Overview
This lecture reviews major organic functional groups, their structures, and key naming conventions relevant for organic chemistry exams.
Alkanes, Alkenes, and Alkynes
- Alkanes are hydrocarbons with only single C–C bonds (e.g., pentane has five carbons).
- Alkane names: methane (1 C), ethane (2 C), propane (3 C), butane (4 C), etc.
- Alkenes have at least one C=C double bond (e.g., 2-butene).
- Alkynes have at least one C≡C triple bond (e.g., 2-butyne).
Cyclic and Aromatic Compounds
- Cycloalkanes are ring alkanes with only single bonds (e.g., cyclopentane, cyclohexane).
- Aromatic rings have alternating double bonds; benzene is the basic example.
Halides, Ethers, and Alcohols
- Alkyl halides (haloalkanes) have halogen atoms (Cl, Br, F, I) attached to hydrocarbons.
- Ethers have an oxygen atom between two hydrocarbon groups (e.g., dimethyl ether).
- Alcohols contain an –OH group on a hydrocarbon (e.g., 1-butanol, 2-butanol).
Carbonyl Compounds: Ketones and Aldehydes
- Ketones have a carbonyl (C=O) group within the chain (e.g., 2-pentanone).
- Aldehydes have a carbonyl group at the end (e.g., hexanal).
Acids, Esters, and Related Groups
- Carboxylic acids (RCOOH) have a COOH group (e.g., hexanoic acid).
- Esters (RCOOR') have a C=O and an OR group (e.g., methyl ethanoate).
- Acid anhydrides have two acyl groups joined by an oxygen (e.g., acetic anhydride).
- Acid chlorides/bromides have a carbonyl attached to a halide (e.g., acetyl chloride).
Nitrogen and Sulfur-Containing Groups
- Amines (RNH2) have NH2 group(s) (e.g., methylamine, ethylamine).
- Amides (RCONH2) feature a carbonyl bonded to NH2 (e.g., butanamide).
- Nitriles (RCN) have a C≡N triple bond (e.g., ethanenitrile).
- Thiols (RSH) are sulfur analogs of alcohols.
- Thioethers (R–S–R') are sulfur analogs of ethers.
- Thioesters are sulfur analogs of esters.
Miscellaneous Functional Groups
- Enols contain an OH group on a carbon-carbon double bond.
- Enamines have an amine next to a double bond.
- Imines are compounds with a C=N double bond.
- Organic peroxides have two oxygens single-bonded together (e.g., H2O2 analogs).
- Peroxy acids combine carboxylic acid and peroxide structures.
- Nitro groups (NO2) are seen in nitro compounds.
Common Reactive Intermediates
- Carbocation: Positively charged carbon.
- Radical: Carbon with an unpaired electron.
- Carbanion: Negatively charged carbon.
- Carbene: Neutral carbon with two substituents and two non-bonding electrons.
Key Terms & Definitions
- Hydrocarbon — Molecule made only of hydrogen and carbon.
- Functional Group — Specific atom grouping giving characteristic reactions.
- Carbonyl group — C=O functional group.
- Aromatic ring — Cyclic structure with alternating double bonds.
- Suffixes: -ane (alkane), -ene (alkene), -yne (alkyne), -ol (alcohol), -al (aldehyde), -one (ketone), -oic acid (carboxylic acid), -amide (amide), -nitrile (nitrile), -ate (ester).
Action Items / Next Steps
- Memorize major functional groups and their general formulas.
- Practice naming examples for each group.
- Review structures and differences between similar groups (e.g., ketones vs. aldehydes).