4.2.2 Haloalkanes

Haloalkanes

Haloalkanes

Saturated organic compounds that contain carbon atoms and at least one halogen atom

Are haloalkanes soluble in water?

Insoluble in water- C-H bonds are non-polar, not compensated for enough by C-X bond polarity

Do haloalkanes have a polar bond?

Yes, a halogen has a higher electronegativity than C

What type of intermolecular forces do they have?

Permanent dipole-dipole forces
C-X bond polarity creates permanent dipoles

When do their boiling points increase?

Increase carbon chain length
Halogen further down group 7

Primary halogen

Halogen atom is present at the end of the chain

Conditions for halogenation

Halogen
UV light

How are haloalkanes formed from alkanes?

Radical substitution

What are the three stages of radical substitution?

Initiation- breaking halogen bond to form radicals
Propagation- chain part of the reaction where products are formed but free radical remains
Termination- free radicals removed, stable products formed

CFCs

Chlorine-fluoro-carbons
Haloalkanes containing C, F and Cl only

What is the problem with CFCs?

Catalyse the breakdown of ozone in the atmosphere via radical substitution

What is the main function of the ozone layer?

Provides protection from harmful UV radiation

What can decompose ozone?

CFCs
Nitrogen monoxide (NO)