Studied by 1 personBond fission is the breaking of a covalent bond.
What is bond fission?
Homolytic fission
Heterolytic fission
What are the two ways a bond can break?
The uneven breaking of bonds.
One of the bonded atom receives both electrons form the bonded pair.
Two different substances are formed - a positively charged cation and and a negatively charged anion.
What is heterolytic fission?
The even breaking of bond.
Each atom receives one electron from the bonded pair.
Two radicals are formed (radicals are particles that have an unpaired electron.)
Because of the unpaired electron, radicals are very reactive.
What is homolytic fission?
Free-radical substitution with UV light
What reaction forms haloalkanes from alkanes?
Halogens
What do alkanes react with to form haloalkanes?
Initiation
Propagation
Termination
What are the three steps to a free-radical substitution mechanism?
Sunlight provides enough energy to break the bond in the halogen.
Homolytic fission takes place and the atom becomes a highly reactive free radical because of its unpaired electron.
What happens in the initiation stage of the reaction?
Free radicals are used up and created in a chain reaction.
What happens in the propagation stage of the reaction?
Free radicals join together to make a stable molecule.
What happens in the termination stage of the reaction?
You don’t only get the product you are trying to make you get a mixture of products.
It can take place at any point along the carbon chain so a mixture of isomers can be formed.
What are two problems with free-radical substitution?
Note
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