1. Chapter 17 Carboxylic Acids And Esters
Physical Properties of Carboxylic
Acids
Acidity of Carboxylic Acids

2. Carboxyl Group The carboxyl group:
Is a carbonyl group (C=O) attached to a hydroxyl group (OH).
Is found on carbon 1 in carboxylic acids.
Is written in different ways. O 
CH3—C—OH CH3—COOH CH3—CO2H

3. Models of Carboxylic Acids
The three-dimensional models show the geometry of atoms in carboxylic acid molecules.

4. IUPAC Names The IUPAC names of carboxylic acids:
Replace the -e in the alkane name with -oic acid.
CH4 methane HCOOH methanoic acid
CH3—CH3 ethane CH3—COOH ethanoic acid
Number substituents from the carboxyl carbon 1.
CH3 |
CH3—CH—CH2—COOH
3-methylbutanoic acid

5. Common Names The common names of simple carboxylic acids:
Use formic acid (1C), acetic acid (2C), propionic acid (3C), and butyric acid (4C).
HCOOH formic acid
CH3—COOH acetic acid
Locate substituents by assigning , , γ to the carbon atoms adjacent to the carboxyl carbon.
CH3
γ | 
CH3—CH—CH2—COOH
-methylbutryic acid

6. Names and Sources of Some Carboxylic Acids

7. Aromatic Carboxylic Acids
Benzoic acid:
Is the aromatic carboxylic acid.
Locates substituents by assigning 1 to the carbon attached to the carboxyl group.
Has common names that assign prefixes ortho, meta, and para for 2 substituents.
ortho 1, 2 location
meta 1, 3 location
para 1, 4 location

8. Aromatic Carboxylic Acids

9. Alpha Hydroxy Acids Alpha hydroxy acids (AHAs):
Occur naturally in fruit, milk, and sugarcane.
Are used in skin care products.

10. Preparation of Carboxylic Acids
Carboxylic acid can be prepared by oxidizing primary alcohols or aldehydes.
The oxidation of ethanol produces ethanoic acid (acetic acid).
OH O O
| [O] || [O] ||
CH3—CH CH3—C—H CH3—C—OH
Ethanol ethanal ethanoic acid
Ethyl alcohol acetaldehyde acetic acid

11. Boiling Points Carboxylic acids:
Have higher boiling points than alcohols, ketones, and aldehydes of similar mass.
Form dimers in which hydrogen bonds form between two carboxyl groups.
O H—O
|| |
CH3cC C—CH3
| ||
O—H O
A dimer of acetic acid

12. Solubility in Water Carboxylic acids:
With 1-4 carbon atoms are very soluble in water.
Form hydrogen bonds with many water molecules.

13. Boiling Points and Solubility

14. Acid Dissociation Constants
Carboxylic acids:
Are weak acids.
CH3—COOH + H2O
CH3—COO– + H3O+
Exist mostly as molecules and a few ions in aqueous solutions.
Have small Ka values.

15. Salts of Carboxylic Acids
Carboxylic acid salts are:
Formed when a carboxylic acid is neutralized by a strong base.
CH3—COOH + NaOH CH3—COO– Na+ + H2O
acetic acid sodium acetate
(carboxylic acid salt)
Used as preservatives and flavor enhancers.