Haloalkanes

Cn H2n+1 X or R-X

The carbon that the halogen is bonded to is itself only bonded to one other carbon

The carbon that the halogen is bonded to is itself bonded to two other carbons

The carbon that the halogen is bonded to is itself bonded to three other carbons

Because the C-X bond is not polar enough.

Free radical substitution

Initiation, propagation, termination.

Initiation- UV light breaks the bond in the halogen molecule creating two halogen atoms each with a lone electron (free radical). This is homolytic fission. Propagation- Halogen radical reacts with hydrogen atom from an alkane making a methyl free radical and hydrogen halide. The methyl free radical reacts with a halogen molecule creating a haloalkane and another halogen free radical. Termination. Free radicals are removed by reacting with other free radicals.

In the stratosphere and troposphere upper atmosphere

It blocks most of the UV radiation from the sun which is harmful to life.

CFCs from refrigerators end up in the stratosphere. The UV radiation is absorbed by them and it breaks the C-Cl bond. One of the shared electrons goes to the released chlorine atom forming a chlorine free radical.

CCl3F -> *CCl2F + Cl *Cl + O3 -> *ClO + O2 *ClO + O3 -> *Cl + 2O2 2O3 -> 3O2 Equation 3 shows how chlorine free radicals can be regenerated so continue to catalyse the decomposition of the ozone layer.

Alkanes and hydrofluorocarbons (chlorine free)

To find an alternative route or lower activation energy.

A negative ion or molecule that is able to donate a pair of electrons (its lone pair) to an electron deficient area of another reactant.

Arrow from lone pair on oxygen atom to the delta positive carbon atom. Arrow from C-X bond to the delta negative halogen. OH is where X was and X is the leaving group with a lone pair and full negative charge. 50:50 ethanol:water. Can happen at room temperature but slowly. Forms an alcohol.

Arrow from lone pair on the carbon atom (cyanide) to the delta positive carbon atom (haloalkane). Arrow from C-X bond to the delta negative halogen. CN is where X was and X is the leaving group with a lone pair and full negative charge. The solution is aqueous and alcoholic and warmed. The product is a nitrile with one more carbon than the original haloalkane.

Arrow from lone pair of nitrogen atom to the delta positive carbon. Arrow from C-X bond to the delta negative halogen. NH3 is where X was and X is leaving group with a lone pair and full negative charge. Arrow from N+-H bond to N. Arrow from lone pair of nitrogen atom from other ammonia molecule to same H. Forms amine (with lone pair on N) and ammonium (+ on N). Needs excess concentrated ammonia solution in ethanol carried out under pressure.

Splitting molecules using water

Add 1cm^3 of each to separate test tubes. Pipette 1cm^3 of silver nitrate solution into one and time how long it takes until a precipitate is first seen. Do the same with the other test tubes under the same temperature. Shorter time means a higher rate of reaction,

Arrow from lone pair of oxygen atom to hydrogen bonded to carbon next to the carbon the halogen is bonded to. Arrow from C-H bond (same H) to C-C bond. Arrow from C-X bond to halogen. X is leaving group with a lone pair and full negative charge. Forms an alkene and water. Needs ethanol as solvent with no water and is heated.

Primary - substitution Secondary - both Tertiary- elimination