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18.2: Functional Group Order of Precedence For Organic Nomenclature

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    216695
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    In the IUPAC nomenclature system, organic molecules are grouped into specific classes of compounds determined by the main functional group present in the structure. A system of priorities is used to determine the main functional group, which determines the identity of the compound. All other functional groups are treated as substituents. The following order of precedence refers to functional groups containing carbon as the central atom. As a rule of thumb, the higher the oxidation state of the central carbon, the higher the priority of the functional group. Thus, carboxylic acids have higher priority than alcohols, and so on (See also table 21-1 in your textbook).

    1. CARBOXYLIC ACIDS (highest priority among carbon-containing functional groups).

    clipboard_e758946e12409999612ff65d0b812ca26.png

     

    2. CARBOXYLIC ACID DERIVATIVES

    clipboard_ecd8629c1319f42e0543b33ce1a2d5bc0.png

     

    3. OTHER GROUPS CONTAINING OXYGEN OR NITROGEN

    clipboard_ee399de093ef9300a53d324a380d7128e.png

    4. ALKENES AND ALKYNES

    clipboard_e7f304a967b8baf3ed82fcf5d8ce501e8.png

    Note: substances containing double and triple bonds are called alkenynes. (notice that the name ends in yne). Chain numbering starts from the end closest to either group, unless they’re both equidistant from the chain ends, in which case the double bond takes priority and is given the lower number. See examples in the textbook.

     

    5. LOWEST PRIORITY. These groups are usually considered substituents in the main chain.

    clipboard_ebaa0bfcfdb37880687e13e72b14f0186.png


    This page titled 18.2: Functional Group Order of Precedence For Organic Nomenclature is shared under a not declared license and was authored, remixed, and/or curated by Sergio Cortes.

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