Functional Groups in Organic Chemistry

Overview

• Functional Groups: Specific groups of atoms within molecules that determine the chemical reactions of those molecules.
• R group: Placeholder for the rest of the molecule that isn’t the focus of the discussion.

Carbon Chains

• Alkane: Single bonds between carbons, sp3 hybridized, 109.5° bond angles, zigzag structure.
• Alkene: At least one double bond between carbons, sp2 hybridized, 120° bond angles.
• Alkyne: At least one triple bond between carbons, sp hybridized, 180° bond angles.

Key Functional Groups

Alkyl Halide / Haloalkane

• Halogens (Fluorine, Chlorine, Bromine, Iodine) attached to a carbon chain.
• Primary, Secondary, Tertiary: Based on the number of carbons attached to the carbon bearing the halogen.

Amines

• Nitrogen atom bound to 1-4 carbons.
• Primary, Secondary, Tertiary, Quaternary: Based on the number of carbons attached to the nitrogen atom.

Alcohols (COH)

• OH group (Hydroxyl) attached to a carbon chain.
• Primary, Secondary, Tertiary: Based on the carbon bearing the OH group.

Thiols

• SH group: Sulfur replacing oxygen in alcohols.

Ethers (ROR)

• Oxygen between two carbon groups.
• Symmetrical or Asymmetrical: Depending on whether the carbon groups are the same or different.
• Cyclic Ethers: Oxygen in a carbon ring (e.g., THF).
• Epoxides: Three-membered ring ethers (two carbons, one oxygen).

Carbonyl-Containing Groups

Ketones

• Carbonyl (C=O) in the middle of the chain.
• Symmetrical or asymmetrical.

Aldehydes

• Carbonyl (C=O) at the end of the chain, followed by a hydrogen.

Carboxylic Acids

• Carbonyl (C=O) and OH at the end of the chain.

Esters

• Carbonyl (C=O) and OR (where R is an alkyl group).

Amides

• Carbonyl (C=O) and Nitrogen.
• Similar to amines, but with a carbonyl group.

Nitriles (RC≡N)

• Carbon triple-bonded to Nitrogen.

Phenol vs. Phenyl

• Phenol: Benzene ring with an alcohol (OH).
• Phenyl: Benzene ring as a substituent in a larger molecule.

Study Tips

• Use mnemonics to memorize different types of functional groups.
• Practice identifying and naming functional groups using online quizzes and resources.

Resources

• Visit leah4sci.com/Naming to download a full-color functional group cheat sheet and practice quiz for further study.