Overview
This lecture introduces and summarizes the main functional groups in organic chemistry, providing their structures, names, and key nomenclature rules.
Hydrocarbons
- Alkanes are hydrocarbons with only single C–C and C–H bonds (e.g., pentane: 5 carbons).
- Alkenes contain at least one C=C double bond (e.g., 2-butene: double bond between C2 and C3).
- Alkynes have a C≡C triple bond (e.g., 2-butyne).
- Cycloalkanes are ring-shaped alkanes with only single bonds (e.g., cyclopentane: 5 carbons, cyclohexane: 6 carbons).
- Aromatic rings feature alternating double bonds in a ring, such as benzene.
Halogenated Compounds
- Alkyl halides (haloalkanes) have a halogen atom (Cl, Br, F, I) attached to a hydrocarbon chain (general structure: R–X).
Oxygen-Containing Groups
- Ethers have an oxygen atom bonded to two hydrocarbon groups (R–O–R′); e.g., dimethyl ether.
- Alcohols contain an –OH (hydroxyl) group attached to an alkane (e.g., 1-butanol, 2-butanol).
- Ketones have a carbonyl group (C=O) within the carbon chain (general structure: R–CO–R′; e.g., 2-pentanone).
- Aldehydes have a carbonyl group at the end of the chain (R–CHO; e.g., hexanal).
Carboxylic Acid Derivatives
- Carboxylic acids feature a –COOH group (e.g., hexanoic acid).
- Esters have the structure R–COO–R′; named as alkyl alkanoate (e.g., methyl ethanoate).
- Amides have a carbonyl group attached to an NH2 group (R–CONH2; e.g., butanamide).
- Acid anhydrides contain two acyl groups joined by an oxygen atom (e.g., acetic anhydride).
- Acid chlorides have a –COCl group (e.g., acetyl chloride).
Nitrogen- and Sulfur-Containing Groups
- Amines have an –NH2 group attached to a carbon (e.g., methylamine, ethylamine).
- Nitriles contain a C≡N triple bond (e.g., ethanenitrile).
- Thiols have a –SH group, similar to alcohols but with sulfur.
- Thioethers have a sulfur atom bonded to two carbons (R–S–R′).
- Thioesters are esters with sulfur replacing the oxygen.
- Enols have a hydroxyl group adjacent to a double bond.
- Enamines have an amine group adjacent to a double bond.
- Imines feature a C=N double bond.
- Nitro groups are NO2 attached to carbon.
Peroxides and Related Groups
- Peroxides have two oxygens singly bonded (R–O–O–R′).
- Peroxy acids are carboxylic acids with a peroxide group (R–CO–OOH).
Other Important Species
- Carbocations are carbon atoms with a positive charge.
- Carbanions are carbon atoms with a negative charge.
- Radicals are species with unpaired electrons.
- Carbenes are neutral carbon species with two non-bonded electrons.
Key Terms & Definitions
- Alkane — hydrocarbon with only single bonds.
- Alkene — hydrocarbon with at least one C=C double bond.
- Alkyne — hydrocarbon with a C≡C triple bond.
- Aromatic ring — cyclic structure with alternating double bonds.
- Alcohol — molecule with an –OH group.
- Ketone — carbonyl group (C=O) within chain.
- Aldehyde — carbonyl group at chain end.
- Carboxylic acid — molecule with –COOH group.
- Ester — compound with R–COO–R′ structure.
- Amide — compound with R–CONH2 group.
- Nitrile — compound with C≡N group.
- Thiol — molecule with –SH group.
- Amine — molecule with –NH2 group.
- Peroxide — two oxygens joined by single bond.
Action Items / Next Steps
- Review functional group structures and practice naming sample compounds.
- Study similarities and differences between related groups (alcohols vs. thiols, ethers vs. thioethers, etc.).