1. substrate:
for sn2 mechanism, the order of substrates are 10
> 20> 30
for sn1 mechanism the reactivity order of substrate is
30 > 20 > 10.
2. nature of leaving group:
conjugate base of weak acid is the good leaving group in sn2
& sn2
3. nature of nucleophile:
strong nucleophiles favors sn2 mechanism
weak / moderate nucleophiles favours sn1 mechanism.
4. solvent
polar protic solvents favours sn1 mechanism
polar aprotic solvents favours sn2 mechanism.
