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21.1 Naming Carboxylic Acid Derivatives

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  • Page ID
    90992
  • Objectives

    After completing this section, you should be able to

    1. provide a satisfactory name for an acid halide of given structure.
    2. draw the condensed or shorthand structure of an acid halide, given either its commonly used or systematic name.
    3. provide a satisfactory name for an acid anhydride of given structure.
    4. draw the condensed or shorthand structure of an acid anhydride, given either its trivial or IUPAC name.
    5. provide an acceptable name for an amide of given structure.
    6. draw the condensed or shorthand structure of an amide, given its trivial or IUPAC name.
    7. provide an acceptable name for an ester of given structure.
    8. draw the condensed or shorthand structure of an ester, given either its trivial or IUPAC name.
    9. provide an acceptable name for a thioester of given structure.
    10. draw the condensed or shorthand structure of a thioester, given its trivial or IUPAC name.
    11. provide an acceptable name for an acyl phosphate.
    12. draw the condensed or shorthand structure of an acyl phosphate, given either its trivial or IUPAC name.

    Nomenclature of acid halides

    The nomenclature of acid halides starts with the name of the corresponding carboxylic acid. The –ic acid ending is removed and replaced with the ending -yl followed by the name of the halogen with an –ide ending. This is true for both common and IUPAC nomenclature. The carbonyl carbon is given the #1 location number. It is not necessary to include the location number in the name because it is assumed that the functional group will be on the end of the parent chain.

    Example 21.1.1

    Nomen2.jpg

    The acid anhydride functional group results when two carboxylic acids combine and lose water (anhydride = without water). Symmetrical acid anhydrides are named like carboxylic acids except the ending -acid is replaced with -anhydride. This is true for both the IUPAC and Common nomenclature.

    Nomenclature of Anhydrides

    Symmetrical anhydrides

    A symmetrical anhydride is a carboxylic acid anhydride that has the following general structural formula.

    where R1=R2= hydrogen atoms, alkyl groups, aryl groups

    Nomen1.jpg

    Unsymmetrical Anhydrides

    A mixed or unsymmetrical anhydride is a carboxylic acid anhydride that has the following general structural formula.

    where R1≠R2, but are hydrogen atoms, alkyl groups, aryl groups. When naming unsymmetrical acid anhydrides, name both using alkanoic general method and then put the two names alphabetically. Hence, first name each component and alphabetically arranged them followed by spaces and then the word anhydride.

    Nomen2.jpg

     

    propanoic anhydride

    ethanoic propanoic anhydride

    Exercise

    Try to name the following compound

    J

    Try to draw a structure for the following compound�

    • 1,2-benzenedicarboxylic anhydride J

    Common names that you should know

    acetic anhydride (Try to name this anhydride by the proper name. J )

    succinic anhydride (Try to name this anhydride by the proper name. J )

    Nomenclature of Esters

    Esters are made from a carboxylic acid and an alcohol.

     

    Esters are named as if the alkyl chain from the alcohol is a substituent. No number is assigned to this alkyl chain. This is followed by the name of the parent chain form the carboxylic acid part of the ester with an –e remove and replaced with the ending –oate.

    Example 21.1.2

    Ester2.jpg

    Nomenclature of Thioesters

    Thiosters are made from a carboxylic acid and an thiol.

     

    Thioesters are named as if the alkyl chain from the alcohol is a substituent. No number is assigned to this alkyl chain. This is followed by the name of the parent chain from the carboxylic acid part of the thioester named as an alkane with the ending –thiooate.

    Example 21.1.3


     

    Nomenclature of amides

    Primary amides

    Primary amides are named by changing the name of the acid by dropping the -oic acid or -ic acid endings and adding -amide. The carbonyl carbon is given the #1 location number.  It is not necessary to include the location number in the name because it is assumed that the functional group will be on the end of the parent chain.

           

    methanamide or formamide (left), ethanamide or acetamide (center) , benzamide (right)

     

    Amide1.jpg

     

    Exercise

    Try to draw a structure for the following compound

    •  3-chlorobenzamide J

    Try to name the following compound

       J

    Secondary amides

    Secondary amides are named by using an upper case N to designate that the alkyl group is on the nitrogen atom. Alkyl groups attached to the nitrogen are named as substituents.  The letter N is used to indicate they are attached to the nitrogen. Tertiary amides are named in the same way. 

     

    N-methylpropanamide

     

    Amide2.jpg

    Exercise

    1. Try to draw a structure for N,N-dimethylformamide J
    2. Try to name the following compound

     J

    Name the parent alkane (include the carbon atom of the nitrile as part of the parent) followed with the word -nitrile. The carbon in the nitrile is given the #1 location position. It is not necessary to include the location number in the name because it is assumed that the functional group will be on the end of the parent chain.

    Naming Phosphates

    Phosphoryl groups are derivatives of phosphoric acid, a strong acid that is commonly used in the laboratory. The fully deprotonated conjugate base of phosphoric acid is called a phosphate ion, or inorganic phosphate (often abbreviated 'Pi'). When two phosphate groups are linked to each other, the linkage is referred to as a  'phosphate anhydride', and the ion is called 'inorganic pyrophosphate' (abbreviation PPi).

    image002.png

    When a phosphate ion is attached to a carbon atom on an organic molecule, the chemical linkage is referred to as a phosphate ester, and the whole species is called an organic monophosphate. Glucose-6-phosphate is an example.

    image004.png

    If an organic molecule is linked to two or three phosphate groups, the resulting species are called organic diphosphates and organic triphosphates.

    image006.png

    Isopententyl diphosphate and adenosine triphosphate (ATP) are good examples:

    image008.png

    Oxygen atoms in phosphate groups are referred to either 'bridging' and 'non-bridging', depending on their position. An organic diphosphate has two bridging and five non-bridging oxygens.

    image010.png

    When a single phosphate is linked to two organic groups,  the term 'phosphate diester' is used. The backbone of DNA is composed of phosphate diesters.

    image012.png

    The term 'phosphoryl group' is a general way to refer to all of the phosphate-based groups mentioned in the paragraphs above.

    Recall (section 1.4A) that phosphate groups on organic structures are sometimes abbreviated simply as 'P', a convention that we will use throughout this text.  For example, glucose-6-phosphate and isopentenyl diphosphate are often depicted as shown below. Notice that the 'P' abbreviation includes the oxygen atoms and negative charges associated with the phosphate groups.

    image014.png

    Exercises

    Questions

    Q21.1.1

    Name the following compounds using IUPAC conventions

    (a)

     

    (b)

     

    (c)

     

    (d)

     

    (e)

     

    (f)

     

    (g)

     

    (h)

     

    (i)

     

    Solutions

    S21.1.1

    1. 3-methylpentanoyl chloride
    2. 2-cyclopentylacetamide
    3. propyl 2-methylpropanoate
    4. cyclohexylbutanoate
    5. tert-butyl cyclopentanecarboxylate
    6. 1-methylbutylcyclopentane carboxylate
    7. N-methyl-3-butenamide
    8. (S)-2-hydroxypropanoyl phosphate
    9. propyl 2,3-dimethyl-2-butenethioate

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