1. Carboxylic Acids and Esters,
Properties of Carboxylic Acids
Esters
Esterification and Hydrolysis

2. Carboxyl Group
Carboxylic acids contain the carboxyl group on carbon 1. It will be the first carbon of the parent chain. O 
CH3 — C—OH = CH3—COOH
carboxyl group

3. Naming Carboxylic Acids
Formula IUPAC Common
alkan -oic acid prefix – ic acid
HCOOH methanoic acid formic acid
CH3COOH ethanoic acid acetic acid
CH3CH2COOH propanoic acid propionic acid
CH3CH2CH2COOH butanoic acid butyric acid

4. Naming Rules Identify longest chain
(IUPAC) Number carboxyl carbon as 1
Name side chains alphabetically
CH3 |
CH3 — CH—CH2 —COOH
IUPAC methylbutanoic acid

5. Naming Practice Give IUPAC and common names: A. CH3COOH CH3 |
B. CH3CHCOOH

6. Solution A. CH3COOH ethanoic acid; acetic acid CH3 | B. CH3CHCOOH
2-methylpropanoic acid

7. Draw the Structures
3-methyl-4-phenylhexanoic acid
pentanedioic acid

8. Properties CH3COOH + H2O CH3COO– + H3O+ Neutralized by a base
Carboxylic acids are weak acids. They can be found in citrus fruits and others with a sour taste. Vitamin C and ASA are other common carboxylic acids.
CH3COOH + H2O CH3COO– + H3O+
Neutralized by a base
CH3COOH + NaOH CH3COO– Na+ + H2O

9. Properties
The carboxyl groups consists of a polar hydroxyl group bonded to the carbon of a carbonyl group. The presence of the polar carbonyl and polar hydroxyl groups makes carboxylic acids able to hydrogen bond with themselves and water.
The smallest members (carbons 1-4) are soluble in water. As the alkyl group (CH) becomes longer, the polarity of the molecule decreases as does the solubility in water.
Melting point increases with the size of the molecule. Analogous acids with multiple carboxyl groups have higher melting points.

10. Learning Check Compare the melting point and solubility in water of:
1-butanol
butanal
butane
butanoic acid

11. Solution Lowest to highest melting point and solubility:
Butane (nonpolar, LDF only)
Butanal (polar, LDF, DDF, no hydrogen bonding with self )
1-Butanol (polar, LDF, DDF, hydrogen bonding with self and water)
Butanoic Acid (most polar functional group, LDF, DDF, hydrogen bonding with self and water)

12. Reactions of Carboxylic Acids
Oxidation of a Primary Alcohol to Aldehyde
Further Oxidation to a Carboxylic Acid
*Ketones are not oxidized further

13. Esters
In and ester, the H in the carboxyl group is replaced with an alkyl group (COO) O 
CH3 — C—O —CH3 = CH3—COO —CH3
ester group

14. Esters in Plants
Esters give flowers and fruits their pleasant fragances and flavours.

15. Naming Esters Name the alkyl from the alcohol –O-
Name the acid with the C=O with –ate (drop “ic” from acid name and and “ate)
acid alcohol O
 methyl
CH3 — C—O —CH3
Ethanoate methyl ethanoate (IUPAC)
(acetate) methyl acetate (common)

16. Some Esters and Their Names
Flavor/Odour
Raspberries
HCOOCH2CH3 ethyl methanoate (IUPAC)
ethyl formate (common)
Pineapples
CH3CH2CH2 COOCH2CH3
ethyl butanoate (IUPAC)
ethyl butyrate (common)

17. Practice
Give the IUPAC and common names of the following compound, which is responsible for the flavor and odour of pears. O 
CH3 — C—O —CH2CH2CH3

18. Solution O ethanoic acid  propyl (propanol) CH3 — C—O —CH2CH2CH3
propyl ethanoate (IUPAC)
propyl acetate (common)

19. Practice
Draw the structure of the following compounds and name the alcohol and acid used to synthesize the ester:
3-bromobutanoic acid
Ethyl propanoate

20. Solution CA 3 A. 3-bromobutanoic acid Br | CH3CHCH2COOH
B. Ethyl propanoate (ethanol and propanoic acid) O 
CH3 CH2 COCH2CH3 CH3CH2COOCH2CH3

21. Esterification O Reaction of a carboxylic acid and alcohol
Acid catalyst and heat O
 H+
CH3 — C—OH + HO—CH2CH3 
CH3 — C—O—CH2CH H2O

22. Ester Practice
Illustrate the reaction between the acids and alcohols listed and name the ester
(i) 3-methylbutanoic acid and methanol
(ii) benzoic acid and ethanol

23. Solution
(i)
(ii)

24. Hydrolysis O Esters react with water and acid catalyst
Split into carboxylic acid and alcohol O
 H+
H — C—O—CH2CH H2O 
H — C—OH + HO—CH2CH3

25. Saponification Esters react with a bases
Produce the salt of the carboxylic acid and alcohol O 
CH3C—OCH2CH NaOH
CH3C—O– Na HOCH2CH3
salt of carboxylic acid

26. More Practice
Write the equation for the reaction of pentanol and 3-chlorobutanoic acid in the presence of an acid catalyst.

27. Solution

28. Reaction Practice
What are the organic products when methylacetate (ethanoate) reacts with
A. Water and an acid catalyst?
B. KOH?

29. Solution A. O 
CH3COH HOCH3
B. CH3CO– K HOCH3

30. POLYESTERS Esters can form long chain polymers called polyesters.
Examples

31. Properties of Esters
The loss of the polar OH group in the esterification rxn results in esters being less polar, less soluble in water than their parent carboxylic acids and alcohols.
Lower mass esters are detected by scents because they are gases at room temperature. Larger, heavier esters tend to be waxy solids.