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Correction - 2-propylheptane should never be the name!

Correction - 2-Propylheptane should never be the name! Created by Sal Khan.

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  • blobby green style avatar for user Danny
    Why not delete both of these and redo the video? Imagine watching the previous video only before a test...
    (4 votes)
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  • blobby green style avatar for user dlkarpay
    I am not a bio major, and I do not have a strong scientific or mathematical background (just to help you with how to phrase the answer to my question). At , you count the longer carbon chain. My question is why did you count from 3 to 4? Are they not sharing the same carbon? I am not reporting a problem (I don't think), but only requesting an explanation. Thank you very much.
    (20 votes)
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    • blobby green style avatar for user hafeez.mustafa
      each end of a line segment is a carbon, so if he draws a (-), that would be two carbons. The 3 and four are opposite ends of a line segment and are thus two separate carbons, the line is just to show that they are bonded. for a shared carbon the line segments would originate from the same source. For example a (Y), indicates that the sented of the Y, where the "v" comes together, is one carbon bonded to 3 others, or "shared" by three others, the other carbons being the 3 lines that converge at the center. Hope this helps!
      (26 votes)
  • mr pants teal style avatar for user Carlos Bortoloto
    What about 4-propylheptane? I mean, both possible chains would have 7 carbons...
    (14 votes)
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  • hopper jumping style avatar for user Yuya Fujikawa
    So 2-Propylheptane doesn't exist?
    Thanks for a nice video!
    (4 votes)
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    • spunky sam blue style avatar for user Ernest Zinck
      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)
  • male robot hal style avatar for user Abdul Haseeb
    What is Keyton,Ester, Aldehyde,Alcohol,Ether & Carboxylic Acid in the functional group?Can someone tell me?
    (1 vote)
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    • spunky sam blue style avatar for user Ernest Zinck
      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)
  • leaf yellow style avatar for user Sean
    what if the chain on both sides are the same length?
    (2 votes)
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  • spunky sam blue style avatar for user @!0K
    Is "3,3 dimethyl prop-1-yne (or 3,3 dimethyl 1-propyne)" a correct name a the structure?
    (2 votes)
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  • blobby green style avatar for user Tasha Ornik
    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)
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    • female robot grace style avatar for user tyersome
      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)
  • blobby green style avatar for user Shastha Nair
    i really loved it but how come chemical bonding chapter is not available .....
    (1 vote)
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  • mr pink green style avatar for user H.M.Saathvik
    What is IUPAC naming of (CCl3)CCl
    (2 votes)
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Video transcript

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.