane.
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