4.2.2- Haloalkanes Flashcards
What are haloalkanes?
Saturated organic compounds that contain carbon atoms and at least one halogen atoms
Are haloalkanes soluble in water?
Insoluble as C-H bonds are non-polar, not compensated for enough by C-X bond polarity
Do haloalkanes have a polar bond? Why?
Yes polar, as halogen has a higher electronegativity than C
What type of intermolecular forces do they have? Why?
- Permanent dipole-dipole and London forces of attraction
- C-X bond polarity creates permanent dipole
When would they have higher boiling points?
Increase carbon chain length
Halogen further down group 7
How would the mass of a haloalkane compare with the mass of an alkane of the same chain length?
Greater as mass of halogen > mass of H
What is the most important factor in determining halogen reactivity?
The strength of carbon halogen bond
What would bond polarity suggests the order of reactivity would be?
C-F would be most reactive as most polar bond
What would bond enthalpies suggests the order of reactivity would be?
C-I would be most reactive as lowest bond enthalpy
What is a primary halogen?
The halogen atom is present at the end of the chain
Define nucleophile
Electron pair donor
Give 3 examples of nucleophiles
:OH-
:CN-
:NH3
What is nucleophilic substitution?
A reaction where a nucleophile donates a lone pair of electrons to slightly positive C atom, electronegative atom leaves molecule (replaced by nucleophiles)
What is hydrolysis?
A reaction where water is a reactant
What reactant often produces hydroxide ions for hydrolysis?
Water
What fission does water undergo to produces OH-?
Heterolytic fission
What are CFCs?
Chloro-fluoro-carbons- haloalkanes containing C, F and Cl only (no H)
What is problem with CFCs?
Although, unreactive under normal conditions, they catalyse the breakdown of ozone in the atmosphere via free radical sunstitution
What is main function of ozone layer?
Provides protection from harmful UV radiation
Does ozone play a protection role in all layers of the atmosphere?
No, in the troposhere it contributes to photochemical smog
How do CFCs break the ozone layer down?
Free radical substitution
