Final answer:
Halogenation is a reaction where halogens react with alkanes or unsaturated compounds, resulting in the addition of halogen atoms to form haloalkanes or the saturation of double or triple bonds. It often requires specific conditions like ultraviolet light, heat, or catalysts. These reactions open pathways for further transformations in organic synthesis, including substitution mechanisms.
Step-by-step explanation:
Halogenation is a chemical reaction where halogens (chlorine or bromine) react with alkanes or unsaturated compounds like alkenes and alkynes. For alkanes, halogenation occurs under the influence of ultraviolet light or high temperatures, where free radical reactions lead to the formation of haloalkanes. An example is the reaction of chlorine with methane to produce methyl chloride (CH3Cl).
When dealing with alkenes and alkynes, these reactions are typically milder and often spontaneous, adding a halogen atom to each carbon involved in the double or triple bond, which is known as an addition reaction. On the other hand, in hydrogenation, hydrogen gas adds to unsaturated bonds, often requiring a metal catalyst and sometimes high pressure.
The production of alkyl halides via free radical reactions sets the stage for further chemical transformations, such as nucleophilic substitutions where a nucleophile replaces a leaving group, as seen in the conversion of a primary alkyl halide through an SN2 mechanism, often with inversion of stereochemistry.