Organic Chemistry Functional Groups Overview

Overview

This lecture covers the most common organic chemistry functional groups, their structures, naming conventions, and key differences.

Hydrocarbons and Alkane Series

• Alkanes are hydrocarbons with only single carbon-hydrogen bonds (no double or triple bonds).
• The simplest alkanes: methane (1C), ethane (2C), propane (3C), butane (4C), pentane (5C), hexane (6C), heptane (7C), octane (8C), nonane (9C), decane (10C).

Alkenes, Alkynes, and Cycloalkanes

• Alkenes contain at least one carbon-carbon double bond (e.g., 2-butene).
• Alkynes contain at least one carbon-carbon triple bond (e.g., 2-butyne).
• Cycloalkanes are ring-shaped alkanes, named based on ring size (e.g., cyclopentane, cyclohexane).

Aromatics and Alkyl Halides

• Aromatic rings feature alternating double bonds; benzene is a common example.
• Alkyl halides (haloalkanes) consist of a hydrocarbon attached to a halogen (R-X).

Ethers and Alcohols

• Ethers have an oxygen atom between two alkyl groups (e.g., dimethyl ether).
• Alcohols contain an OH group on a carbon chain (e.g., 1-butanol, 2-butanol).

Carbonyl Compounds: Ketones and Aldehydes

• Ketones have a carbonyl group (C=O) within the chain (e.g., 2-pentanone).
• Aldehydes have a carbonyl group at the end of the chain (e.g., hexanal).

Carboxylic Acids, Esters, and Derivatives

• Carboxylic acids contain a COOH group (e.g., hexanoic acid).
• Esters have a COO group between two alkyl groups (e.g., methyl ethanoate).
• Acid anhydrides, acid chlorides (or bromides), and peroxy acids are related derivatives.

Amines, Amides, and Nitriles

• Amines have an NH2 group attached to a carbon chain (e.g., methylamine, ethylamine).
• Amides have a carbonyl group attached to an NH2 (e.g., butanamide).
• Nitriles have a carbon triple-bonded to nitrogen (e.g., ethanenitrile).

Sulfur-Containing and Special Functional Groups

• Thiols have an SH group (analogous to alcohols).
• Thioethers (R-S-R) and thioesters (analogous to ethers and esters, with sulfur).
• Enols (alkene + alcohol), enamines (alkene + amine), and imines (C=N).
• Peroxides (O-O single bond), organic peroxides, and peroxy acids.
• Nitro groups (NO2) are common in advanced organic chemistry.

Charged and Special Species

• Carbocations (positively charged carbon), carbanions (negatively charged carbon), radicals (odd number of electrons), and carbenes (neutral species).

Key Terms & Definitions

• Alkane — Saturated hydrocarbon with only single bonds.
• Alkene — Hydrocarbon with at least one double bond.
• Alkyne — Hydrocarbon with at least one triple bond.
• Cycloalkane — Ring-shaped alkane.
• Aromatic ring — Cyclic structure with alternating double bonds (e.g., benzene).
• Alkyl halide — Hydrocarbon attached to a halogen atom.
• Ether — Oxygen atom bonded to two alkyl groups.
• Alcohol — Hydrocarbon with an OH group.
• Ketone — Carbonyl group bonded within carbon chain.
• Aldehyde — Carbonyl group at the end of carbon chain.
• Carboxylic acid — Contains COOH group.
• Ester — COO group connecting two carbon chains.
• Amine — Contains an NH2 group.
• Amide — Carbonyl group attached to NH2.
• Nitrile — Carbon triple-bonded to nitrogen.
• Thiol — SH group attached to carbon.
• Thioether — Sulfur atom between two carbons.
• Thioester — Sulfur-containing ester.
• Enol — Molecule with both alkene and alcohol groups.
• Imine — C=N double bond.
• Nitro group — NO2 functional group.
• Peroxide — O-O single bond.
• Carbocation — Positively charged carbon species.
• Carbanion — Negatively charged carbon species.
• Radical — Species with unpaired electron.
• Carbene — Neutral carbon with two bonds and a lone pair.

Action Items / Next Steps

• Review and memorize the functional groups and their structures.
• Practice identifying and naming functional groups on sample molecules.
• Prepare for upcoming material on reactions involving these functional groups.