Tiêu đề 28.-Haloalkane-_-Haloarene-Notes.pdf ✅

1. Haloalkanes and Haloarenes Haloalkanes Haloalkanes are the halogen deivatives of hydrocarbons. Classification of Haloalkanes Monohalides (R–X): Monohalides are monohalogen derivatives of alkanes which have a general formula CnH2n+1X and are known as alkyl halides. R–X may be of three types: 1. Primary R–CH2X 2. Secondary R2CHX 3. Tertiary R3CX Dihalides (CnH2nX2): Dihalides are the di-halogen derivatives of alkanes and are of geminal and vicinal types. Example (a) CH3CHBr2 (Ethylidine dibromide), (b) BrCH2CH2Br (Ethylene dibromide) Trihalides (CnH2n–1X3) or haloforms: Trihalides are tri-halogen derivatives of alkanes and are represented by a general formula CHX3 (haloforms). Tetrahalides: Tetrahalides are tetra-halogen derivatives of alkanes and arerepresented by a general formula CX4 or CX2 Y2. Aromatic Halogen Compounds When halogen atom is attached to aromatic hydrocarbons directly to the ring , the substance is known aryl halides. Their general formula is Ar—X. Haloalkanes and Haloarenes Concept Ladder In haloalkanes, the halogen atom is attached to the sp3- hybridised carbon atom of an alkyl group whereas in haloarenes, the halogen atom is attached to sp2 - hybridized carbon atom of an aryl group. Definitions The monohalogen derivatives of alkanes are called alkyl halides or monohaloalkanes or simply haloalkanes. Concept Ladder Haloalkynes or Alkynyl halides are the halogen derivatives of alkynes. The monohalogen derivatives of alkynes have the general formula CnH2n-3X where X=F, Cl Br or I and n = 2, 3, 4....., etc.