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Homework Help: Organic nomenclature help

  1. Sep 24, 2009 #1
    1. The problem statement, all variables and given/known data
    Hello all.

    Im not sure how to get the image of the organic compound i need to name on here, but I think I can do a good job of describing it. The compound I need to name is a cycloheptane with three substituents on it. These substituents are bonded to three consecutive carbons. They are: a hydroxy group, a bromine, and an isopropyl (in that order going clockwise).

    3. The attempt at a solution
    The problem that im having is the order in which to name these substituents and the numbers to assign to them. Would it be bromine, isopropyl, and then hydroxy? ie does the isopropyl take priority alphabetically over the hydroxy group because of the Iso?

    Also, im confused as to what numbers to assign. Do i have to continue clockwise from the first substituent that I name (ie 1,2,7), or can i put something like 2,3,1?

  2. jcsd
  3. Sep 24, 2009 #2


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    Remember that functional groups can either be named as prefixes or suffixes. Generally, only one functional group gets to be named as a suffix (note: double- and triple-bonds are always named as suffixes in addition to the highest priority functional group). Which functional group gets named as a suffix depends on the priority (see http://en.wikipedia.org/wiki/IUPAC_nomenclature_of_organic_chemistry#Order_of_precedence_of_groups).

    In this case, both halogens and alkyl substituents are always named as prefixes, so the highest priority functional group is the alcohol. So, you get cycloheptanol as your base name. Now, you number the carbons in a way that the highest priority functional group gets the lowest number (in this case 1) and the next numbered substituent gets the lowest possible number.

    When writing the name, the prefixed substituents are listed in alphabetical order.
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