Ch.15 Haloalkanes

Increases Due to more electrons in the longer chain leading to stronger London forces Which require more energy to overcome

Increases The halogen gets bigger meaning more electrons leading to stronger London forces Which require more energy to overcome

Cannot form H bonds

Carbon, because halogen atoms are more electronegative it makes the C delta +

Heated under reflux (too slow at room temp) with aqueous sodium hydroxide

carbon atom is slightly + attracts species containing lone pairs - nucleophiles nucleophile is attracted to electron poor atoms and donates electron pair forming a covalent bond a nucleophile can replace a halogen

C-F this is because F is same size as C therefore better overlap C-Cl C-Br C-I

Weaker the C-halogen bond is the faster it will break resulting in it being more reactive

aqueous silver nitrate H2O acts as nucleophile use ethanol solvent allowing water and haloalkane to mix OH subs for halogen halide ion react with Ag+ ions forming a silver halide precipitate

halogen replaced by OH in nucleophilic substitution OH- nucleophile lone pair is attracted to and donated to the partially + C C-halogen bond breaks through heterolytic fission forms and alcohol and halide ion

in ozone layer UV splits O2 into 2 O radicals a steady state is then reached O2 + O = O3 then O3 is broken down again the rate of formation is the same as the rate of breakdown human activity in the use of organohalogen has disrupted this equilibrium

UV in the stratosphere provides enough energy for the carbon - halogen bonds to break by homolytic fission forming radicals this is called photodissociation

propagation 1. Cl. + O3 –> ClO2. + O2 2. ClO. + O –> Cl. + O2 O3 + O –> 2O2

NO. radicals form naturally when lightning strikes and as a result of aircraft travel they act as a catalyst in the same way as the Cl. radicals do