Full Chapter Notes
Short Question
MCQ’s with Exercise
Class 12th Chemistry Chapter – “Alkyl Halides” focuses on the properties, structures, and reactions of alkyl halides, which are organic compounds containing carbon and halogen atoms. Here’s a brief overview:
Definition
- Alkyl Halides: These are compounds derived from alkanes by replacing one or more hydrogen atoms with halogen atoms (F, Cl, Br, or I). They can be classified as primary, secondary, or tertiary based on the carbon atom bonded to the halogen.
Structure
- Alkyl halides can be represented by the general formula CₙH₂ₙ₊₁X, where X represents the halogen. The halogen atom is bonded to a saturated carbon atom, influencing the compound’s reactivity and physical properties.
Properties
- Physical Properties:
- Alkyl halides are typically colorless liquids or solids with distinctive odors.
- They have higher boiling and melting points than their parent alkanes due to the presence of polar carbon-halogen bonds.
- Solubility varies: lower alkyl halides are generally soluble in organic solvents but less soluble in water.
- Chemical Properties:
- Alkyl halides undergo nucleophilic substitution reactions, where the halogen atom is replaced by a nucleophile (e.g., OH⁻, NH₃).
- They can also participate in elimination reactions, leading to the formation of alkenes.
Reactions
- Nucleophilic Substitution: The most significant reactions for alkyl halides. Two main mechanisms are:
- S_N1 Mechanism: Involves the formation of a carbocation intermediate and is favored by tertiary alkyl halides.
- S_N2 Mechanism: Involves a direct attack by the nucleophile, resulting in the inversion of configuration and is favored by primary alkyl halides.
Applications
- Alkyl halides are used in various applications, including:
- Solvents: Many alkyl halides serve as solvents in organic reactions.
- Reagents: They are important intermediates in the synthesis of pharmaceuticals, agrochemicals, and other organic compounds.
This chapter provides insights into the structure and reactivity of alkyl halides, emphasizing their significance in organic chemistry and industrial applications.