HALOALKANES Flashcards
How to name haloalkanes
find the longest carbon chain
the name a position of the halogen are the prefix ( 3 - halo - )
if more than one of the same halogen use di, tri, tetra as a prefix
What is a nucleophile and why do they attack haloalkanes
an electron pair donor (CN- NH3 OH- H2O )
as the bond between the carbon and the halogen is polar
the nucleophiles are attracted to the delta positive carbon and will donate their electron pair
How do haloalkanes react with hydroxide ions and what are conditions
Via nucleophilic substitution
warm aqueous NaOH
carried out under reflux
lone pair on OH- ions form a bond with the carbon, so carbon - halogen bond breaks heterolytically
leaves an alcohol
leaves an alcohol
haloalkane reaction with water
nucleophilic substitution
heat with water
leaves an alcohol
Reactivity of haloalkanes
become more reactive with halogens down the group become hydrolysed faster
this is because the bond enthalpy decreases down the group with carbon
how to test reactivity of haloalkanes
add different haloalkanes to different test tubes
add silver nitrate and ethanol to each test tube
yellow precipitate (AgI) will form first
Cream precipitate (AgBr) will form second
white precipitate (AgCl) will form last
What are CFCs and how are they broken down
Chlorofluorocarbons CF2Cl2
C-Cl bonds are broken down by UV light to form radicals as they have a lower bond enthalpy than C-F bonds
How do CFCs destroy ozone and show the mechanisms
CFCs break down to form chlorine radicals by UV radiation
I CCl2F2 + UV –> .CClF2 + Cl.
P Cl. + O3 –> ClO. + O2
ClO. + O3 –> Cl. + 2O2 (as Cl. is
reformed it acts as a catalyst)
T Cl. + Cl. –> Cl2
What is another radicals can destroy ozone
Nitrous oxide can form an NO. radical
General radical mechanism for destruction of ozone
R + O3 –> O2 + RO
RO + O3 –> 2O2 + R
