Alcohols Naming alcohols
- We've already seen alcohols in many of these videos, but I
- thought it was about time that I actually
- made a video on alcohols.
- Now, alcohols is the general term for any molecule that
- fits the pattern some type of functional group or chain of
- carbons OH.
- And they use the letter R.
- And I've used it before.
- R stands for radical.
- And I don't want you to confuse
- this R with free radical.
- It means completely different things.
- R in this form really just means a functional group or a
- chain of carbons here.
- It doesn't mean a free radical.
- This just means it could be just something attached to
- this OH right there.
- Now another point of clarification, do not think
- that anything that fits this pattern is drinkable.
- Do not associate it with the traditional alcohol that you
- may or may not have been exposed to.
- Traditional drinking alcohol is actually ethanol.
- Alcohol is actually-- let me write out
- the molecular formula.
- CH3, CH2, and then OH.
- This is what is inside of wine and beer and hard liquor, or
- whatever you might want.
- You do not want to drink and maybe you might not actually
- want to drink this either, but you definitely do not want to
- drink something like methanol.
- It might kill you.
- So you do not want to do something like this.
- You do not want to ingest that.
- Might kill or blind you.
- This might do it in a more indirect way.
- So I want to get that out of the way and just so that we
- get kind of a little bit more comfortable with alcohols, and
- we've seen them involved in other reactions.
- We've seen hydroxides act as nucleophiles and Sn2
- substitution reactions create alcohols.
- But I want to do is just learn to get comfortable and really
- make sure we know how to name these things.
- So let's just name these molecules that I drew right
- before I pressed record right over here.
- So over here, like everything else, we always want to define
- the longest carbon chain.
- We have 1, 2, 3, 4, 5 carbons.
- So it's going to be pent.
- And there's no double bonds.
- So it's a pentane.
- So I'll just write pentane right then.
- And we're not going to just write a pentane because
- actually, the fact that makes it an alcohol, that takes
- precedence over the fact that it is an alkane.
- So it actually, the suffix of the word will involve the
- alcohol part.
- So it is pentanol.
- That tells us that's an alcohol.
- And to know where the OH is grouped, we'll start numbering
- closest to the OH.
- So 1, 2, 3, 4, 5.
- Sometimes it'll be called 2-pentanol.
- And this is pretty clear because we only have one group
- here, only one OH.
- So we know that that is what the 2 applies to.
- But a lot of times, if people want to be a little bit more
- particular, they might write pentan-2-ol.
- And this way is more useful, especially if you have
- multiple functional groups.
- So you know exactly where they sit.
- This one is harder to say.
- 2-pentanol is pretty straightforward.
- Now let's try the name this beast right over here.
- So we have a couple of things going on.
- This is an alkyne.
- We have a triple bond.
- It's an alkyne.
- We have two bromo groups here.
- And it's also an alcohol.
- And alcohol takes precedence on all of them.
- So we want to start numbering closest to the alcohol.
- So we want to start numbering from this end
- of the carbon chain.
- And we have 1, 2, 3, 4, 5, 6, 7, 8 carbons.
- We want to call it an octyne.
- But because we have an alcohol there, we want to call this an
- octyne-- let me make it very clear.
- So oct tells us that we have 8 carbons.
- Now we have to specify where that triple bond is.
- The triple bond is on the 5 carbon.
- You always specify the lower number of the carbons on that
- triple bond.
- So it is oct-5-yn.
- That tells us that's where the triple bond is.
- And then we have the OH on the 4 carbon.
- So 4-ol.
- And now we have these two bromo groups
- here on the 7 carbon.
- So it's 7,7-dibromo oct-5-yn-4-al.
- And this would all be one word.
- Let me make sure that you realize that
- this should be connected.
- I just ran out of space.
- So that's probably about as messy of a thing you'll have
- to name, but just showing you that these
- things can be named.
- Now let's think about this one over here in green.
- So we have 1, 2, 3, 4, 5, 6 carbons.
- So it's going to be a hex.
- And they're all single bonds, so it's a hexane.
- It's a cyclohexane.
- But then of course, the hydroxide or the hydroxy group
- I should call it, takes dominance.
- It's a hexanol.
- So this is a cyclohexanol.
- And once again, that comes from the OH right there.
- And you don't have to number it.
- Because no matter what carbon it's on, it's on the same one.
- If you had more than one of these OH groups, then we would
- have to worry about numbering them.
- Let's just do this one right over here.
- So once again, what is our carbon chain?
- We have 1, 2, 3 carbons.
- And we have the hydroxy group attached to
- the 1 and the 3 carbon.
- Prop is our prefix.
- It is an alkane.
- So we would call this-- and there's a couple
- of ways to do this.
- We could call this 1 comma 3 propanediol.
- Actually, I don't have to put a dash their.
- And over here, we would add the E because we have the D
- right there.
- So it's propanediol.
- If it wasn't diol, it would be propanal.
- You wouldn't have the E, D and the I there.
- So this would specify we're at the 1 and the 3 carbons.
- We have the hydroxy group.
- Or this could also be written as propane- 1, 3- diol.
- And once again, the di is telling us that we have two of
- the hydroxy groups attached to this thing.
- But either of these things are ways that you would see this
- molecule named.
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At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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When naming a variable, it is okay to use most letters, but some are reserved, like 'e', which represents the value 2.7831...
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This is great, I finally understand quadratic functions!
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At 2:33, Sal said "single bonds" but meant "covalent bonds."
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