- 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
Naming simple alkanes
Naming simple linear and cyclic alkanes. Created by Sal Khan.
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- So does something like isopropyl alcohol contain 23 carbon atoms? Being that iso in organic chemistry means twenty and prop three.(13 votes)
- Isopropyl alcohol is a "common name." The proper IUPAC name for isopropyl alcohol is 2-propanol or propan-2-ol. It only has three Carbons (notice the parent name is "propan" which means it is a saturated 3 carbon molecule) and the hydroxyl group (which makes it an alcohol) is on the 2nd carbon. If you continue to watch these videos you'll learn later why it's called "isopropyl alcohol." Hope this was helpful. -Chris(39 votes)
- So, what is the difference between a cyclo molecular carbon chain and a simple carbon chain?(5 votes)
- cyclic compound is a closed chain while simple compound is a continuous chain(1 vote)
- what will be the name of 20 number alkane???(7 votes)
- It's Icosane
Hope it helps!(1 vote)
- Are the hydrogens in5:43given in the question or should i know them myself?(5 votes)
- Well usually for alkanes, you should know how many hydrogens there are. You can use the formula C(x)H(2x+2). Specifically in5:43you should know how many hydrogens there are because Carbon needs four bonds to have 8 valence electrons and without the Hydrogen it only has two bonds, 4 electrons. So you know there must be two more bonds for each with a hydrogen.(5 votes)
- at around4:10sec Sal gives us some examples of naming the organic compounds, he gives eg of hexane, heptane etc. So i would just want to know that is this name only applicable for carbon-hydrogen molecules or single bond combination of carbon with other atoms also (eg chlorine).?(3 votes)
- Anything that ends in -ane indicates a base chain of carbon-carbon single bonds. Substituents (eg chlorine) are named by the number of the carbon they are on and the name of their functional group. For example, CH3CHClCH2CH3 would be 2-chlorobutane. This also applies to branches off the main carbon chain. For example, CH3CH(CH3)CH2CH3 would be 2-methylbutane.(3 votes)
- We know that carbon has the ability to self link by which it is able to create a big carbon molecule. why can't other elements use self linking as carbon does?(2 votes)
- If I understand your question correctly, it has to do with carbon having 4 valence electrons. It's not just that the carbons bond together, it's also that where carbon isn't bonded to carbon, hydrogen jumps in to fill the valence (because we want a full octet). If you draw out a chain of carbons alongside a chain of nitrogens or oxygens with the electrons drawn out (like a Lewis dot structure), you'll see that only the carbon can buddy up with hydrogen using single bonds to give each carbon a full octet. The nitrogen and oxygen either have to form double or triple bonds (which hydrogen can't do) or they have to violate their octet.(4 votes)
- What should we write when c- is said to be in branch,ring ,chains etc. form ?(2 votes)
- i think you write cyclo then followed by the name(2 votes)
- what if we had a ring combined of 6 carbons and 5 carbons but had 2 joint carbons to conclude a total of 9 carbons? how do we name it?(1 vote)
- It's kinda complicated.
Its proper name is bicyclo[4.3.0]nonane. Bicyclo = 2 rings, nonane = 9 carbons in total (6 + 5 - 2 that are shared in both rings), [4.3.0] means one ring goes 4 carbons around (the cyclohexane ring) from the bit that connects both rings, one ring goes 3 carbons around (the cyclopentane ring), and the bridge that connects both rings only has the 2 carbons that are part of both rings, so the last number is 0. You can get molecules with a bridge here which you'd use however many carbons are over top of the ring, but it's 0 in this case.(4 votes)
- The name of C6H6 is Benzene. But it should starts with prefix 'Hex' . Then why it
starts with 'Benz' ?(2 votes)
- You're correct about the "hex" prefix - the systematic name of benzene is in fact cyclohexa-1,3,5-triene. However, it's usually called benzene instead (the name comes from benzoin resin). If I had to guess why, I'd say it's because the name is shorter and more convenient, and has been used for a long time.(1 vote)
So when we name organic molecules, the core of what we think about is just how many carbons form the chain or form the ring that we're looking at? So let's say I have something like this. And hopefully, you're reasonably familiar with what this represents. And I'll review it a little bit. So let's say I have something like this. Let's say that that is the molecular structure right there. And so the first question you should be asking is how many carbons are there? And some of you might say, wait, how is that even a molecule? And just as a review, the end point of every line represents a carbon. So that's a carbon, that's a carbon, that's a carbon, that's a carbon, that's a carbon, that's a carbon. And we have one, two, three, four, five, six carbons and we have no double bonds. So if you have all of that information you're ready to name this molecule. And before I actually name it, let me just kind of give you all of the different prefixes. So if you have one carbon, the prefix is meth-. If you have two carbons, the prefix is eth-. And it's good to memorize at least up to about 10. And actually it kind of repeats after that. If you have three carbons, the prefix is prop-. Prop- like propane, and you've heard of ethane and methane. So you'll see all of that soon. Four, you're talking about but-. Five, and after five it kind of becomes the traditional prefixes that we associate with a lot of these numbers. So at five, it's pent-, like pentagon. Six, it's hex- like hexagon. Seven is hept-. Eight is oct-, like octagon. Nine is non-. Ten is dec-. And then after that it kind of starts to have a pattern here, and you're not going to really deal with things much beyond the teens, but I'll just write them down here just out of interest. Eleven is undec-. And for those of you who know French, I'm not one of them, but I know that one in French is une, or in Spanish, uno. So it's 1 and 10, 11. Twelve is dodec-. Do or dos, if you're speaking Spanish, for 2. Dec for 10, 2 and 10, that's 12. Thirteen, you could imagine what it's going to be. It is tridec-. Fourteen is tetradec-. A tetrapod is something with four legs. And after that it, becomes very systematic. At fifteen is pentadec-. Notice pent-, 5 and 10. Sixteen is hexadec-. Seventeen is heptadec-. So it just goes on and on and on. I don't think I've got to go-- anyway, it's hexadec-, heptadec-, octodec- is eighteen, nineteen is nonadec-, and then twenty is actually iso-. But we won't even go into that. This'll probably serve our purposes. I mean, I could go up to sixteen is hexadec-. So this is just how many carbons are in our longest chain. What I drew here is just one chain. So we could immediately-- let's try to name it. Well, how many carbons do we have here? Well, we have one, two, three, four, five, six carbons. So we'll be dealing with hex- as a prefix. And then to get, I guess, the post-fix on this prefix, or the kind of the root, you look to see if there are any double bonds here. And there are no double bonds here. And if we have no double bonds in this carbon chain, we're dealing with an alkane. This is called an alkane, which is a general term for all of the chains of carbons that have no double bonds on them, or no triple bonds, all single bonds. So in this situation, you take hex- for six, so this is hex-. And then, because it's an alkane, it gets the -ane from alkane. So this is hex-, this is hexane. Let's do another one. Let's say I have this thing right here. I'll draw-- let's make it even longer. So let's say I have that thing right there. So how many carbons do we have? We have one, two, three, four, five, six, seven carbons. They're all single bonds, so it's an alkane. So this will be seven carbons. It is heptane because we have all single bonds. Now, if things form a chain, or if things form a ring, I should say, we put the prefix cyclo- in front of it. So if I have-- let me show you what I'm talking about. So if I just have five carbons, one, two, three, four, so one, two, three, four, five. OK, so that's five right there. I have one, two, three, four, five carbons in a chain. If I just have five carbons in a chain like this, this would be pentane. But if I have five carbons and they form a ring, so let me draw it. So it's one, two, three, four, five carbons and it forms a ring. Let me make the drawing a little bit better. So it's really, I'm just drawing a pentagon. But notice, this has five carbons on it. I can draw the carbons here. Carbon, carbon, carbon, carbon, carbon. And just as a review, what you don't see is the hydrogens they're bonded to. Each of these guys have two bonds, so they must have two bonds with something else and those are going to be with hydrogen, And I'lll draw it here just as a bit of a review, but you notice very quickly, the drawing gets extremely messy when you draw the two hydrogens on each of these carbons. So it's a little bit over-- maybe I shouldn't be doing that. But there you go. So it becomes very messy when you draw the hydrogens, so it's better to just assume that they're there. If we don't draw all four bonds of the carbon, the other two bonds are going to be with hydrogen. So here, you might say, OK, this is an alkane, because I don't have any double bonds here. All of these are single bonds with the carbon. I have five carbons, so you might say this is pentane, but you have to think about one more thing. It's in a ring, so we add the prefix cyclo- to it. So this is, because it's a ring, we write cyclopentane. So let me just break that apart. This tells us that we're dealing with a ring. You see that this is a ring right there. This tells us that we're dealing with five carbons, and then this tells us right here, the -ane part, that tells us that they are all single bonds. All carbon-carbon single bonds. No double or triple bonds. All single bonds. So let's go the other way. Let's start with the word and let's see if we can figure out what the actual structure would look like. Let's say I have cyclononane. So what is this telling me? This tells me I'm dealing with a ring. That is a ring. It's going to have a ring structure. It's going to have nine carbons, nine C's, and then it's an alkane, so they're all going to be single bonds. So if I want to draw it, I want to draw nine carbons in a ring, it's not a trivial thing to draw. I'll try my best, so let's see, that's one, two, three, four, five, six, seven, eight. Let's see, let me draw it. I'll try a little a better shot at it. So, let's see, you have one, two, three, four, five, six, seven, eight, and then nine. And then you can connect the last. So let me make sure that this is-- and obviously, I could have drawn it better than that, but hopefully, you can see all of the edges here. So I have one, two, three, four, five, six, seven, eight, nine carbons. It's in a cycle. It's in a ring. I have nine carbons. They're all single bonded, so this is cyclononane, although there's probably better ways to draw that ring right there. So if someone were to tell you, octane, and that word might feel familiar to you from the gas station. They are literally talking about the molecule octane. And now you know, or at least you have a sense of what they're talking about. The oct- tells you that you have eight carbons. There's no cyclo- in front of it, so it's not a cyclo. It's just going to be a chain. And then the -ane part tells you that they're all single bonds, so it's just going to be eight carbons in a chain. One, two, three, four, five, six, seven, eight. It's just going to look like that. One, two, three, four, five, six, seven, eight. In the next few videos, we'll add more to these molecules and make the names even more complex.