Alkyl Halides and Aryl Halides Study Notes

Functional Groups

  • Definition: A functional group is an atom or group of atoms that consistently react in a specific manner within an organic molecule.

  • Key Families and Formulas:     * Ester: functional group −COO−-COO-, general formula R−C−O−RR-C-O-R, molecular formula CnH2nO2C_nH_{2n}O_2.     * Ether: functional group −O−-O-, general formula R−O−RR-O-R.     * Amine: functional group −NH2-NH_2 (Amino).     * Amide: functional group −CO−NH2-CO-NH_2.     * Thiol: functional group −SH-SH, general formula R−S−HR-S-H.

Alkyl and Aryl Halides

  • Alkyl Halide: An organic compound with a halogen atom covalently bonded to an aliphatic carbon atom.

  • Aryl Halide: An organic compound with a halogen bonded to an aromatic group.

  • IUPAC Naming Rules:     * Use a prefix to identify the halogen present.     * Multiple halogens must be listed in alphabetical order.

  • Nomenclature Examples:     * Methyl chloride: CH3−ClCH_3-Cl     * Vinyl chloride: H2C=CHClH_2C=CHCl     * Chlorobenzene

Boiling Point Trends in Alkyl Halides

  • Periodic Table Trend: Boiling points of alkyl halides increase as you move down the halogen column (F→Cl→Br→IF → Cl → Br → I).

  • Mechanism of Increase:     * As the number of electrons increases, they reside farther from the nucleus.     * These electrons shift positions more easily, leading to a higher tendency to form temporary dipoles.     * Intermolecular attraction between dipoles increases the energy required to separate molecules, resulting in higher boiling points.