ORGANIC CHEMISTRY
Haloalkanes:
- Overview:
- Haloalkanes, also termed alkyl halides, are organic compounds characterized by the presence of halogen atoms (fluorine, chlorine, bromine, or iodine) bonded to alkyl groups.
- Their general formula is R-X, where R denotes an alkyl group and X signifies a halogen atom.
- Classification:
- Haloalkanes are categorized based on the number of carbon atoms to which the halogen atom is bonded:
- Properties:
- Haloalkanes exhibit polarity due to the difference in electronegativity between carbon and halogen, resulting in them being polar molecules.
- Their boiling points tend to be higher compared to those of alkanes due to the presence of polar bonds.
- Solubility diminishes with increasing molecular weight due to reduced polarity.
- Chemical Reactions:
- Substitution Reactions: Halogen atoms in haloalkanes can be substituted by other nucleophiles.
- Elimination Reactions: Under certain conditions, haloalkanes undergo elimination reactions to yield alkenes.
- Reduction Reactions: Haloalkanes can be reduced to alkanes using reducing agents like lithium aluminum hydride (LiAlH4).
- Nucleophilic Substitution Reactions: Haloalkanes react with nucleophiles to undergo substitution reactions where the halogen atom is replaced.
- Uses:
- Haloalkanes are utilized as solvents, refrigerants, pesticides, and in pharmaceutical synthesis.
- Some serve as anesthetics and are involved in plastic production.
Haloarenes:
- Overview:
- Haloarenes are aromatic compounds featuring halogen atoms directly bonded to the aromatic ring.
- Their general formula is Ar-X, where Ar represents an aromatic ring and X represents a halogen atom.
- Properties:
- Haloarenes exhibit relatively lower reactivity compared to haloalkanes due to resonance stabilization of the aromatic ring.
- They possess lower boiling points than haloalkanes of similar molecular weight.
- Haloarenes are less soluble in water owing to the non-polar nature of the aromatic ring.
- Chemical Reactions:
- Electrophilic Substitution: Haloarenes undergo electrophilic aromatic substitution reactions where a halogen atom is replaced by an electrophile.
- Sandmeyer Reaction: Involves converting aryl diazonium salts into haloarenes.
- Wurtz-Fittig Reaction: Haloarenes can be coupled with alkyl halides in the presence of sodium metal to form biaryl compounds.
- Uses:
- Haloarenes find applications in organic synthesis, pharmaceuticals, agrochemicals, and dyes.
- Some are utilized as intermediates in plastic and fragrance production.