1. Carboxylic Acids & Esters

2. Topic Aims Level Method Equipment Duration
Chemistry- Intro Carboxylic Acids and Esters
Aims
To help introduce students to Carboxylic Acids and Esters Aimed at year olds
Level
Level 3
Method
In-depth PowerPoint slides, ALL can be hand-outs, some slides have questions and answers (could be done as a group discussion)
Equipment
Projector
Laptop
Pens
Hand-Outs
Duration
>30 Mins

3. Learning Outcomes 5th functional group – Carboxylic Acids
6th Functional Group - Esters
Drawing Carboxylic Acids & Esters
Naming Carboxylic Acids & Esters
Physical properties of Carboxylic Acids & Esters
Chemical properties of Carboxylic Acids & Esters

4. Carboxyl Group
Carboxylic acids contain the carboxyl group on carbon 1 O  CH3 — C—OH = CH3—COOH carboxyl group

5. Carboxyl Group

6. Naming Carboxylic Acids

7. Naming Carboxylic Acids
In the IUPAC names of carboxylic acids, the -e in the alkane name is replaced with -oic acid CH4 Methane HCOOH Methanoic acid CH3 - CH3 Ethane CH3 - COOH Ethanoic acid substituents are numbered from the carboxyl carbon 1 CH3 O CH3—CH—CH2—C—OH methylbutanoic acid

8. Common and IUPAC Names of Some Carboxylic Acids

9. Naming Carboxylic Acids
Give the IUPAC name for the
following carboxylic acid.
Step 1 Identify the carbon chain containing the carboxyl group and replace the -e in the alkane name with -oic acid.
Pentanoic acid
Step 2 Give the location and name of each substituent on the main chain by counting the carboxyl carbon as 1.
2-methylpentanoic acid

10. Aromatic Carboxylic Acids
Benzoic acid
is the simplest aromatic carboxylic acid
locates substituents by numbering the ring from carbon 1 in the carboxyl group

11. Learning Check CH3COOH CH3CH2COOH CH3CH2CH2COOH CH3 | CH3CHCOOH
ethanoic acid
propanoic acid
butanoic acid
2-methylpropanoic acid

12. Learning Check Give the IUPAC names of each compound. A. CH3CH2COOH
B CH3 |
CH3CHCH2COOH C.
propanoic acid
3-methylbutanoic acid
3-bromobenzoic acid

13. Polarity of Carboxylic Acids
Carboxylic acids are strongly polar because they have two polar groups hydroxyl (OH) and carbonyl (C=O)

14. Solubility in Water Carboxylic acids
form hydrogen bonds with many water molecules
with one to four carbon atoms are very soluble in water
as the number of carbons increases, the solubility of the carboxylic acid in water is reduced

15. Continue.....

16. Acidity of Carboxylic Acids
are weak acids
ionize in water to produce carboxylate ions and hydronium ions
can lose a proton because two oxygen atoms in carboxylate ion stabilize negative charge
O O
CH3COH + H2O CH3CO– + H3O+
carboxylic acid carboxylate ion

17. Neutralization of Carboxylic Acids
Carboxylic acid salts
are a product of the neutralization of a carboxylic acid with a strong base
CH3—COOH + NaOH CH3—COO– Na+ + H2O
acetic acid sodium acetate
(carboxylic acid salt)
are used as preservatives and flavor enhancers

18. Carboxylic acid salts
Carboxylic acid salts are used as preservatives and flavor enhancers such as
sodium propionate, which is used in cheese and breads
sodium benzoate, which inhibits growth of mold and bacteria and is added to fruit juices, margarine, relishes, salads, and jams
monosodium glutamate, MSG, which is added to meats, fish, vegetables, and baked goods to enhance flavor

19. Carboxylic Acid Salts Carboxylic acid salts
are ionic compounds with strong attractive forces between ions
are solids at room temperature
have high melting points
are usually soluble in water

20. Esters Esters are found in fats and oils
responsible for the aroma and flavor of bananas, oranges, and strawberries

21. Naming Esters
The name of an ester consists of two words derived from the name of the alcohol and the acid in that ester.
1. The first word indicates the alkyl part from the alcohol.
2. The second word is the carboxylate name of the carboxylic acid.

22. Naming Esters
Esters have IUPAC and common names:

23. Guide to Naming Esters

24. Guide to Naming Esters What is the IUPAC name of the following ester?
Step 1 Write the name of the carbon chain from the alcohol as an alkyl group.

25. Guide to Naming Esters continue….
Step 2 Change the -ic acid of the acid name to -ate.

26. Learning Check
Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears.
propyl ethanoate (IUPAC)
propyl acetate (common)

27. Learning Check Draw the structure of the following compounds.
3-bromobutanoic acid
ethyl propionoate

28. Aspirin and Salicylic Acid
is used to relieve pain and reduce inflammation
is an ester of salicylic acid and acetic acid
Oil of wintergreen
is used to soothe sore muscles
is an ester of salicylic acid and methanol

29. Esters in Fruits
Esters give pleasant fragrances and flavors to many fruits and flowers.

30. Esterification
Esterification is the reaction of a carboxylic acid and alcohol in the presence of an acid catalyst to produce an ester.
The main chain of an ester comes from the carboxylic acid, while the alkyl group in an ester comes from the alcohol.

31. Esterification
An example of esterification is the reaction of a ethanoic acid with 1-propanol to produce an ester called propylethanoate, responsible for the smell of pears.

32. Learning Check
Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst.

33. Acid Hydrolysis of Esters
In acid hydrolysis,
an ester reacts with water to produce a carboxylic acid and an alcohol
an acid catalyst is required

34. Base Hydrolysis (Saponification)
Base hydrolysis, or saponification,
is the reaction of an ester with a strong base
produces the salt of the carboxylic acid and an alcohol

35. Base Hydrolysis of Fatty Acids Produces Soaps

36. Cleaning Action of Soap
A soap
contains a nonpolar end that dissolves in nonpolar fats and oils, and a polar end that dissolves in water
forms groups of soap molecules called micelles that dissolve in water and are washed away

37. Learning Check
Write the organic products when methyl acetate reacts with A. water and an acid catalyst B. KOH

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