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Organic Chemistry

  1. Jan 16, 2005 #1
  2. jcsd
  3. Jan 24, 2005 #2

    It looks like it has C7H14 base, but can't make out the rest of it yet. Hope you figure out soon!

  4. Jan 24, 2005 #3


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    No real idea with the naming of multiple interconnected cyclic groups, but it certainly is an unstable cycloalkane, because of the highly strained 60 deg bond angles in the little triangle. Any of the three ways you look at it, there's a cycloheptane involved, so unless the style of naming changes when you have connected cyclic chains, I'd imagine this would be a cycloheptane of some kind. If not for the extra bonds, it could have been a 1-propyl,2-methylcycloheptane, but what it really is, I have no clue.

    This should definitely be moved to chemistry.
    Last edited: Jan 24, 2005
  5. Jan 24, 2005 #4


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    moving to chemistry...
  6. Jan 24, 2005 #5


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  7. Jan 25, 2005 #6


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    Wow ! Movies, could you explain how that works ?
  8. Jan 25, 2005 #7


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    I can try. There are a lot of details to naming these polycyclic alkanes. Here is the general idea:

    First, count the carbons. In this case, 10, so "decane."

    Second, count the number of distinct rings, in this case three, hence "tricyclo."

    Next, break the bond that will make the largest possible ring fragment while retaining the other rings. In this case it's one of the bonds in the cyclopropane ring. Breaking any of the bonds in the cyclopropane ring would give the same structure, so it doesn't matter which one.

    Next, look at the length of the ring fragments. By "ring fragments" I mean the number of atoms from one bridgehead carbon to another, not counting the bridgehead carbons. After the cyclopropane ring has been opened there will be two three-carbon ring fragments and one two carbon ring fragment. This is the origin of the first three numbers in the brackets.

    Finally, address the placement of the final ring. We know that this will be a "zero-atom" ring fragment (that gets us the zero in the brackets). To define the position of this zero-atom fragment, we must first number the carbons in the system. The numbering rules for polycycles state that you generally begin with one of the bridgehead carbons and then follow around the largest ring fragment to the the next bridghead, then around the next largest ring, etc. In this case you would follow around one of the 3 carbon ring fragments so that one bridgehead is carbon 1 and the other bridgehead is carbon 5. Then follow around the other three carbon fragment from carbon 5 until you get back to the other bridgehead (carbon 1). You should be at carbon 8 then. If you inspect this structure with the numbering you should find that the cyclopropane bond we broke was between carbons 2 and 8, so that is the origin of the superscript in the brackets. There is a zero-atom bridge between carbons 2 and 8.

    Incidentally, to complete the numbering of the polycycle you would follow around the 2 carbon fragment such that carbon 1 and carbon 9 bonded to one another and carbon 5 is bonded to carbon 10.

    Sheesh, I hope I got all of those rules right. I'm pretty sure that's the right name though.
  9. Jan 25, 2005 #8
    Thanks very much everyone who's replied!

    Sorry I put it in the wrong forum, but I did take it off a chemical engineering exam paper, so didn't really think about putting it under chemistry rather than chem. eng.
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