Reactions of Alkanes Flashcards
Why do the usually unreactive alkanes react with halogen radicals?
Halogen radicals can replace the hydrogen atoms in their structure
What are the steps for the mechanism of the halogenation of alkanes?
1.) Initiation
2.) Propagation
3.)Termination
Which mechanisation step for the halogenation of alkanes happens in two parts?
Propogation
What conditions are needed for initiation to occur?
UV(-b) radiation
What kind of fission occurs when a halogen is exposed to UV radiation?
Homolytic fission
What is the name that is given to the substitution of halogen radicals with hydrogen atoms?
Radical substitution
What is a radical?
The products of homolytic fission
What is homolytic fission?
When atoms from a broken covalent bond receive the same amount of electrons.
What is the word equation of initiation?
Molecule –> Radical + Radical
How are most radicals represented?
With a dot next to their chemical symbol
How are oxygen radicals represented?
O (and no dot)
How does the first propagation step occur?
The halogen radical reacts with the C-H bond in the alkane to form a hydrogen halide and an alkane radical
How does the second propagation step occur?
The alkyl radical reacts with another halogen molecule to form a haloalkane and a halogen radical
What is the general equation for the halogenation of an alkane?
Molecule + Radical –> Molecule + Radical
What is termination?
Two radicals colliding to create a molecule
What is the word equation for termination?
Radical + Radical –> Molecule
What are the limitations for using radical substitution in Organic Synthesis?
-Further substitution of hydrogen atoms in propagation
-Substitution can occur at different points of the carbon chain
