Halogenation of Unsaturated Hydrocarbons Using Hydrogen Halides in a Hydrohalogenation Reaction Chemistry Tutorial
- A hydrocarbon is a molecule containing only carbon and hydrogen.
- Unsaturated hydrocarbon molecules contain either a double bond (C=C) or a triple bond (C≡C)
- Alkenes are unsaturated hydrocarbons with a double bond (C=C).
- Alkynes are unsaturated hydrocarbons with a tripe bond (C≡C)
- The active site in alkenes is the double bond.
The active site in alkynes is the triple bond.
- The elements of Group 17 are known as halogens.
Fluorine (F), chlorine (Cl), bromine (Br) and iodine (I) are halogens.
A halogen atom is usualy given the general symbol X
- Hydrogen halides are covalent molecules with the general formula HX
HBr is hydrogen bromide, HI is hydrogen iodide
- Unsaturated hydrocarbons (alkenes and alkynes) react with hydrogen halides (HX) in addition reactions producing halogenated compounds.
alkene + hydrogen halide → haloalkane H
R - C = C - R' + H-X → H
R - C - C - R' |
- If the alkene or alkyne molecule is symmetrical, R is the same as R', then only one product is formed.
- If the alkene or alkyne molecule is unsymmetrical, R is NOT the same as R', then more than one product will be produced.
- Markovnikov's Rule is applied in order to determine which product is produced with the the greater yield, the major product.
- Markovnikov's Rule:
In additions of HX to unsymmetrical alkenes, the H+ of HX goes to the double-bonded carbon that already has the greatest number of hydrogens