Haloalkanes Flashcards
What are the three steps in free radical substitution?
- Initiation
- Propagation
- Termination
What is the bond polarity of haloalkanes like?
They are polar due to the halogen being more electronegative than C
What is the solubilty of haloalkanes?
The polar bonds are not polar enough to make haloalkanes soluble in water
What are nucleophiles?
Electon pair donators ( either a negatively charged ion or has atoms with a slight negative charge.
What can nucleophilic substitution also be called?
Hydrolysis
What does an elimination reaction form?
An alkene
What do we call a nucleophile in a elimination reaction?
base
Is there any water present during elimination reactions?
No
Do elimination reactions occur at low or high temperatures?
High
Does elimination or substitution reactions produce a primary haloalkane?
Substitution
Does elimination or substitution reactions produce tertiary haloalkanes?
Elimination
What reaction occurs for the formation of secondary haloalkanes?
Both, either substitution or elimination
Draw a primary haloalkane.
Br-C-C
Draw a secondary haloalkanes.
C-C-C
l
Br
Draw a tertiary haloalkane.
C
l
C-C-C
l
Br
What is one of the causes of the depletion of the ozone layer?
CFCs (Chlorofluorocarbon)
Why is the Ozone layer important?
- Protects the earth from harmful exposure to UV rays
- Plankton in the sea need protection
- Too much UV radiation causes skin cancer
What does a CFC contain?
Chlorine , Fluorine and Carbon
What are some uses of short chain CFCs?
- Refrigerants
- Aerosol propellants
What are some uses of long-chain CFCs?
- Dry cleaning
- De-greasing solvents
How do CFCs remove ozone?
- The stable CFCs reach the stratosphere where they react with UV light and the C-Cl bond breaks homolytically which produces very reactive chlorine free radicals.
CCl3F —> ∙CCl2F + ∙Cl - The chlorine free radicals react with Ozone molecules and theyv remove them from the Ozone cycle.
∙Cl + O3 —> ∙ClO + O2 - The resulting free radicas also attack Ozone , regenerating ∙Cl
∙ClO + O3 —> ∙Cl + 2O2
The chlorine free radical isn’t destroyed, it acts as a catalyst in the breakdown of Ozone to Oxygen
What is the overall equation for the depletion of the Ozone layer by CFCs?
2O3 —> 3O2
What are the reagents, conditions and products during the Nucleophilic substitution of a haloalkane with a hydroxide?
Reagents: Haloalkanes and NaOH or KOH (aq)
Conditions: Under reflux and ethanol is used as a solvent but WATER is also present
Products: Alcohol and a halide ion
What are the reagents, conditions and products during the Nucleophilic substitution of Haloalkanes with CN (nitrile)
Reagents: Haloalkanes and NaCN or KCN
Conditions: Under reflux and ethanol is used as a solvent but WATER is also present
Products: Nitrile and Halide ion
