- Representing structures of organic molecules
- Naming simple alkanes
- Naming alkanes with alkyl groups
- Correction - 2-propylheptane should never be the name!
- Common and systematic naming: iso-, sec-, and tert- prefixes
- Naming alkanes with ethyl groups
- Alkane with isopropyl group
- Organic chemistry naming examples 2
- Organic chemistry naming examples 3
- Naming a cycloalkane
- Naming two isobutyl groups systematically
- Organic chemistry naming examples 4
Correction - 2-Propylheptane should never be the name! Created by Sal Khan.
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- Why not delete both of these and redo the video? Imagine watching the previous video only before a test...(3 votes)
- actually, it's better this way. because we will remember this mistake and learn from it. I will never make the mistake again. so, it is actually a learning experience. :)(265 votes)
- What about 4-propylheptane? I mean, both possible chains would have 7 carbons...(14 votes)
- 4-propylheptane would imply the propane group is at the 4th carbon of a heptane. Its a proper name but not what is shown.(3 votes)
- So 2-Propylheptane doesn't exist?
Thanks for a nice video!(4 votes)
- 2-Propylheptane exists but not under that name. If you look for it on-line or in a chemical dictionary, you won’t find it.
In the same way, if your nickname is Yoshi, you will still exist and your friends will know who you are, but you won’t be found in any official records under that name.(11 votes)
- What is Keyton,Ester, Aldehyde,Alcohol,Ether & Carboxylic Acid in the functional group?Can someone tell me?(1 vote)
- An alcohol has an O atom with an H on one side and an alkyl group on the other side: R-O-H.
An ether has an O atom with an C on one side and a C on the other: R-O-R'.
An aldehyde has a carbonyl (C=O) group with a C on one side and an H on the other: R-(C=O)-H.
A ketone has a carbonyl (C=O) group with a C on one side and an C on the other: R-(C=O)-R.
A carboxylic acid has a carbonyl (C=O) group with a C on one side and an OH on the other: R-(C=O)-OH.
An ester has a carbonyl (C=O) group with a C on one side and an OR on the other: R-(C=O)-OR.(11 votes)
- what if the chain on both sides are the same length?(2 votes)
- If two chains of the same length are competing for selection as the main chain, you choose the one that has the lowest substituent numbers at the first point of difference.(5 votes)
- Is "3,3 dimethyl prop-1-yne (or 3,3 dimethyl 1-propyne)" a correct name a the structure?(2 votes)
- No, one of your "methyl" groups would go into the backbone of the molecule, so the name would be 3-methyl-1-butyne.(3 votes)
- Hi, In my chem uni study guide it says the longest unbranched chain. so it would be propyl heptane but your saying its not. Can you clarify if the longest chain you are showing here is branched or unbranched? im getting 2 different explanations and im not sure whats right.(2 votes)
- Try drawing out the structure for "2-propylheptane" and then figure out the longest unbranched chain.
You will find that the side chain is not a propyl group!
Consequently the correct name will be something different.(3 votes)
- Are there any specific formulae/methods to immediate know that if a name of a carbon compound is incorrect due to the video's illustration? i.e. the branched part is actually forming the principal chain.(2 votes)
- The easiest way I know of is to draw it out. You can see if Sal had just been drawing the compound without explaining everything aloud, it would be very quick to see that longer chain than the original You could do it mathematically, but it would be significantly more painful than just drawing the figure.(1 vote)
- Though a bit off topic... when naming halogens n a chain, is there a specific order to naming them? I/m reviewing for the MCAT and my textbook doesn't address the issue. Thank you.(2 votes)
In the last video, we tried to draw a 2-Propylheptane. And we did our best attempt at drawing it, but it was pointed out that this wouldn't even be called a 2-Propylheptane to begin with. So you actually should never see something called 2-Propylheptane. Let me show you what I'm talking about. So when do you see something like this, you might immediately say-- and the way we drew it was actually correct, it just wouldn't be called 2-Propylheptane. So you say heptane. So that is a seven carbon alkane. No double bond, so one, two, three, four, five, six, seven. And then on the second carbon, so you have one, two, three, four, five, six, seven, we have a propyl group. Propyl, that is three carbons. So on the second carbon we have a propyl group. That's three carbons. So that is one, two, three. And so the way we drew it was just like this. And so if someone gave you 2-Propylheptane, this would be what you would draw. But you wouldn't call this 2-Propylheptane. Because remember, if you're given the molecule you look for the longest chain and the longest chain here is not the heptane chain. It is not one, two, three, it is not this thing in magenta-- in this kind of mauve color. It's this chain where you start over here. If you start over here, one, two, three, four, five, six, seven, eight, nine, you actually get a longer chain. So this would actually be the backbone of this molecule right over there. That right over there would be the backbone, and so you would number it. You start numbering closest to the group that's attached, so one, two, three, four, five, six, seven, eight, nine. So you have nine carbons in your backbone, so we're dealing with nonane. We're dealing with nonane. And you have a methyl group: one carbon attached to the fourth carbon of our main backbone. So this is going to be four methyl, this is our methyl group right here, 4-Methylnonane. So it was brought up, I think the user name is Minoctu, and they correctly corrected me, that there would never be such a thing as 2-Propylheptane. I just made that up. If someone were to, kind of, label this molecule they would call it 4-Methylnonane and ask you draw it. But either way, both of these would point you in the right direction. This would just be the incorrect name for it, because you'd be looking at-- if someone gave you this molecule and you named it this way, that would be incorrect. So I apologize for this. This is 4-Methylnonane. If you do heptane you're not finding the longest chain.