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Naming Cycloalkanes

  1. Feb 4, 2014 #1
    1. The problem statement, all variables and given/known data

    On the attachment is the answer to one of my questions written next to it as the instructor provided.
    But I am confused. I understand the first common naming answer, however the second, shouldnt it be 1 methyl, rather than 4,
    and then 4-(1-methylethyl)? Because with 2 substituents you label in alphabetical order. Am I missing some information that would allow me to label it as my instructor did?
    Please advise if you can.

    Thank you in advance.
     

    Attached Files:

  2. jcsd
  3. Feb 5, 2014 #2

    DrClaude

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    Staff: Mentor

    The methylethyl group is a chain of three carbon atoms, so it has precedence over the methyl with one carbon. Therefore, in terms of numbering, it is 1-(1-methylethyl) and 4-methyl. It is for the same reason that it is the isopropyl that gets numbered 1 (the numbering is independent of how you choose to name the group, isopropyl vs 1-methylethyl).

    Note that in the full name, alphabetic order is used:

    trans-1-isopropyl-4-methylcycloheptane

    trans-4-methyl-1-(1-methyethyl)cycloheptane
     
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