Alkyl Halides Part 1 PDF

Alkyl Halides Organic chemistry Alkyl Halides Introduction Alkyl halides are organic molecules containing a halogen atom bonded to an sp3 hybridized carbon atom. The halogen atom in halides is often denoted by the symbol; X. Alkyl halides are classified as primary (1°), secondary (2°), or tertiary (...

Alkyl Halides Organic chemistry Alkyl Halides Introduction Alkyl halides are organic molecules containing a halogen atom bonded to an sp3 hybridized carbon atom. The halogen atom in halides is often denoted by the symbol; X. Alkyl halides are classified as primary (1°), secondary (2°), or tertiary (3°), depending on the number of carbons bonded to the carbon with the halogen atom. Alkyl Halides Alkyl Halides Types of Alkyl Halides Vinyl halides have a halogen atom (X) bonded to a C-C double bond. Aryl halides have a halogen atom bonded to a benzene ring. Alkyl Halides Types of Alkyl Halides Allylic halides have X bonded to the carbon atom adjacent to a C-C double bond. Benzylic halides have X bonded to the carbon atom adjacent to a benzene ring. Nomenclature Nomenclature Alkyl Halides Common Names of Alkyl Halides Common names are often used for simple alkyl halides. to assign a common name: 1. Name all the carbon atoms of the molecule as a single alkyl group. 2. Name the halogen bonded to the alkyl group. 3. Combine the names of the alkyl group and halide, separating the words with a space. Alkyl Halides Polarity of Alkyl Halides Alkyl halides are weakly polar molecules. They exhibit dipole-dipole interactions because of their polar C-X bond. Since the rest of the molecule contains only C-C and C-H bonds, they are incapable of intermolecular hydrogen bonding. Alkyl Halides Alkyl Halides Simple Alkyl Halide of Medical Importance Halothane (CF3CHCLBr) is a safe general anesthetic that has now replaced other organic anesthetics such as CHCl3, which causes liver and kidney damage, and CH3CH2OCH2CH3 (diethyl ether), which is very flammable Note: CHCl3 is chloroform Alkyl Halides The Polar Carbon-Halogen Bond The electronegative halogen atom in alkyl halides creates a polar C-X bond, making the carbon atom electron deficient. Electrostatic potential maps of four simple alkyl halides illustrate this point, as shown in figure below. This electron deficient carbon is a key site in the reactivity of alkyl halides. Alkyl Halides Preparing Alkyl Halides from Alkanes: Radical Halogenation Alkane + Cl2 or Br2, heat or light replaces C-H with C-X but gives mixtures 1. Hard to control 2. Via free radical mechanism It is usually not a good idea to plan a synthesis that uses this method—multiple products At the end we will have mixtures of CH3Cl, CH2Cl2, CHCl3, and CCl4 Alkyl Halides Preparing Alkyl Halides from Alkenes Alkyl halide from addition of HCl, HBr, HI to alkenes to give Markovnikov product. Alkyl Halides Preparing Alkyl Halides from Alcohols Reaction of tertiary C-OH with HX is fast and effective Add HCl or HBr gas into ether solution of tertiary alcohol Alkyl Halides Preparing Alkyl Halides from Alcohols Primary and secondary alcohols react very slowly and often rearrange, so alternative methods are used: SOCl2 or PBr3 Alkyl Halides Preparing Alkyl Halides by using Phosphorous Halides Alkyl Halides Preparation of Alkyl Halides from Alcohols and Hydrogen Halides Alkyl Halides Preparation Review Alkyl Halides Reaction Types for Alkyl Halides Alkyl halides undergo substitution reactions with nucleophiles. Alkyl halides undergo elimination reactions with Brønsted-Lowry bases. Alkyl Halides Substitution Reactions Three components are necessary in any substitution reaction.