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Homework Help: Organic Naming

  1. Mar 26, 2009 #1
    1. The problem statement, all variables and given/known data
    Name each of the following cyclic alkanes, and indicate the formula of the compound.
    http://img230.imageshack.us/img230/1042/organicnaming.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution
    a. The rectangle has four corners so four carbon for butane. The branch off has two carbons so eth-. Numbering the branch C as 1, the naming is 1-ethylcyclobutane with C6H12 because each corner is 1 C plus the C written and the H comes from subtracting 4 with the number of bonds connected to each of the C. Is this correct?

    b. The pentagon has five corners so five corner for pentane. The branch off is prop- and meth-. Naming starts with alphabetical order so meth- first so the prop- is three. 1-methyl-3-propylcyclopentane. Logic from a., C9H18. Is this correct?

    c. Hexane from six corners. Dimethyl and ethyl here. Is this named 1-ethyl-2,6-dimethylcyclohexane or 2-ethyl-1,3-dimethylcyclohexane? C10H20.

    If there is a mistake, which part?
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 27, 2009 #2
    A is just ethylcyclobutane. There is no need to number the substituent, since a cycloalkane with 1 substituent will always have it at the #1 carbon. You had the formula right.

    B is correct.

    C is 2-ethyl-1,3-dimethylcyclohexane (you number so as to give your substituents the lowest number possible, in the absence of priority substituents such as OH). Formula is correct.
    Last edited by a moderator: May 4, 2017
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