DJA 3). Mecanisms simple editor Flashcards
free radical
A chemical species with an unpaired electron - usually highly reactive`
how many stages to free radical substitution
3
what are the stages of free radical substitution (short)
initiationpropagationtermination
initiation
free radicals are producedCl2 ——-> •Cl +•Cl
Propagation
‘Recycling the free radical’a). Cl• + CH3CH3——–> CH3•CH2 + HCl (dot usually above C)b). CH3•CH2 + Cl2—–> CH3CH2Cl + Cl•free radical used and then reformed
Termination
Two free radicals collidingCH3•CH2+ Cl• ——->CH3CH2ClCl• + Cl• ——–> NO JUST REFORMS WITH UV LIGHTCH3•CH2 +CH3•CH2——-> CH3CH2CH2CH3
Further substitution
If Cl2is in excess then the product will react with more and more Cl2.Then that new product wil react with more Cl2and so on….
what is a nucleophile
a species that contains a lone pair of electrons
3 examples of nucleophiles correctly written
negative (xx) OH(xx) NH3negative (xx) CN
What happens during nucleophlic substitution
The nucleophile will swap places with another nucleophile on a molecule
Least reactive haloalkane
fluoro….
most freactive haloalkane
iodo…..
strongest haloalkane bond
fluoro….
weakest haloalkane bond
iodo…
explanation for strongest bond
shortest bond, electron pair in the bond is closest to the nucleus of F and there is little shielding therefore it is more strongly attracted