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1.10: Carboxylic acids and Esters

  • Page ID
    222814
  • Learning Objective

    • How to name carboxylic acids and esters.

    A carbonyl group consists of a carbon atom double-bonded to an oxygen atom, written as C=O. When a hydroxy (-OH) group is also bound to the carbonyl carbon, the resulting group is known as a carboxy group. Carboxylic acids contain the carboxy group, and one type of carboxylic acid derivative is an ester.

    Figure \(\PageIndex{1}\).svg
    Figure \(\PageIndex{1}\): carboxylic acid
    Figure \(\PageIndex{2}\).svg
    Figure \(\PageIndex{2}\): ester

    Carboxylic acids are often abbreviated as R-COOH or R-CO2H. Some simple carboxylic acids, such as acetic acid and benzoic acid, are referred to primarily by their common names.

    Figure \(\PageIndex{3}\).svg
    Figure \(\PageIndex{3}\): acetic acid and benzoic acid

    The common name of this molecule is valeric acid. Its formal name is pentanoic acid.

    Figure \(\PageIndex{4}\).svg
    Figure \(\PageIndex{4}\): pentanoic acid

    Practice Questions

    1. The common name of Molecule A is caprylic acid. What is the formal name of Molecule A?

    Figure \(\PageIndex{5}\).svg
    Figure \(\PageIndex{5}\): Molecule A

    2. The name of this molecule is hexanedioic acid.

    Figure \(\PageIndex{6}\).svg
    Figure \(\PageIndex{6}\): hexanedioic acid

    What is the name of Molecule B?

    Figure \(\PageIndex{7}\).svg
    Figure \(\PageIndex{7}\): Molecule B

    3. The name of this molecule is cyclohexanecarboxylic acid.

    Figure \(\PageIndex{8}\).svg
    Figure \(\PageIndex{8}\): cyclohexanecarboxylic acid

    What is the name of Molecule C?

    Figure \(\PageIndex{9}\).svg
    Figure \(\PageIndex{9}\): Molecule C

    4. The name of this molecule is 1,2-benzenedicarboxylic acid.

    Figure \(\PageIndex{10}\).svg
    Figure \(\PageIndex{10}\): 1,2-benzenedicarboxylic acid

    What is the name of Molecule D?

    Figure \(\PageIndex{11}\).svg
    Figure \(\PageIndex{11}\): Molecule D

    5. The name of this molecule is 4-bromopentanoic acid. Number the carbons.

    Figure \(\PageIndex{12}\).svg
    Figure \(\PageIndex{12}\): 4-bromopentanoic acid

    6. Number the carbons. What is the name of Molecule E?

    Molecule E

    Figure \(\PageIndex{13}\).svg

    Figure \(\PageIndex{13}\).

    7. This molecule is named 2-hydroxybutanoic acid (also known as lactic acid).

    Figure \(\PageIndex{14}\).svg
    Figure \(\PageIndex{14}\): 2-hydroxybutanoic acid

    What is the name of Molecule F?

    Figure \(\PageIndex{15}\).svg
    Figure \(\PageIndex{15}\): Molecule F

    8. This molecule is named 3,6-dioxo-4-hydroxyhexanoic acid.

    Figure \(\PageIndex{16}\).svg
    Figure \(\PageIndex{16}\): 3,6-dioxo-4-hydroxyhexanoic acid

    What is the name of Molecule G?

    Figure \(\PageIndex{17}\).svg
    Figure \(\PageIndex{17}\): Molecule G

    Esters are often manufactured to provide fragrance. One example is isobutyl methanoate, which smells like raspberries.

    Figure \(\PageIndex{18}\).svg
    Figure \(\PageIndex{18}\): isobutyl methanoate

    The process of esterification involves adding an alcohol to a carboxylic acid in the presence of hydrogen ions.

    Figure \(\PageIndex{19}\).svg
    Figure \(\PageIndex{19}\): esterification

    To name an ester, first we name the alcohol used, and then the carboxylic acid. Below is shown the esterification reaction of ethanol and propanoic acid to create ethyl propanoate.

    Figure \(\PageIndex{20}\).svg
    Figure \(\PageIndex{20}\): synthesis of ethyl propanoate

    Practice Questions

    1. What is the name of Molecule H?

    Figure \(\PageIndex{21}\).svg
    Figure \(\PageIndex{21}\): Molecule H

    2. What is the name of Molecule I?

    Figure \(\PageIndex{22}\).svg
    Figure \(\PageIndex{22}\): Molecule I

    3. This molecule is named dimethylbutanedioate.

    Figure \(\PageIndex{23}\).svg
    Figure \(\PageIndex{23}\): dimethylbutanedioate

    What is the name of Molecule J?

    Figure \(\PageIndex{24}\).svg
    Figure \(\PageIndex{24}\): Molecule J

    4. This molecule is named 2-chloroethyl propanoate.

    Figure \(\PageIndex{25}\).svg
    Figure \(\PageIndex{25}\): 2-chloroethyl propanoate

    What is the name of Molecule K?

    Figure \(\PageIndex{26}\).svg
    Figure \(\PageIndex{26}\): Molecule K

    5. This molecule is named 2-bromopropyl 4-chlorobutanoate. Number the carbons.

    Figure \(\PageIndex{27}\).svg
    Figure \(\PageIndex{27}\): 2-bromopropyl 4-chlorobutanoate

    6. Number the carbons. What is the name of Molecule L?

    Figure \(\PageIndex{28}\).svg
    Figure \(\PageIndex{28}\): Molecule L

    7. What additions do we make to our existing naming rules to name carboxylic acids and esters?

    8. Write the steps that you use to name a carboxylic acid in order, as instructions for a student who doesn't know how to do it.

    9. Draw any carboxylic acid and go through the steps in naming your molecule.

    10. Write the steps that you use to name an ester in order, as instructions for a student who doesn't know how to do it.

    11. Draw any ester and go through the steps in naming your molecule.

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