Organic Chemistry Naming Examples 2 Organic Chemistry Naming Examples 2
Organic Chemistry Naming Examples 2
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- I've pre-drawn some molecules here.
- Let's see if we can use what we know to name them.
- So what do we have?
- This first molecule right here, I have a bunch of rings.
- This is a one, two, three, four, five, six carbon ring.
- These are each four carbon rings: one, two, three, four,
- one, two, three, four, so the largest ring is essentially
- going to be our backbone.
- It's going to be this six-carbon ring right here:
- one, two, three, four, five, six carbons.
- That is a cyclohexane, all double bonds.
- That's where we get the -ane, six carbons hex-, it's in a
- cycle, cyclo-, and then we have two of
- these four-carbon rings.
- So four carbons, we're dealing with the prefix
- but-, but- for four.
- We've got two of them, so both of these are butyl groups.
- But they're in a cycle, so they're
- actually cyclobutyl groups.
- We have two things attached to this ring right there.
- If we only had one thing attached to it, you wouldn't
- have to number it.
- But when you have two things, you start
- numbering at one of them.
- Let's say we start numbering here, and you go in the
- direction so that the next group has the lowest number.
- So in this case, you want to go in the
- counterclockwise direction.
- If we went this way, it would be one, two,
- three, four, five.
- This guy would be a five.
- If we go in the counterclockwise, it would be
- one, two, three.
- This guy will only be a three.
- So this right here, we have two cyclobutyls, so it's
- We have two of them and they are at the
- one and three positions.
- So at the one and three position, I have two
- cyclobutyls on my cyclohexane main ring.
- Let's try this one right here.
- I have a five-carbon ring, one, two, three, four, five
- right there, and then I have a one, two, three, four, five,
- six-carbon ring right there, so this is going
- to be the main ring.
- That is a cyclohexane.
- It has six carbons on them in a cycle, all single bonds.
- Attached to that, I have a cyclopentyl
- group, -yl for the group.
- This is a cyclopentyl group on it.
- We don't have to number it because it's only one group
- attached to the main ring.
- If there was another group, we would have to number it like
- we did up here.
- This is cyclopentyl.
- That's this part right here.
- Cyclopentyl attached to cyclohexane:
- Let's try this one over here.
- The first thing we want to do, there's no cycles here, but we
- have to identify the longest chain.
- To do that, let's just count it out.
- It could be one, two, three, four, five, six, seven.
- That's not the longest chain.
- Maybe it's one, two, three, four, five, six, seven, eight.
- That looks like the longest chain, so let's make that the
- longest chain.
- Let's make that the longest chain right over there.
- We want to start numbering in the direction so we encounter
- the first attached groups first. We do want to start
- numbering down here, because we have groups attached right
- on the two carbon.
- If we started over here, we'd have to go pretty far until
- something's attached.
- So we go one, two, three, four, five, six.
- We know we're dealing with an octane, all single bonds.
- It's not a cyclooctane.
- It's not in a cycle, so we know we're
- dealing with an octane.
- Now we just have to add the groups to it.
- So what do we have here?
- This right here is just one carbon
- attached to the main chain.
- This is another carbon attached to the main chain.
- Both of these right here are methyl groups.
- Meth- is for one carbon.
- Those are methyl groups.
- If you look at all of them, these are
- the only methyl groups.
- These two up here aren't methyl groups, so we have two
- methyl groups on our entire chain, so
- it's going to be dimethyl.
- Both of the methyl groups our at our two position, so this
- is going to be 2,2-dimethyl.
- This part right here is 2,2.
- That right there is 2,2-dimethyl.
- We're going to decide what order to write it after we
- figure out what these are called because it has to be in
- alphabetical order.
- This is 2,2-dimethyl.
- The whole chain is an octane.
- What are these over here?
- How many carbons do we have here?
- One, two, three.
- They actually look the same.
- We have one, two, three here.
- We have one, two, three there, so these
- are both propyl groups.
- If we deal with common names, this is kind of that Y shape.
- You could call it sec-propyl because this carbon right here
- that's attached to the main chain is attached
- to two other carbons.
- But the more common one, because it forms this Y shape,
- is isopropyl.
- We have two isopropyl groups.
- These are both isopropyl.
- We would have diisopropyl.
- They're occurring at the four and five positions, two
- isopropyls at four and five.
- This is 4,5-diisopropyl.
- That's that group and that group right there are
- accounted for with this.
- Now we have to just figure out the order that we write it in.
- You ignore the di- or the tri- out front and you just look at
- them in alphabetical order.
- We have an I for isopropyl.
- We have an M for methyl.
- Let's write the isopropyl first. I've actually seen some
- people want to go for the p, but the main thing I ignore is
- just the di- or the tri- in front of the isopropyl.
- You shouldn't involve that.
- But everything after that, you do involve.
- So I'll write the isopropyl first. I comes before M, so
- this is going to be-- if we were going to write the whole
- thing, this is going to be 4,5-diisopropyl, 2,2-dimethyl.
- Actually, this should be a comma here.
- 4,5-diisopropyl- 2,2-dimethyloctane.
- And we're done.
- But this was just the common name.
- You might remember that when we deal with iso- or sec- or
- tert- butyl or propyl, that's the common name.
- If we want the systematic name, we can start at where we
- are attached to the main chain and view that as one and then
- make the longest chain with that as one.
- And so you could say that we have a chain there and this
- would be both of these cases.
- So this is one, two carbons.
- Two carbons, we're dealing with an ethyl.
- And on the first carbon, you have a methyl attached to it.
- So you could also call each of these groups a 1-methylethyl
- instead of an isopropyl.
- So you can either say isopropyl for each of these
- groups or you could call each of them a methylethyl if you
- do systematic naming.
- We have two of these 1-methylethyl groups, just
- like we had two isopropyl groups.
- If you're using common naming, you can say diisopropyl to say
- you have two of these groups.
- When you're using systematic naming, you don't say
- di-1-methylethyl, although that would probably would get
- the point across.
- You use bis-.
- Since we have two of them, instead of writing di-, you
- write bis-.
- You write bis-(1-methylethyl) That means you have two of
- these things right there, and it's still in the four and the
- five position.
- If you look at it in alphabetical order now,
- methylethyl comes after methyl, right?
- So the order will now change.
- So now if you want to write it with systematic naming, it
- would be written as 2,2-dimethyl.
- That's these two guys.
- 2,2-dimethylethyl, then you would write this guy, so the
- order changed for the two groups just based on how
- they're named.
- Bis-, and then over here you have two 1-methylethyl groups.
- I know it's confusing, but when you just break it down,
- it actually makes a reasonable amount of sense.
- You have two of these methylethyl groups.
- Oh, sorry, I forgot where they're located.
- So we have them at the four and five position, so in the
- four and five position, we have two, so
- bis-(1methylethyl) groups.
- I know it's a little daunting now, but it all makes sense
- when you break it down.
- And then we can just add the octane at the end.
- Let me scroll over to the right a little bit.
- Octane, and we're done..
- Now this might seem more confusing, but when you break
- it down, it makes sense.
- We have octane as the backbone.
- We have two methyls.
- They're both sitting on the two position.
- So you have two methyls sitting on the two position,
- and then you have two 1-methylethyl groups sitting
- at the four and five positions.
- So in the four and five position, 1-methylethyl.
- You have an ethyl, and in the one position you have a
- methyl, so that's all it's saying.
- Or another way to think about it, just in case this doesn't
- confuse you enough, you could call it that, or you could say
- these two things are the same thing: common naming,
- Hopefully, you found that useful.
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