Organic Chemistry Functional Groups: Structure and Reactions

Alcohols, Thiols, Ethers, Aldehydes, and Ketones

1. Identifying Functional Groups

• Alcohol: -OH group attached to a carbon atom.
• Phenol: -OH group attached directly to a benzene ring.
• Thiol: -SH group (sulfhydryl group).
• Ether: C-O-C linkage (oxygen atom bonded to two carbon groups).
• Aldehyde: -CHO group (carbonyl group at the end of a chain).
• Ketone: C=O group (carbonyl group) located in the middle of a chain.

2. Naming Conventions (Nomenclature)

• Alcohol: Replace the alkane suffix “-e” with “-ol” (e.g., ethanol).
• Phenol: Named as phenol, often requiring position numbers.
• Thiol: Use the suffix “-thiol”.
• Ether: Name both alkyl or aryl groups, followed by the word “ether”.
• Aldehyde: Use the suffix “-al”.
• Ketone: Use the suffix “-one”.

3. Classifying Alcohols

• Primary (1°): OH on carbon attached to one other carbon atom.
• Secondary (2°): OH on carbon attached to two other carbon atoms.
• Tertiary (3°): OH on carbon attached to three other carbon atoms.

4. Properties of Functional Groups

• Alcohols: Polar; form strong hydrogen bonds, resulting in high boiling points.
• Ethers: Lower boiling points compared to alcohols of similar mass.
• Thiols: Characteristically smelly; slightly polar.
• Aldehydes/Ketones: Polar; exhibit moderate boiling points.

5. Oxidation and Reduction Definitions

• Oxidation: Gain of oxygen atoms or loss of hydrogen atoms.
• Reduction: Loss of oxygen atoms or gain of hydrogen atoms.

6. Alcohol Reactions

Alcohol Oxidation and Other Reactions

• Combustion: Alcohol + O₂ → CO₂ + H₂O
• Dehydration: Alcohol → Alkene + H₂O (loss of water).
• Oxidation Pathways:
  • 1° alcohol → aldehyde → carboxylic acid
  • 2° alcohol → ketone

7. Aldehyde and Ketone Oxidation

• Aldehyde: Oxidizes easily to a Carboxylic acid.
• Ketones: Do not oxidize easily under typical conditions.

Carboxylic Acids, Esters, Amines, and Amides

1. Identifying Functional Groups

• Carboxylic Acid: -COOH (carboxyl group).
• Ester: -COOR (R is an alkyl or aryl group).
• Amine: Derivatives of ammonia: -NH₂, -NHR, or -NR₂.
• Amide: -CONH₂ or variations where H atoms are replaced by R groups.

2. Naming Conventions (Nomenclature)

• Carboxylic Acids: Use the suffix “-oic acid”.
• Esters: Named using the alcohol part first, followed by the acid part (e.g., ethyl ethanoate).
• Amines: Use the suffix “-amine” or the prefix “amino-”.
• Amides: Use the suffix “-amide”.

3. Properties of Functional Groups

• Carboxylic Acids: Sour taste; acidic; strong hydrogen bonding.
• Esters: Often smell sweet (fruity); lack intermolecular hydrogen bonding.
• Amines: Basic; often have a characteristic fishy odor.
• Amides: Neutral; exhibit strong hydrogen bonding.

4. Carboxylic Acid Reactions

• Ionization: Acid → carboxylate ion + H⁺
• Neutralization: Acid + base → salt + water

5. Esterification Reaction

The formation of an ester:

Carboxylic acid + alcohol → Ester + water

6. Hydrolysis of Esters

Breaking Down Esters

• Acid Hydrolysis: Ester + water → Carboxylic acid + alcohol (reversible).
• Base Hydrolysis (Saponification): Ester + base → Carboxylate salt + alcohol.

7. Classifying Amines

• Primary (1°): Nitrogen atom bonded to one carbon group.
• Secondary (2°): Nitrogen atom bonded to two carbon groups.
• Tertiary (3°): Nitrogen atom bonded to three carbon groups.

8. Amine Reactions

• Ionization (Basicity): Amine + H₂O → Ammonium ion + OH⁻
• Neutralization: Amine + acid → Ammonium salt