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The suffix -oic acid is the IUPAC nomenclature used in organic chemistry to form names of carboxylic acids containing the acidic -(C)OOH group. It was extracted from the name of benzoic acid, which was named after benzoin resin, whose name probably came via Italian from Arabic lubān jāwī لُبَان جَاوِىّ = "frankincense from Java", because benzoin resin was brought from Indonesia.
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Description of Carboxylic Acids
Carboxylic acids are any organic compounds that contain a carbon to oxygen double bond with the same carbon also bonded to a hydroxyl group, often labeled as –COOH or as a carboxyl group. Carboxylic acids can be found all over in nature; from the bites of ants and wasps containing formic acid (HCOOH) to vinegar containing acetic acid (CH3COOH).
Properties of Carboxylic Acids
Carboxylic acids are capable of forming strong intermolecular bonds between two carboxylic acids by having two hydrogen bonds. These hydrogen bonds cause carboxylic acids to have higher boiling points. Carboxylic acid is the most acidic organic compound besides mineral acids because of the conjugate base of carboxylic acid is the carboxylate ion which is a weak base. With the conjugate base being weak, the original acid must then be strong because they are conjugate pairs. However, not all carboxylic acids have the same acidity and can vary greatly by the substituents added. For example, electron-withdrawing groups such as chlorine near the carboxyl group causes an inductive effect which increases the acidity of the molecule.
While electron-withdrawing groups increase the acidity of the molecule, electron-donating groups do the opposite and decreases the acidity.
General Carboxylic Acids
1. Identify the longest carbon chain where the #1 carbon includes the carboxyl group.
2. Name each substituent, with the location of the substituent labeled. (The number of the carbon that the substituent is on.) ex. 3-ethyl
Hydroxyl Substituent: "hydroxy"
Aldehyde/Ketone Substituent: "oxo"
Amino Substituent: "amino"
3. List the substituents in order alphabetically.
4. After the final substituent, name the carbon chain by the name of the number of carbons (1 carbon = meth-, 2 carbons = eth-, 3 carbons = prop-, 4 carbons = but-, 5 carbons = pent-, 6 carbons = hex-, 7 carbons = hept-, 8 carbons = oct-, 9 carbons = non-). Then add "an" for a saturated carbon chain and "en" for a carbon chain with a double bond. Finally, end with "-oic acid".
(Location of substituent-Name of substituent) + (Name of carbon chain)+("an" or "en")+("oic acid")
Carboxylic Acid Attached to Rings
1. Identify the number of carbons in the ring where the #1 carbon has the carboxyl group attached.
2. Name each substituent, with the location of the substituent labeled.
3. List the substituents in order alphabetically.
4. After the final substituent, name the ring by naming "cyclo" + carbon chain + "carboxylic acid".
(Location of substituent-Name of substituent) + ("Cyclo") + (Name of carbon chain) + ("Carboxylic Acid")
Carboxylic Acid Attached to Benzene
1. The #1 carbon has the carboxyl group attached.
2. Name each substituent, with the location of the substituent on the benzene labeled.
3. List the substituents in order alphabetically.
4. After the final substituent, name the ring by naming the substituents by #3 + benzoic acid if there is only one carboxyl group or benzene if there is two carboxyl groups + "carboxylic acid" for one carboxyl group or dicarboxylic acid for two carboxyl groups.
Carboxylates (-COO-)
1. Identify the longest carbon chain where the #1 carbon includes the carboxylate group.
2. Name each substituent, with the location of the substituent labeled. (The number of the carbon that the substituent is on.) ex. 3-ethyl
3. List the substituents in order alphabetically.
4. After the final substituent, name the carbon chain while replacing the "-e" with "oate".
Molecules containing two Carboxylic Acids
1. Identify the longest carbon chain where the #1 carbon includes a carboxyl group.
2. Name each substituent, with the location of the substituent labeled. (The number of the carbon that the substituent is on.) ex. 3-ethyl
Hydroxyl Substituent: "hydroxy"
Aldehyde/Ketone Substituent: "oxo"
Amino Substituent: "amino"
3. List the substituents in order alphabetically.
4. After the final substituent, name the carbon chain while replacing the "-e" with "-dioic acid".
(Location of Substituent-Name of substituent) + (Name of the carbon chain, replacing "-e" with "-dioic acid")
Naming by Common Names
Carboxylic acid common names are often older than their IUPAC names because they occur in biological sources. Their common names were given to them by the source that they came from. Carboxylic acids with up to ten carbons on their carbon chain all have common names. Since common names were decided based on the source of the compound, there isn’t a specific method to naming.