1. Functional Group Nomenclature
Organic Chemistry Lesson # 3

2. A reminder that a functional group is a group of atoms within a molecule that determine the properties of the molecule, such as solubility or reactivity.

3. 1. Alcohols
Alcohols contain the hydroxyl group –OH. To name, use the suffix “ol”.
If another functional group is present, such as an carbonyl or carboxyl (which we will discuss later), it is treated as a substituent and the prefix “hydroxy” is used.

4. Alcohols
The simplest alcohol, methanol, is used as an antifreeze and solvent. Ethanol is the most widely used alcohol, economically. It is the alcohol in beverages, but is also widely used as a fuel.
When the –OH group is on a terminal carbon, it is called a primary alcohol. If it is on a central carbon, a secondary or tertiary alcohol, depending on how many carbons are attached to the central atom. Each has slightly different properties.

5. Primary, Secondary, Tertiary Alcohols

6. Drawing Practice
a) hexan-3-ol
b) 2,4,6-trimethylheptan-1-ol

7. Drawing Practice
c) pentan-2,3-diol
d) benzene-1,2-diol

8. Drawing Practice
e) but-2-yne-1-ol f) cyclooctanol

9. Naming Practice

10. Naming Practice

11. Properties of Alcohols
Alcohols are polar as they contain an O-H hydrogen bond, and a C-O polar bond. This means that they have higher melting and boiling points than their corresponding alkanes.
Small alcohols tend to be much more soluble than alkanes in water, though as the number of carbons increases, the alcohols become less and less soluble as all the C-C and C-H bonds on one end of the molecule outweigh the single C-O and O-H bond. In this way, many larger alcohols are able to dissolve both polar and non-polar substances.

12. 2. Ethers
Ethers contain an oxygen atom bonded between two carbon atoms in a chain. To name, we use the word “oxy” between the two carbon chains.
Ethers are made from the synthesis of two alcohols, which we will discuss later.
The most common ether is ethoxyethane, which used to just be known as “ether” as was used as an anesthetic. It is quite volatile and flammable, so has been replaced with safer substances. It is now most commonly used as a solvent for fats and oils.

13. Drawing Practice
a) 1-ethoxyethane b) 2-methoxypropane

14. Drawing Practice
c) 3-ethoxypentane d) 3-propoxy-4-methylhexane

15. Naming Practice

16. Properties of Ethers
The boiling points of ethers tend to be slightly higher than their corresponding alkanes of the same carbon length, as they contain a C-O bond, but lower than alcohols.
When naming, we always name the shortest carbon chain first.
Ethers are useful solvents as their C-O bond allows them to dissolve polar molecules, and their C-C and C-H bonds allow them to dissolve less polar substances.

17. 3. Aldehydes and Ketones
Both aldehydes and ketones contain the carbonyl group –C=O.
When the bond to oxygen is on a terminal carbon it is called an aldehyde (use the suffix “al”), and on a central carbon it is called a ketone (use the suffix “one”).
Carbonyl compounds tend to have strong aromas, and are often found in spices, perfumes, and solvents. For example, propanone is also known as “acetone” and is the key ingredient in nail-polish remover.

18. Aldehyde vs. Ketone
Aldehyde Ketone

19. Drawing Practice
a) Propanal b) 3-methylpentanal

20. Drawing Practice
c) 2,4-dichloropentan-3-one d) 4-hydroxybutanal

21. Drawing Practice
e) cyclohexanone f) heptan-3,5-dione

22. Naming Practice

23. Naming Practice

24. Properties of Aldehydes and Ketones
The C=O polar bond of carbonyl compounds allows them to be polar, and so have higher boiling points than corresponding alkanes, but lower than alcohols.
Ketones are more polar than their corresponding aldehydes.
Similarly to alcohols, small carbonyls are completely soluble in water, while larger ones tend to be less soluble.

25. 4. Carboxylic Acids
A carboxylic acid contains a carboxyl group –COOH. This group makes these organic compounds weak acids (they do not dissociate completely in water).
To name, use the suffix “oic acid”. Carboxyl groups are always found on a terminal carbon.
Many citrus fruits contain carboxyl groups, and they are also used as preservatives.

26. Drawing Practice
a) propanoic acid b) benzoic acid c) 3-methylbutanoic acid

27. Naming Practice

28. Naming Practice

29. Properties of Carboxylic Acids
Carboxylic acids are very polar as they contain three polar bonds: -OH, C-O, and a C=O bond and so have very high melting and boiling points.
Small carboxylic acids (5 carbons or fewer) are soluble in water, and most carboxylic acids of any size are very soluble in polar organic solvents, like alcohols.
They also have many acidic properties, like changing the colour of indicators, and they react with bases to form water and ionic salts.

30. 5. Esters
An ester contains a carbonyl group, C=O and a C-O single bond on a central atom. It is formed from the combination of alcohols and carboxylic acids (more on this later).
Esters have very distinctive aromas and are often found in fruits or flowers.
Fats and oils are large ester molecules known as lipids. The structure of fats and oils is quite similar, though fats tend to be solid at room temperature, and oils are liquid.

31. Drawing & Naming Esters
To name, you must look at two parts – the part attached to the C-O is from the alcohol and is named as an alkyl group. The part attached to the C=O is from the acid and is named using the suffix “oate”.
a) pentyl butanoate
b) propyl ethanoate

32. Drawing Practice
c) methyl benzoate d) ethyl 3-methylbutanoate e) 2-methylbutyl ethanoate

33. Naming Practice

34. Naming Practice

35. Naming Practice

36. Properties of Esters
Since esters have C-O and C=O bonds they are polar, but less polar than carboxylic acids as they contain no hydroxyl group. This means they have slightly lower boiling points and are less soluble than their corresponding acids.
Small esters are gas at room temperature whereas heavier ones are waxy solids.

37. 6. Amines
An amine is when nitrogen is attached to a carbon chain. It is derived from ammonia when one of the hydrogens is replaced with an alkyl group. It is called an amino group –NH.
Amines are basic molecules, so can be neutralized by acids.
Amines have an unpleasant fishy odour, or they smell like ammonia. They are formed from the breakdown of proteins.

38. Amines
Like alcohols, an amine can be primary, secondary, or tertiary depending on its location in the alkyl chain.
To name, we use the suffix “amine” and use the letter N if the amino group is between two carbon chains.
Primary
Secondary
Tertiary

39. Drawing Practice
a) propan-1-amine b) N-ethyl-pentan-2-amine

40. Drawing Practice
c) hexan-1,4-diamine d) N,N-dimethylbutan-2-amine

41. Drawing Practice
e) N-ethyl-N-methylheptan-3-amine f) N-ethyl-N-propylhexan-3-amine

42. Naming Practice

43. Naming Practice

44. Properties of Amines
Amines contain C-N polar bonds and sometimes N-H hydrogen bonds, which means they are quite polar, have higher boiling points than their corresponding alkanes.
Small amines are soluble in water, though their solubility decreases with carbon chain length.

45. 7. Amides
An amide is a hydrocarbon formed from a carbonyl and a nitrogen atom. It is formed from the synthesis of amines with carboxylic acids (more on this later).
Amides are commonly used as solvents, but also have uses in polymers, and even pharmaceuticals such as acetaminophen (Tylenol).
To name, like esters, you must look at the two parts. The part attached to the nitrogen is named first as an alkyl group, and the part attached to the carbonyl group is named with the suffix “amide” last.

46. Drawing Practice
a) N-methylbutanamide b) N-ethylpropanamide

47. Drawing Practice
c) N,N-dimethylethanamide d) N-propyl-2-methylpentanamide

48. Drawing Practice
e) N-ethyl-2-bromoethanamide f) N-chloromethylpropanamide

49. Naming Practice

50. Naming Practice

51. Properties of Amides
Amides are very polar. They have C=O, C-N, and some have N-H bonds. They tend to be more polar than their corresponding amines, which leads to higher boiling points and greater solubility.
Primary amides are more soluble and have higher melting points than secondary amides, due to their N-H bonds.
Polarity Summary
Amide > Acid > Alcohol > Ketone > Aldehyde > Amine > Ester > Ether > Alkane

52. Summary Functional Group Naming Alcohol
Ends in –ol, use hydroxy- when is a substituent when other groups are present
Ether
-oxy between alkyl chains
Aldehyde
Ends in -al
Ketone
Ends in -one
Carboxylic Acid
Ends in –oic acid
Ester
Ends in –oate, alcohol part first, followed by acid
Amine
Ends in –amine, use N for 2° and 3°
Amide
Ends in –amide, use N, amine part first, followed by acid