Haloalkanes Flashcards
What reaction do they undergo?
Nucleophilic substitution
How are they polar?
Halogens are more electronegative than carbons, so the slightly positive carbon attracts species with lone pairs.
What are examples of nucleophiles?
OH-, H2O, NH3
How are haloalkanes hydrolysed?
Halogen is replaced by an OH group to form an alcohol and halide ion. Under reflux with NaOH to increase yield (stops loss of volatile products).
How is hydrolysis rate measured?
Using silver nitrate to form a precipitate. Haloalkanes are insoluble in water so an ethanol solvent in used.
The more stable the carbocation, the faster the rate of hydrolysis. eg. primary is less stable
What are uses of organohalogen in the environment?
Dry cleaning solvents
Making polymers
Refrigerants
Pesticides
Are organohalogens reactive?
No, they are very inert so are safe to use.
What is the function of the ozone layer?
It absorbs most of the damaging UV radiation - sunburn.
O3 is present. If too much is depleted, more reaches the earth.
What are the dangers of ozone?
Increased risk of genetic damage and skin cancer.
Why are CFCs bad?
They disrupted the equilibrium, as when they reach the stratosphere they break down to form a Cl radical.
What does the Cl radical do?
It is very reactive, so catalyses the breakdown of ozone layer by photodissociation of C-Cl bond.
What is the overall equation for the breakdown of ozone?
O3 + O –> 2O2
How is NO’ formed?
Lightning and plane exhaust. It does the same as Cl’ by breaking down ozone (same equation overall).
