Overview
This lecture discusses in detail the types, nomenclature, preparation methods, and main physical properties of haloalkanes and haloarenes.
Introduction to Haloalkanes and Haloarenes
- Haloalkane: When hydrogen in an alkane is replaced by a halogen (Cl, Br, I, F).
- Haloarene: When hydrogen in an aromatic ring (such as benzene) is replaced by a halogen.
- Uses in daily life: Thyroxine hormone, anesthesia, solvent, pesticide, etc.
Categories and Nomenclature
- Haloalkane: Alkyl group + halogen (e.g., methyl chloride)
- Haloarene: Aromatic ring + halogen (e.g., chlorobenzene)
- Both IUPAC and common names are explained.
- According to position: mono, di, tri-haloalkane/arene.
- Use of prefixes like iso, neo, secondary, etc.
Classification Based on Carbon Hybridization
- sp3 hybridized carbon: alkyl halide
- sp2 hybridized carbon: vinyl/aryl halide
- Benzyl halide: sp3 carbon attached to benzene ring.
Preparation Methods (Preparation)
- Making haloalkanes from alkenes or alcohols.
- Free radical halogenation, addition reaction, substitution.
- Haloarene: electrophilic substitution, Sandmeyer, Gattermann reaction.
- Specific reactions: Markovnikov rule, Williamson synthesis, Finkelstein, Swarts reaction.
Physical Properties
- Boiling point: higher than hydrocarbons, decreases with branching.
- Density: increases with increasing halogen.
- Solubility: slightly polar, less soluble in water, soluble in organic solvents.
- Color and state: lower members are gases, higher members are liquids/solids.
Major Reactions and Mechanisms
- Free radical halogenation produces a mixture of many isomers.
- Electrophilic substitution produces ortho and para products.
- Markovnikov rule: the negative part attaches to the carbon with fewer hydrogens.
Key Terms & Definitions
- Haloalkane тАФ organic compound with halogen attached to alkane
- Haloarene тАФ compound with halogen attached to aromatic ring
- Markovnikov rule тАФ in electrophilic addition, the negative part attaches to the carbon with fewer hydrogens
- Finkelstein reaction тАФ making iodide from alkyl halide (NaI/acetone)
- Swarts reaction тАФ making fluoro halide (AgF/silver fluoride)
Action Items / Next Steps
- Practice questions on haloalkane/haloarene nomenclature.
- Study chemical properties and reactions in the next video.
- Write mechanisms of important reactions with diagrams.