Topic 13: Haloalkanes Flashcards
Haloalkane
Halogen replacing H on an alkane
Free-radical substitution steps
Initiation
Propagation
Termination
Initiation
X2 —> UV light 2X○
Cl2 —> 2Cl○
Propagation
CH4 + Cl○ —> HCl(g) (misty fumes) + ○CH3 DRAW ON LEFT HAND SIDE
○CH3 + Cl2 —> CH3Cl + Cl○
Termination
Cl○ + Cl○ —> Cl2
Cl○ + ○CH3 —> CH3Cl
○CH3 + ○CH3 —> C2H6
There are more, add them i cbb atm
CFCs
Chlorofluorocarbons eg
CHClF2 —> UV light Cl○ + CHF○
Cl○ + O3 —> ClO○ + O2
ClO○ + O3 —> 2O2 + Cl○
Ozone forms layer
Homolytic fission
The process of breaking a covalent within a molecule leading to the formation of radicals
CFCs why used
Good solvents
Ozone
Protects from uv light
Nucleophilic substitution
An electron-rich nucleophile attacks a positive charge or partial positive charge to replace an atom/ group of atoms (usually attacks a haloalkane)
Nucleophile
Donates a pair of electrons to form a bond
Nucleophilic substitution mechanism
Arrow from lone pair to carbon
Arrow from bond to Bromine
Partial charges
Lone pair
Nucleophiles examples
:OH- , :-CN ALWAYS ON THE CARBON, :NH3
Created from cyanide nucleophile attacking haloalkane
Added carbon to chain
Nitrile group
e.g. propanenitrile
Ammonia nucleophile attacking haloalkane and product
Another ammonia attacks
Arrow from bond to N
Arrow from ammonia nucleophile to hydrogen
Primary Amine
Conditions for elimination
Heat under reflux
Use ethanol as solvent NO WATER
Elimination mechanism
Arrow from nucleophile to hydrogen
Arrow from that c-h bond to c-c bond
Arrow from C-br bond to BR
Cascade lighting bolt shape
Nucleophile acts as what in elimination reation
Base
Elimination with hydroxide nucleophile creates
Alkene with double bond and water
